Search Results: "eric"

9 January 2024

Louis-Philippe V ronneau: 2023 A Musical Retrospective

I ended 2022 with a musical retrospective and very much enjoyed writing that blog post. As such, I have decided to do the same for 2023! From now on, this will probably be an annual thing :) Albums In 2023, I added 73 new albums to my collection nearly 2 albums every three weeks! I listed them below in the order in which I acquired them. I purchased most of these albums when I could and borrowed the rest at libraries. If you want to browse though, I added links to the album covers pointing either to websites where you can buy them or to Discogs when digital copies weren't available. Once again this year, it seems that Punk (mostly O !) and Metal dominate my list, mostly fueled by Angry Metal Guy and the amazing Montr al Skinhead/Punk concert scene. Concerts A trend I started in 2022 was to go to as many concerts of artists I like as possible. I'm happy to report I went to around 80% more concerts in 2023 than in 2022! Looking back at my list, April was quite a busy month... Here are the concerts I went to in 2023: Although metalfinder continues to work as intended, I'm very glad to have discovered the Montr al underground scene has departed from Facebook/Instagram and adopted en masse Gancio, a FOSS community agenda that supports ActivityPub. Our local instance, askapunk.net is pretty much all I could ask for :) That's it for 2023!

30 December 2023

Russ Allbery: Review: The Hound of Justice

Review: The Hound of Justice, by Claire O'Dell
Series: Janet Watson Chronicles #2
Publisher: Harper Voyager
Copyright: July 2019
ISBN: 0-06-269938-5
Format: Kindle
Pages: 325
The Hound of Justice is a near-future thriller novel with Sherlock Holmes references. It is a direct sequel to A Study in Honor. This series is best read in order. Janet Watson is in a much better place than she was in the first book. She has proper physical therapy, a new arm, and a surgeon's job waiting for her as soon as she can master its features. A chance meeting due to an Inauguration Day terrorist attack may even develop into something more. She just needs to get back into the operating room and then she'll feel like her life is back on track. Sara Holmes, on the other hand, is restless, bored, and manic, rudely intruding on Watson's date. Then she disappears, upending Watson's living arrangements. She's on the trail of something. When mysterious destructible notes start appearing in Watson's books, it's clear that she wants help. The structure of this book didn't really work for me. The first third or so is a slice-of-life account of Watson's attempt to resume her career as a surgeon against a backdrop of ongoing depressing politics. This part sounds like the least interesting, but I was thoroughly engrossed. Watson is easy to care about, hospital politics are strangely interesting, and while the romance never quite clicked for me, it had potential. I was hoping for another book like A Study in Honor, where Watson's life and Holmes's investigations entwine and run in parallel. That was not to be. The middle third of the book pulls Watson away to Georgia and a complicated mix of family obligations and spy-novel machinations. If this had involved Sara's fae strangeness, verbal sparring, and odd tokens of appreciation, maybe it would have worked, but Sara Holmes is entirely off-camera. Watson is instead dealing with a minor supporting character from the first book, who drags her through disguises, vehicle changes, and border stops in a way that felt excessive and weirdly out of place. (Other reviews say that this character is the Mycroft Holmes equivalent; the first initial of Micha's name fits, but nothing else does so far as I can tell.) Then the last third of the novel turns into a heist. I like a heist novel as much as the next person, but a good heist story needs a team with chemistry and interplay, and I didn't know any of these people. There was way too little Sara Holmes, too much of Watson being out of her element in a rather generic way, and too many steps that Watson is led through without giving the reader a chance to enjoy the competence of the team. It felt jarring and disconnected, like Watson got pulled out of one story and dropped into an entirely different story without a proper groundwork. The Hound of Justice still has its moments. Watson is a great character and I'm still fully invested in her life. She was pulled into this mission because she's the person Holmes knows with the appropriate skills, and when she finally gets a chance to put those skills to use, it's quite satisfying. But, alas, the magic of A Study in Honor simply isn't here, in part because Sara Holmes is missing for most of the book and her replacements and stand-ins are nowhere near as intriguing. The villain's plan seems wildly impractical and highly likely to be detected, and although I can come up with some explanations to salvage it, those don't appear in the book. And, as in the first book, the villain seems very one-dimensional and simplistic. This is certainly not a villain worthy of Holmes. Fittingly, given the political movements O'Dell is commenting on, a lot of this book is about racial politics. O'Dell contrasts the microaggressions and more subtle dangers for Watson as a black woman in Washington, D.C., with the more explicit and active racism of the other places to which she travels over the course of the story. She's trying very hard to give the reader a feeling for what it's like to be black in the United States. I don't have any specific complaints about this, and I'm glad she's attempting it, but I came away from this book with a nagging feeling that Watson's reactions were a tiny bit off. It felt like a white person writing about racism rather than a black person writing about racism: nothing is entirely incorrect, but the emotional beats aren't quite where black authors would put them. I could be completely wrong about this, and am certainly much less qualified to comment than O'Dell is, but there were enough places that landed slightly wrong that I wanted to note it. I would still recommend A Study in Honor, but I'm not sure I can recommend this book. This is one of those series where the things that I enjoyed the most about the first book weren't what the author wanted to focus on in subsequent books. I would read more about the day-to-day of Watson's life, and I would certainly read more of Holmes and Watson sparring and circling and trying to understand each other. I'm less interested in somewhat generic thrillers with implausible plots and Sherlock Holmes references. At the moment, this is academic, since The Hound of Justice is the last book of the series so far. Rating: 6 out of 10

27 December 2023

Russ Allbery: Review: A Study in Scarlet

Review: A Study in Scarlet, by Arthur Conan Doyle
Series: Sherlock Holmes #1
Publisher: AmazonClassics
Copyright: 1887
Printing: February 2018
ISBN: 1-5039-5525-7
Format: Kindle
Pages: 159
A Study in Scarlet is the short mystery novel (probably a novella, although I didn't count words) that introduced the world to Sherlock Holmes. I'm going to invoke the 100-year-rule and discuss the plot of this book rather freely on the grounds that even someone who (like me prior to a few days ago) has not yet read it is probably not that invested in avoiding all spoilers. If you do want to remain entirely unspoiled, exercise caution before reading on. I had somehow managed to avoid ever reading anything by Arthur Conan Doyle, not even a short story. I therefore couldn't be sure that some of the assertions I was making in my review of A Study in Honor were correct. Since A Study in Scarlet would be quick to read, I decided on a whim to do a bit of research and grab a free copy of the first Holmes novel. Holmes is such a part of English-speaking culture that I thought I had a pretty good idea of what to expect. This was largely true, but cultural osmosis had somehow not prepared me for the surprise Mormons. A Study in Scarlet establishes the basic parameters of a Holmes story: Dr. James Watson as narrator, the apartment he shares with Holmes at 221B Baker Street, the Baker Street Irregulars, Holmes's competition with police detectives, and his penchant for making leaps of logical deduction from subtle clues. The story opens with Watson meeting Holmes, agreeing to split the rent of a flat, and being baffled by the apparent randomness of Holmes's fields of study before Holmes reveals he's a consulting detective. The first case is a murder: a man is found dead in an abandoned house, without a mark on him although there are blood splatters on the walls and the word "RACHE" written in blood. Since my only prior exposure to Holmes was from cultural references and a few TV adaptations, there were a few things that surprised me. One is that Holmes is voluble and animated rather than aloof. Doyle is clearly going for passionate eccentric rather than calculating mastermind. Another is that he is intentionally and unabashedly ignorant on any topic not related to solving mysteries.
My surprise reached a climax, however, when I found incidentally that he was ignorant of the Copernican Theory and of the composition of the Solar System. That any civilized human being in this nineteenth century should not be aware that the earth travelled round the sun appeared to be to me such an extraordinary fact that I could hardly realize it. "You appear to be astonished," he said, smiling at my expression of surprise. "Now that I do know it I shall do my best to forget it." "To forget it!" "You see," he explained, "I consider that a man's brain originally is like a little empty attic, and you have to stock it with such furniture as you chose. A fool takes in all the lumber of every sort that he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things so that he has a difficulty in laying his hands upon it. Now the skilful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones."
This is directly contrary to my expectation that the best way to make leaps of deduction is to know something about a huge range of topics so that one can draw unexpected connections, particularly given the puzzle-box construction and odd details so beloved in classic mysteries. I'm now curious if Doyle stuck with this conception, and if there were any later mysteries that involved astronomy. Speaking of classic mysteries, A Study in Scarlet isn't quite one, although one can see the shape of the genre to come. Doyle does not "play fair" by the rules that have not yet been invented. Holmes at most points knows considerably more than the reader, including bits of evidence that are not described until Holmes describes them and research that Holmes does off-camera and only reveals when he wants to be dramatic. This is not the sort of story where the reader is encouraged to try to figure out the mystery before the detective. Rather, what Doyle seems to be aiming for, and what Watson attempts (unsuccessfully) as the reader surrogate, is slightly different: once Holmes makes one of his grand assertions, the reader is encouraged to guess what Holmes might have done to arrive at that conclusion. Doyle seems to want the reader to guess technique rather than outcome, while providing only vague clues in general descriptions of Holmes's behavior at a crime scene. The structure of this story is quite odd. The first part is roughly what you would expect: first-person narration from Watson, supposedly taken from his journals but not at all in the style of a journal and explicitly written for an audience. Part one concludes with Holmes capturing and dramatically announcing the name of the killer, who the reader has never heard of before. Part two then opens with... a western?
In the central portion of the great North American Continent there lies an arid and repulsive desert, which for many a long year served as a barrier against the advance of civilization. From the Sierra Nevada to Nebraska, and from the Yellowstone River in the north to the Colorado upon the south, is a region of desolation and silence. Nor is Nature always in one mood throughout the grim district. It comprises snow-capped and lofty mountains, and dark and gloomy valleys. There are swift-flowing rivers which dash through jagged ca ons; and there are enormous plains, which in winter are white with snow, and in summer are grey with the saline alkali dust. They all preserve, however, the common characteristics of barrenness, inhospitality, and misery.
First, I have issues with the geography. That region contains some of the most beautiful areas on earth, and while a lot of that region is arid, describing it primarily as a repulsive desert is a bit much. Doyle's boundaries and distances are also confusing: the Yellowstone is a northeast-flowing river with its source in Wyoming, so the area between it and the Colorado does not extend to the Sierra Nevadas (or even to Utah), and it's not entirely clear to me that he realizes Nevada exists. This is probably what it's like for people who live anywhere else in the world when US authors write about their country. But second, there's no Holmes, no Watson, and not even the pretense of a transition from the detective novel that we were just reading. Doyle just launches into a random western with an omniscient narrator. It features a lean, grizzled man and an adorable child that he adopts and raises into a beautiful free spirit, who then falls in love with a wild gold-rush adventurer. This was written about 15 years before the first critically recognized western novel, so I can't blame Doyle for all the cliches here, but to a modern reader all of these characters are straight from central casting. Well, except for the villains, who are the Mormons. By that, I don't mean that the villains are Mormon. I mean Brigham Young is the on-page villain, plotting against the hero to force his adopted daughter into a Mormon harem (to use the word that Doyle uses repeatedly) and ruling Salt Lake City with an iron hand, border guards with passwords (?!), and secret police. This part of the book was wild. I was laughing out-loud at the sheer malevolent absurdity of the thirty-day countdown to marriage, which I doubt was the intended effect. We do eventually learn that this is the backstory of the murder, but we don't return to Watson and Holmes for multiple chapters. Which leads me to the other thing that surprised me: Doyle lays out this backstory, but then never has his characters comment directly on the morality of it, only the spectacle. Holmes cares only for the intellectual challenge (and for who gets credit), and Doyle sets things up so that the reader need not concern themselves with aftermath, punishment, or anything of that sort. I probably shouldn't have been surprised this does fit with the Holmes stereotype but I'm used to modern fiction where there is usually at least some effort to pass judgment on the events of the story. Doyle draws very clear villains, but is utterly silent on whether the murder is justified. Given its status in the history of literature, I'm not sorry to have read this book, but I didn't particularly enjoy it. It is very much of its time: everyone's moral character is linked directly to their physical appearance, and Doyle uses the occasional racial stereotype without a second thought. Prevailing writing styles have changed, so the prose feels long-winded and breathless. The rivalry between Holmes and the police detectives is tedious and annoying. I also find it hard to read novels from before the general absorption of techniques of emotional realism and interiority into all genres. The characters in A Study in Scarlet felt more like cartoon characters than fully-realized human beings. I have no strong opinion about the objective merits of this book in the context of its time other than to note that the sudden inserted western felt very weird. My understanding is that this is not considered one of the better Holmes stories, and Holmes gets some deeper characterization later on. Maybe I'll try another of Doyle's works someday, but for now my curiosity has been sated. Followed by The Sign of the Four. Rating: 4 out of 10

21 December 2023

Russ Allbery: Review: The Box

Review: The Box, by Marc Levinson
Publisher: Princeton University Press
Copyright: 2006, 2008
Printing: 2008
ISBN: 0-691-13640-8
Format: Trade paperback
Pages: 278
The shipping container as we know it is only about 65 years old. Shipping things in containers is obviously much older; we've been doing that for longer than we've had ships. But the standardized metal box, set on a rail car or loaded with hundreds of its indistinguishable siblings into an enormous, specially-designed cargo ship, became economically significant only recently. Today it is one of the oft-overlooked foundations of global supply chains. The startlingly low cost of container shipping is part of why so much of what US consumers buy comes from Asia, and why most complex machinery is assembled in multiple countries from parts gathered from a dizzying variety of sources. Marc Levinson's The Box is a history of container shipping, from its (arguable) beginnings in the trailer bodies loaded on Pan-Atlantic Steamship Corporation's Ideal-X in 1956 to just-in-time international supply chains in the 2000s. It's a popular history that falls on the academic side, with a full index and 60 pages of citations and other notes. (Per my normal convention, those pages aren't included in the sidebar page count.) The Box is organized mostly chronologically, but Levinson takes extended detours into labor relations and container standardization at the appropriate points in the timeline. The book is very US-centric. Asian, European, and Australian shipping is discussed mostly in relation to trade with the US, and Africa is barely mentioned. I don't have the background to know whether this is historically correct for container shipping or is an artifact of Levinson's focus. Many single-item popular histories focus on something that involves obvious technological innovation (paint pigments) or deep cultural resonance (salt) or at least entertaining quirkiness (punctuation marks, resignation letters). Shipping containers are important but simple and boring. The least interesting chapter in The Box covers container standardization, in which a whole bunch of people had boring meetings, wrote some things done, discovered many of the things they wrote down were dumb, wrote more things down, met with different people to have more meetings, published a standard that partly reflected the fixations of that one guy who is always involved in standards discussions, and then saw that standard be promptly ignored by the major market players. You may be wondering if that describes the whole book. It doesn't, but not because of the shipping containers. The Box is interesting because the process of economic change is interesting, and container shipping is almost entirely about business processes rather than technology. Levinson starts the substance of the book with a description of shipping before standardized containers. This was the most effective, and probably the most informative, chapter. Beyond some vague ideas picked up via cultural osmosis, I had no idea how cargo shipping worked. Levinson gives the reader a memorable feel for the sheer amount of physical labor involved in loading and unloading a ship with mixed cargo (what's called "breakbulk" cargo to distinguish it from bulk cargo like coal or wheat that fills an entire hold). It's not just the effort of hauling barrels, bales, or boxes with cranes or raw muscle power, although that is significant. It's also the need to touch every piece of cargo to move it, inventory it, warehouse it, and then load it on a truck or train. The idea of container shipping is widely attributed, including by Levinson, to Malcom McLean, a trucking magnate who became obsessed with the idea of what we now call intermodal transport: using the same container for goods on ships, railroads, and trucks so that the contents don't have to be unpacked and repacked at each transfer point. Levinson uses his career as an anchor for the story, from his acquisition of Pan-American Steamship Corporation to pursue his original idea (backed by private equity and debt, in a very modern twist), through his years running Sea-Land as the first successful major container shipper, and culminating in his disastrous attempted return to shipping by acquiring United States Lines. I am dubious of Great Man narratives in history books, and I think Levinson may be overselling McLean's role. Container shipping was an obvious idea that the industry had been talking about for decades. Even Levinson admits that, despite a few gestures at giving McLean central credit. Everyone involved in shipping understood that cargo handling was the most expensive and time-consuming part, and that if one could minimize cargo handling at the docks by loading and unloading full containers that didn't have to be opened, shipping costs would be much lower (and profits higher). The idea wasn't the hard part. McLean was the first person to pull it off at scale, thanks to some audacious economic risks and a willingness to throw sharp elbows and play politics, but it seems likely that someone else would have played that role if McLean hadn't existed. Container shipping didn't happen earlier because achieving that cost savings required a huge expenditure of capital and a major disruption of a transportation industry that wasn't interested in being disrupted. The ships had to be remodeled and eventually replaced; manufacturing had to change; railroad and trucking in theory had to change (in practice, intermodal transport; McLean's obsession, didn't happen at scale until much later); pricing had to be entirely reworked; logistical tracking of goods had to be done much differently; and significant amounts of extremely expensive equipment to load and unload heavy containers had to be designed, built, and installed. McLean's efforts proved the cost savings was real and compelling, but it still took two decades before the shipping industry reconstructed itself around containers. That interim period is where this history becomes a labor story, and that's where Levinson's biases become somewhat distracting. In the United States, loading and unloading of cargo ships was done by unionized longshoremen through a bizarre but complex and long-standing system of contract hiring. The cost savings of container shipping comes almost completely from the loss of work for longshoremen. It's a classic replacement of labor with capital; the work done by gangs of twenty or more longshoreman is instead done by a single crane operator at much higher speed and efficiency. The longshoreman unions therefore opposed containerization and launched numerous strikes and other labor actions to delay use of containers, force continued hiring that containers made unnecessary, or win buyouts and payoffs for current longshoremen. Levinson is trying to write a neutral history and occasionally shows some sympathy for longshoremen, but they still get the Luddite treatment in this book: the doomed reactionaries holding back progress. Longshoremen had a vigorous and powerful union that won better working conditions structured in ways that look absurd to outsiders, such as requiring that ships hire twice as many men as necessary so that half of them could get paid while not working. The unions also had a reputation for corruption that Levinson stresses constantly, and theft of breakbulk cargo during loading and warehousing was common. One of the interesting selling points for containers was that lossage from theft during shipping apparently decreased dramatically. It's obvious that the surface demand of the longshoremen unions, that either containers not be used or that just as many manual laborers be hired for container shipping as for earlier breakbulk shipping, was impossible, and that the profession as it existed in the 1950s was doomed. But beneath those facts, and the smoke screen of Levinson's obvious distaste for their unions, is a real question about what society owes workers whose jobs are eliminated by major shifts in business practices. That question of fairness becomes more pointed when one realizes that this shift was massively subsidized by US federal and local governments. McLean's Sea-Land benefited from direct government funding and subsidized navy surplus ships, massive port construction in New Jersey with public funds, and a sweetheart logistics contract from the US military to supply troops fighting the Vietnam War that was so generous that the return voyage was free and every container Sea-Land picked up from Japanese ports was pure profit. The US shipping industry was heavily government-supported, particularly in the early days when the labor conflicts were starting. Levinson notes all of this, but never draws the contrast between the massive support for shipping corporations and the complete lack of formal support for longshoremen. There are hard ethical questions about what society owes displaced workers even in a pure capitalist industry transformation, and this was very far from pure capitalism. The US government bankrolled large parts of the growth of container shipping, but the only way that longshoremen could get part of that money was through strikes to force payouts from private shipping companies. There are interesting questions of social and ethical history here that would require careful disentangling of the tendency of any group to oppose disruptive change and fairness questions of who gets government support and who doesn't. They will have to wait for another book; Levinson never mentions them. There were some things about this book that annoyed me, but overall it's a solid work of popular history and deserves its fame. Levinson's account is easy to follow, specific without being tedious, and backed by voluminous notes. It's not the most compelling story on its own merits; you have to have some interest in logistics and economics to justify reading the entire saga. But it's the sort of history that gives one a sense of the fractal complexity of any area of human endeavor, and I usually find those worth reading. Recommended if you like this sort of thing. Rating: 7 out of 10

20 December 2023

Melissa Wen: The Rainbow Treasure Map Talk: Advanced color management on Linux with AMD/Steam Deck.

Last week marked a major milestone for me: the AMD driver-specific color management properties reached the upstream linux-next! And to celebrate, I m happy to share the slides notes from my 2023 XDC talk, The Rainbow Treasure Map along with the individual recording that just dropped last week on youtube talk about happy coincidences!

Steam Deck Rainbow: Treasure Map & Magic Frogs While I may be bubbly and chatty in everyday life, the stage isn t exactly my comfort zone (hallway talks are more my speed). But the journey of developing the AMD color management properties was so full of discoveries that I simply had to share the experience. Witnessing the fantastic work of Jeremy and Joshua bring it all to life on the Steam Deck OLED was like uncovering magical ingredients and whipping up something truly enchanting. For XDC 2023, we split our Rainbow journey into two talks. My focus, The Rainbow Treasure Map, explored the new color features we added to the Linux kernel driver, diving deep into the hardware capabilities of AMD/Steam Deck. Joshua then followed with The Rainbow Frogs and showed the breathtaking color magic released on Gamescope thanks to the power unlocked by the kernel driver s Steam Deck color properties.

Packing a Rainbow into 15 Minutes I had so much to tell, but a half-slot talk meant crafting a concise presentation. To squeeze everything into 15 minutes (and calm my pre-talk jitters a bit!), I drafted and practiced those slides and notes countless times. So grab your map, and let s embark on the Rainbow journey together! Slide 1: The Rainbow Treasure Map - Advanced Color Management on Linux with AMD/SteamDeck Intro: Hi, I m Melissa from Igalia and welcome to the Rainbow Treasure Map, a talk about advanced color management on Linux with AMD/SteamDeck. Slide 2: List useful links for this technical talk Useful links: First of all, if you are not used to the topic, you may find these links useful.
  1. XDC 2022 - I m not an AMD expert, but - Melissa Wen
  2. XDC 2022 - Is HDR Harder? - Harry Wentland
  3. XDC 2022 Lightning - HDR Workshop Summary - Harry Wentland
  4. Color management and HDR documentation for FOSS graphics - Pekka Paalanen et al.
  5. Cinematic Color - 2012 SIGGRAPH course notes - Jeremy Selan
  6. AMD Driver-specific Properties for Color Management on Linux (Part 1) - Melissa Wen
Slide 3: Why do we need advanced color management on Linux? Context: When we talk about colors in the graphics chain, we should keep in mind that we have a wide variety of source content colorimetry, a variety of output display devices and also the internal processing. Users expect consistent color reproduction across all these devices. The userspace can use GPU-accelerated color management to get it. But this also requires an interface with display kernel drivers that is currently missing from the DRM/KMS framework. Slide 4: Describe our work on AMD driver-specific color properties Since April, I ve been bothering the DRM community by sending patchsets from the work of me and Joshua to add driver-specific color properties to the AMD display driver. In parallel, discussions on defining a generic color management interface are still ongoing in the community. Moreover, we are still not clear about the diversity of color capabilities among hardware vendors. To bridge this gap, we defined a color pipeline for Gamescope that fits the latest versions of AMD hardware. It delivers advanced color management features for gamut mapping, HDR rendering, SDR on HDR, and HDR on SDR. Slide 5: Describe the AMD/SteamDeck - our hardware AMD/Steam Deck hardware: AMD frequently releases new GPU and APU generations. Each generation comes with a DCN version with display hardware improvements. Therefore, keep in mind that this work uses the AMD Steam Deck hardware and its kernel driver. The Steam Deck is an APU with a DCN3.01 display driver, a DCN3 family. It s important to have this information since newer AMD DCN drivers inherit implementations from previous families but aldo each generation of AMD hardware may introduce new color capabilities. Therefore I recommend you to familiarize yourself with the hardware you are working on. Slide 6: Diagram with the three layers of the AMD display driver on Linux The AMD display driver in the kernel space: It consists of three layers, (1) the DRM/KMS framework, (2) the AMD Display Manager, and (3) the AMD Display Core. We extended the color interface exposed to userspace by leveraging existing DRM resources and connecting them using driver-specific functions for color property management. Slide 7: Three-layers diagram highlighting AMD Display Manager, DM - the layer that connects DC and DRM Bridging DC color capabilities and the DRM API required significant changes in the color management of AMD Display Manager - the Linux-dependent part that connects the AMD DC interface to the DRM/KMS framework. Slide 8: Three-layers diagram highlighting AMD Display Core, DC - the shared code The AMD DC is the OS-agnostic layer. Its code is shared between platforms and DCN versions. Examining this part helps us understand the AMD color pipeline and hardware capabilities, since the machinery for hardware settings and resource management are already there. Slide 9: Diagram of the AMD Display Core Next architecture with main elements and data flow The newest architecture for AMD display hardware is the AMD Display Core Next. Slide 10: Diagram of the AMD Display Core Next where only DPP and MPC blocks are highlighted In this architecture, two blocks have the capability to manage colors:
  • Display Pipe and Plane (DPP) - for pre-blending adjustments;
  • Multiple Pipe/Plane Combined (MPC) - for post-blending color transformations.
Let s see what we have in the DRM API for pre-blending color management. Slide 11: Blank slide with no content only a title 'Pre-blending: DRM plane' DRM plane color properties: This is the DRM color management API before blending. Nothing! Except two basic DRM plane properties: color_encoding and color_range for the input colorspace conversion, that is not covered by this work. Slide 12: Diagram with color capabilities and structures in AMD DC layer without any DRM plane color interface (before blending), only the DRM CRTC color interface for post blending In case you re not familiar with AMD shared code, what we need to do is basically draw a map and navigate there! We have some DRM color properties after blending, but nothing before blending yet. But much of the hardware programming was already implemented in the AMD DC layer, thanks to the shared code. Slide 13: Previous Diagram with a rectangle to highlight the empty space in the DRM plane interface that will be filled by AMD plane properties Still both the DRM interface and its connection to the shared code were missing. That s when the search begins! Slide 14: Color Pipeline Diagram with the plane color interface filled by AMD plane properties but without connections to AMD DC resources AMD driver-specific color pipeline: Looking at the color capabilities of the hardware, we arrive at this initial set of properties. The path wasn t exactly like that. We had many iterations and discoveries until reached to this pipeline. Slide 15: Color Pipeline Diagram connecting AMD plane degamma properties, LUT and TF, to AMD DC resources The Plane Degamma is our first driver-specific property before blending. It s used to linearize the color space from encoded values to light linear values. Slide 16: Describe plane degamma properties and hardware capabilities We can use a pre-defined transfer function or a user lookup table (in short, LUT) to linearize the color space. Pre-defined transfer functions for plane degamma are hardcoded curves that go to a specific hardware block called DPP Degamma ROM. It supports the following transfer functions: sRGB EOTF, BT.709 inverse OETF, PQ EOTF, and pure power curves Gamma 2.2, Gamma 2.4 and Gamma 2.6. We also have a one-dimensional LUT. This 1D LUT has four thousand ninety six (4096) entries, the usual 1D LUT size in the DRM/KMS. It s an array of drm_color_lut that goes to the DPP Gamma Correction block. Slide 17: Color Pipeline Diagram connecting AMD plane CTM property to AMD DC resources We also have now a color transformation matrix (CTM) for color space conversion. Slide 18: Describe plane CTM property and hardware capabilities It s a 3x4 matrix of fixed points that goes to the DPP Gamut Remap Block. Both pre- and post-blending matrices were previously gone to the same color block. We worked on detaching them to clear both paths. Now each CTM goes on its own way. Slide 19: Color Pipeline Diagram connecting AMD plane HDR multiplier property to AMD DC resources Next, the HDR Multiplier. HDR Multiplier is a factor applied to the color values of an image to increase their overall brightness. Slide 20: Describe plane HDR mult property and hardware capabilities This is useful for converting images from a standard dynamic range (SDR) to a high dynamic range (HDR). As it can range beyond [0.0, 1.0] subsequent transforms need to use the PQ(HDR) transfer functions. Slide 21: Color Pipeline Diagram connecting AMD plane shaper properties, LUT and TF, to AMD DC resources And we need a 3D LUT. But 3D LUT has a limited number of entries in each dimension, so we want to use it in a colorspace that is optimized for human vision. It means in a non-linear space. To deliver it, userspace may need one 1D LUT before 3D LUT to delinearize content and another one after to linearize content again for blending. Slide 22: Describe plane shaper properties and hardware capabilities The pre-3D-LUT curve is called Shaper curve. Unlike Degamma TF, there are no hardcoded curves for shaper TF, but we can use the AMD color module in the driver to build the following shaper curves from pre-defined coefficients. The color module combines the TF and the user LUT values into the LUT that goes to the DPP Shaper RAM block. Slide 23: Color Pipeline Diagram connecting AMD plane 3D LUT property to AMD DC resources Finally, our rockstar, the 3D LUT. 3D LUT is perfect for complex color transformations and adjustments between color channels. Slide 24: Describe plane 3D LUT property and hardware capabilities 3D LUT is also more complex to manage and requires more computational resources, as a consequence, its number of entries is usually limited. To overcome this restriction, the array contains samples from the approximated function and values between samples are estimated by tetrahedral interpolation. AMD supports 17 and 9 as the size of a single-dimension. Blue is the outermost dimension, red the innermost. Slide 25: Color Pipeline Diagram connecting AMD plane blend properties, LUT and TF, to AMD DC resources As mentioned, we need a post-3D-LUT curve to linearize the color space before blending. This is done by Blend TF and LUT. Slide 26: Describe plane blend properties and hardware capabilities Similar to shaper TF, there are no hardcoded curves for Blend TF. The pre-defined curves are the same as the Degamma block, but calculated by the color module. The resulting LUT goes to the DPP Blend RAM block. Slide 27: Color Pipeline Diagram  with all AMD plane color properties connect to AMD DC resources and links showing the conflict between plane and CRTC degamma Now we have everything connected before blending. As a conflict between plane and CRTC Degamma was inevitable, our approach doesn t accept that both are set at the same time. Slide 28: Color Pipeline Diagram connecting AMD CRTC gamma TF property to AMD DC resources We also optimized the conversion of the framebuffer to wire encoding by adding support to pre-defined CRTC Gamma TF. Slide 29: Describe CRTC gamma TF property and hardware capabilities Again, there are no hardcoded curves and TF and LUT are combined by the AMD color module. The same types of shaper curves are supported. The resulting LUT goes to the MPC Gamma RAM block. Slide 30: Color Pipeline Diagram with all AMD driver-specific color properties connect to AMD DC resources Finally, we arrived in the final version of DRM/AMD driver-specific color management pipeline. With this knowledge, you re ready to better enjoy the rainbow treasure of AMD display hardware and the world of graphics computing. Slide 31: SteamDeck/Gamescope Color Pipeline Diagram with rectangles labeling each block of the pipeline with the related AMD color property With this work, Gamescope/Steam Deck embraces the color capabilities of the AMD GPU. We highlight here how we map the Gamescope color pipeline to each AMD color block. Slide 32: Final slide. Thank you! Future works: The search for the rainbow treasure is not over! The Linux DRM subsystem contains many hidden treasures from different vendors. We want more complex color transformations and adjustments available on Linux. We also want to expose all GPU color capabilities from all hardware vendors to the Linux userspace. Thanks Joshua and Harry for this joint work and the Linux DRI community for all feedback and reviews. The amazing part of this work comes in the next talk with Joshua and The Rainbow Frogs! Any questions?
References:
  1. Slides of the talk The Rainbow Treasure Map.
  2. Youtube video of the talk The Rainbow Treasure Map.
  3. Patch series for AMD driver-specific color management properties (upstream Linux 6.8v).
  4. SteamDeck/Gamescope color management pipeline
  5. XDC 2023 website.
  6. Igalia website.

19 December 2023

Antoine Beaupr : (Re)introducing screentest

I have accidentally rewritten screentest, an old X11/GTK2 program that I was previously using to, well, test screens.

Screentest is dead It was removed from Debian in May 2023 but had already missed two releases (Debian 11 "bullseye" and 12 "bookworm") due to release critical bugs. The stated reason for removal was:
The package is orphaned and its upstream is no longer developed. It depends on gtk2, has a low popcon and no reverse dependencies.
So I had little hope to see this program back in Debian. The git repository shows little activity, the last being two years ago. Interestingly, I do not quite remember what it was testing, but I do remember it to find dead pixels, confirm native resolution, and various pixel-peeping. Here's a screenshot of one of the screentest screens: screentest screenshot showing a white-on-black checkered background, with some circles in the corners, shades of gray and colors in the middle Now, I think it's safe to assume this program is dead and buried, and anyways I'm running wayland now, surely there's something better? Well, no. Of course not. Someone would know about it and tell me before I go on a random coding spree in a fit of procrastination... riiight? At least, the Debconf video team didn't seem to know of any replacement. They actually suggested I just "invoke gstreamer directly" and "embrace the joy of shell scripting".

Screentest reborn So, I naively did exactly that and wrote a horrible shell script. Then I realized the next step was to write an command line parser and monitor geometry guessing, and thought "NOPE, THIS IS WHERE THE SHELL STOPS", and rewrote the whole thing in Python. Now, screentest lives as a ~400-line Python script, half of which is unit test data and command-line parsing.

Why screentest Some smarty pants is going to complain and ask why the heck one would need something like that (and, well, someone already did), so maybe I can lay down a list of use case:
  • testing color output, in broad terms (answering the question of "is it just me or this project really yellow?")
  • testing focus and keystone ("this looks blurry, can you find a nice sharp frame in that movie to adjust focus?")
  • test for native resolution and sharpness ("does this projector really support 4k for 30$? that sounds like bullcrap")
  • looking for dead pixels ("i have a new monitor, i hope it's intact")

What does screentest do? Screentest displays a series of "patterns" on screen. The list of patterns is actually hardcoded in the script, copy-pasted from this list from the videotestsrc gstreamer plugin, but you can pass any pattern supported by your gstreamer installation with --patterns. A list of patterns relevant to your installation is available with the gst-inspect-1.0 videotestsrc command. By default, screentest goes through all patterns. Each pattern runs indefinitely until the you close the window, then the next pattern starts. You can restrict to a subset of patterns, for example this would be a good test for dead pixels:
screentest --patterns black,white,red,green,blue
This would be a good sharpness test:
screentest --patterns pinwheel,spokes,checkers-1,checkers-2,checkers-4,checkers-8
A good generic test is the classic SMPTE color bars and is the first in the list, but you can run only that test with:
screentest --patterns smpte
(I will mention, by the way, that as a system administrator with decades of experience, it is nearly impossible to type SMPTE without first typing SMTP and re-typing it again a few times before I get it right. I fully expect this post to have numerous typos.)
Here's an example of the SMPTE pattern from Wikipedia: SMPTE color bars For multi-monitor setups, screentest also supports specifying which output to use as a native resolution, with --output. Failing that, it will try to look at the outputs and use the first it will find. If it fails to find anything, you can specify a resolution with --resolution WIDTHxHEIGHT. I have tried to make it go full screen by default, but stumbled a bug in Sway that crashes gst-launch. If your Wayland compositor supports it, you can possibly enable full screen with --sink waylandsink fullscreen=true. Otherwise it will create a new window that you will have to make fullscreen yourself. For completeness, there's also an --audio flag that will emit the classic "drone", a sine wave at 440Hz at 40% volume (the audiotestsrc gstreamer plugin. And there's a --overlay-name option to show the pattern name, in case you get lost and want to start with one of them again.

How this works Most of the work is done by gstreamer. The script merely generates a pipeline and calls gst-launch to show the output. That both limits what it can do but also makes it much easier to use than figuring out gst-launch. There might be some additional patterns that could be useful, but I think those are better left to gstreamer. I, for example, am somewhat nostalgic of the Philips circle pattern that used to play for TV stations that were off-air in my area. But that, in my opinion, would be better added to the gstreamer plugin than into a separate thing. The script shows which command is being ran, so it's a good introduction to gstreamer pipelines. Advanced users (and the video team) will possibly not need screentest and will design their own pipelines with their own tools. I've previously worked with ffmpeg pipelines (in another such procrastinated coding spree, video-proxy-magic), and I found gstreamer more intuitive, even though it might be slightly less powerful. In retrospect, I should probably have picked a new name, to avoid crashing the namespace already used by the project, which is now on GitHub. Who knows, it might come back to life after this blog post; it would not be the first time. For now, the project lives along side the rest of my scripts collection but if there's sufficient interest, I might move it to its own git repositories. Comments, feedback, contributions are as usual welcome. And naturally, if you know something better for this kind of stuff, I'm happy to learn more about your favorite tool! So now I have finally found something to test my projector, which will likely confirm what I've already known all along: that it's kind of a piece of crap and I need to get a proper one.

13 December 2023

Jonathan Dowland: equivalence problems with StreamGraph

I've been tackling an equivalence problem with rewritten programs in StrIoT, our proof-of-concept stream-processing system. The StrIoT Logical Optimiser applies a set of rewrite rules to a stream-processing program, generating a set of variants that can be reasoned about, ranked, and deployed. The problem I've been tackling is that a variant may appear to be semantically equivalent to another, but compare (with ==) as distinct. The issue relates to the design of our data-type representing programs, in particular, a consequence of our choice to outsource the structural aspect to a 3rd-party library (Algebra.Graph). The Graph library deems nodes that compare as equivalent (again with ==) to be the same. Since a stream-processing program may contain many operators which are equivalent, but distinct, we needed to add a field to our payload type to differentiate them: so we opted for an Integer field, vertexId (something I've described as a "wart" elsewhere) Here's a simplified example of our existing payload type, StreamVertex:
data StreamVertex = StreamVertex
      vertexId   :: Int
    , operator   :: StreamOperator
    , parameters :: [ExpQ]
    , intype     :: String
    , outtype    :: String
     
A rewrite rule might introduce or eliminate operators from a stream-processing program. For example, consider the rule which "hoists" a filter upstream from a merge operator. In pseudo-Haskell,
streamFilter p . streamMerge [a , b, ...]
=>
streamMerge [ streamFilter p a
            , streamFilter p b
            , ...]
The original streamFilter is removed, and new streamFilters are introduced, one per stream arriving at streamMerge. In general, rules may need to synthesise new operators, and thus new vertexIds. Another rewrite rule might perform the reverse operation. But the individual rules operate in isolation: and so, the program variant that results after applying a rule and then applying an inverse rule may not have the same vertexIds, or the same order of vertexIds, as the original program. I thought of the outline of two possible solutions to this. "well-numbered" StreamGraphs The first was to encode (and enforce) some rules about how vertexIds are used. If they always began from (say) 1, and were strictly-ascending from the source operator(s), and rewrite rules guaranteed that a "well numbered" input would be "well numbered" after rewriting, this would be sufficient to rule out a rewritten-but-semantically-equivalent program being considered distinct. The trouble with this approach is using properties of a numerical system built around vertexId as a stand-in for the real structural problem. I was not sure I could prove both that the stand-in system was sound and that it was a proper analogue for the underlying structural issue. It feels to me more that the choice to use an external library to encode the structure of a stream-processing program was the issue: the structure itself is a fundamental part of the semantics of the program. What if we had encoded the structure of programs within the same data-type? alternative data-type StrIoT programs are trees. The root is the sink node: there is always exactly one. There can be multiple source (leaf nodes), but they always converge. Operators can have multiple inputs (including zero). The root node has no output, but all other operators have exactly one. I explored transforming StreamVertex into a tree by adding a field representing incoming streams, and dispensing with Graph and vertexId. Something like this
data StreamProg = StreamProg StreamOperator [Exp] String String [StreamProg]
A uni-directional transformation from Graph StreamVertex to StreamProg is all that's needed to implement something like ==, so we don't need to keep track of vertexId mappings. Unfortunately, we can't fix the actual Eq (Graph StreamVertex) implementation this way: it delegates to Eq StreamVertex, and we just don't have enough information to fix the problem at that level. But, we can write a separate graphEq and use that instead where we need to. could I go further? Spoiler: I haven't. But I've been sorely tempted. We still have a separate StreamOperator type, which it would be nice to fold in; and we still have to use a list around the incoming nodes, since different operators accept different numbers of incoming streams. It would be better to encode the correct valences in the type. In 2020 I explored iteratively reducing the StreamVertex data-type to try and get it as close as possible to the ideal end-user API: simple functions. I wrote about one step along that path in Template Haskell and Stream-processing programs, but concluded that, since this was not my main PhD focus, I wouldn't go further. But it was nagging at my subconcious ever since. I allowed myself a couple of days exploring some advanced concepts including typed Template Haskell (that has had some developments since 2020), generalised abstract data types (GADTs) and more generic programming to see what could be achieved. I'll summarise all that in the next blog post.

Melissa Wen: 15 Tips for Debugging Issues in the AMD Display Kernel Driver

A self-help guide for examining and debugging the AMD display driver within the Linux kernel/DRM subsystem. It s based on my experience as an external developer working on the driver, and are shared with the goal of helping others navigate the driver code. Acknowledgments: These tips were gathered thanks to the countless help received from AMD developers during the driver development process. The list below was obtained by examining open source code, reviewing public documentation, playing with tools, asking in public forums and also with the help of my former GSoC mentor, Rodrigo Siqueira.

Pre-Debugging Steps: Before diving into an issue, it s crucial to perform two essential steps: 1) Check the latest changes: Ensure you re working with the latest AMD driver modifications located in the amd-staging-drm-next branch maintained by Alex Deucher. You may also find bug fixes for newer kernel versions on branches that have the name pattern drm-fixes-<date>. 2) Examine the issue tracker: Confirm that your issue isn t already documented and addressed in the AMD display driver issue tracker. If you find a similar issue, you can team up with others and speed up the debugging process.

Understanding the issue: Do you really need to change this? Where should you start looking for changes? 3) Is the issue in the AMD kernel driver or in the userspace?: Identifying the source of the issue is essential regardless of the GPU vendor. Sometimes this can be challenging so here are some helpful tips:
  • Record the screen: Capture the screen using a recording app while experiencing the issue. If the bug appears in the capture, it s likely a userspace issue, not the kernel display driver.
  • Analyze the dmesg log: Look for error messages related to the display driver in the dmesg log. If the error message appears before the message [drm] Display Core v... , it s not likely a display driver issue. If this message doesn t appear in your log, the display driver wasn t fully loaded and you will see a notification that something went wrong here.
4) AMD Display Manager vs. AMD Display Core: The AMD display driver consists of two components:
  • Display Manager (DM): This component interacts directly with the Linux DRM infrastructure. Occasionally, issues can arise from misinterpretations of DRM properties or features. If the issue doesn t occur on other platforms with the same AMD hardware - for example, only happens on Linux but not on Windows - it s more likely related to the AMD DM code.
  • Display Core (DC): This is the platform-agnostic part responsible for setting and programming hardware features. Modifications to the DC usually require validation on other platforms, like Windows, to avoid regressions.
5) Identify the DC HW family: Each AMD GPU has variations in its hardware architecture. Features and helpers differ between families, so determining the relevant code for your specific hardware is crucial.
  • Find GPU product information in Linux/AMD GPU documentation
  • Check the dmesg log for the Display Core version (since this commit in Linux kernel 6.3v). For example:
    • [drm] Display Core v3.2.241 initialized on DCN 2.1
    • [drm] Display Core v3.2.237 initialized on DCN 3.0.1

Investigating the relevant driver code: Keep from letting unrelated driver code to affect your investigation. 6) Narrow the code inspection down to one DC HW family: the relevant code resides in a directory named after the DC number. For example, the DCN 3.0.1 driver code is located at drivers/gpu/drm/amd/display/dc/dcn301. We all know that the AMD s shared code is huge and you can use these boundaries to rule out codes unrelated to your issue. 7) Newer families may inherit code from older ones: you can find dcn301 using code from dcn30, dcn20, dcn10 files. It s crucial to verify which hooks and helpers your driver utilizes to investigate the right portion. You can leverage ftrace for supplemental validation. To give an example, it was useful when I was updating DCN3 color mapping to correctly use their new post-blending color capabilities, such as: Additionally, you can use two different HW families to compare behaviours. If you see the issue in one but not in the other, you can compare the code and understand what has changed and if the implementation from a previous family doesn t fit well the new HW resources or design. You can also count on the help of the community on the Linux AMD issue tracker to validate your code on other hardware and/or systems. This approach helped me debug a 2-year-old issue where the cursor gamma adjustment was incorrect in DCN3 hardware, but working correctly for DCN2 family. I solved the issue in two steps, thanks for community feedback and validation: 8) Check the hardware capability screening in the driver: You can currently find a list of display hardware capabilities in the drivers/gpu/drm/amd/display/dc/dcn*/dcn*_resource.c file. More precisely in the dcn*_resource_construct() function. Using DCN301 for illustration, here is the list of its hardware caps:
	/*************************************************
	 *  Resource + asic cap harcoding                *
	 *************************************************/
	pool->base.underlay_pipe_index = NO_UNDERLAY_PIPE;
	pool->base.pipe_count = pool->base.res_cap->num_timing_generator;
	pool->base.mpcc_count = pool->base.res_cap->num_timing_generator;
	dc->caps.max_downscale_ratio = 600;
	dc->caps.i2c_speed_in_khz = 100;
	dc->caps.i2c_speed_in_khz_hdcp = 5; /*1.4 w/a enabled by default*/
	dc->caps.max_cursor_size = 256;
	dc->caps.min_horizontal_blanking_period = 80;
	dc->caps.dmdata_alloc_size = 2048;
	dc->caps.max_slave_planes = 2;
	dc->caps.max_slave_yuv_planes = 2;
	dc->caps.max_slave_rgb_planes = 2;
	dc->caps.is_apu = true;
	dc->caps.post_blend_color_processing = true;
	dc->caps.force_dp_tps4_for_cp2520 = true;
	dc->caps.extended_aux_timeout_support = true;
	dc->caps.dmcub_support = true;
	/* Color pipeline capabilities */
	dc->caps.color.dpp.dcn_arch = 1;
	dc->caps.color.dpp.input_lut_shared = 0;
	dc->caps.color.dpp.icsc = 1;
	dc->caps.color.dpp.dgam_ram = 0; // must use gamma_corr
	dc->caps.color.dpp.dgam_rom_caps.srgb = 1;
	dc->caps.color.dpp.dgam_rom_caps.bt2020 = 1;
	dc->caps.color.dpp.dgam_rom_caps.gamma2_2 = 1;
	dc->caps.color.dpp.dgam_rom_caps.pq = 1;
	dc->caps.color.dpp.dgam_rom_caps.hlg = 1;
	dc->caps.color.dpp.post_csc = 1;
	dc->caps.color.dpp.gamma_corr = 1;
	dc->caps.color.dpp.dgam_rom_for_yuv = 0;
	dc->caps.color.dpp.hw_3d_lut = 1;
	dc->caps.color.dpp.ogam_ram = 1;
	// no OGAM ROM on DCN301
	dc->caps.color.dpp.ogam_rom_caps.srgb = 0;
	dc->caps.color.dpp.ogam_rom_caps.bt2020 = 0;
	dc->caps.color.dpp.ogam_rom_caps.gamma2_2 = 0;
	dc->caps.color.dpp.ogam_rom_caps.pq = 0;
	dc->caps.color.dpp.ogam_rom_caps.hlg = 0;
	dc->caps.color.dpp.ocsc = 0;
	dc->caps.color.mpc.gamut_remap = 1;
	dc->caps.color.mpc.num_3dluts = pool->base.res_cap->num_mpc_3dlut; //2
	dc->caps.color.mpc.ogam_ram = 1;
	dc->caps.color.mpc.ogam_rom_caps.srgb = 0;
	dc->caps.color.mpc.ogam_rom_caps.bt2020 = 0;
	dc->caps.color.mpc.ogam_rom_caps.gamma2_2 = 0;
	dc->caps.color.mpc.ogam_rom_caps.pq = 0;
	dc->caps.color.mpc.ogam_rom_caps.hlg = 0;
	dc->caps.color.mpc.ocsc = 1;
	dc->caps.dp_hdmi21_pcon_support = true;
	/* read VBIOS LTTPR caps */
	if (ctx->dc_bios->funcs->get_lttpr_caps)  
		enum bp_result bp_query_result;
		uint8_t is_vbios_lttpr_enable = 0;
		bp_query_result = ctx->dc_bios->funcs->get_lttpr_caps(ctx->dc_bios, &is_vbios_lttpr_enable);
		dc->caps.vbios_lttpr_enable = (bp_query_result == BP_RESULT_OK) && !!is_vbios_lttpr_enable;
	 
	if (ctx->dc_bios->funcs->get_lttpr_interop)  
		enum bp_result bp_query_result;
		uint8_t is_vbios_interop_enabled = 0;
		bp_query_result = ctx->dc_bios->funcs->get_lttpr_interop(ctx->dc_bios, &is_vbios_interop_enabled);
		dc->caps.vbios_lttpr_aware = (bp_query_result == BP_RESULT_OK) && !!is_vbios_interop_enabled;
	 
Keep in mind that the documentation of color capabilities are available at the Linux kernel Documentation.

Understanding the development history: What has brought us to the current state? 9) Pinpoint relevant commits: Use git log and git blame to identify commits targeting the code section you re interested in. 10) Track regressions: If you re examining the amd-staging-drm-next branch, check for regressions between DC release versions. These are defined by DC_VER in the drivers/gpu/drm/amd/display/dc/dc.h file. Alternatively, find a commit with this format drm/amd/display: 3.2.221 that determines a display release. It s useful for bisecting. This information helps you understand how outdated your branch is and identify potential regressions. You can consider each DC_VER takes around one week to be bumped. Finally, check testing log of each release in the report provided on the amd-gfx mailing list, such as this one Tested-by: Daniel Wheeler:

Reducing the inspection area: Focus on what really matters. 11) Identify involved HW blocks: This helps isolate the issue. You can find more information about DCN HW blocks in the DCN Overview documentation. In summary:
  • Plane issues are closer to HUBP and DPP.
  • Blending/Stream issues are closer to MPC, OPP and OPTC. They are related to DRM CRTC subjects.
This information was useful when debugging a hardware rotation issue where the cursor plane got clipped off in the middle of the screen. Finally, the issue was addressed by two patches: 12) Issues around bandwidth (glitches) and clocks: May be affected by calculations done in these HW blocks and HW specific values. The recalculation equations are found in the DML folder. DML stands for Display Mode Library. It s in charge of all required configuration parameters supported by the hardware for multiple scenarios. See more in the AMD DC Overview kernel docs. It s a math library that optimally configures hardware to find the best balance between power efficiency and performance in a given scenario. Finding some clk variables that affect device behavior may be a sign of it. It s hard for a external developer to debug this part, since it involves information from HW specs and firmware programming that we don t have access. The best option is to provide all relevant debugging information you have and ask AMD developers to check the values from your suspicions.
  • Do a trick: If you suspect the power setup is degrading performance, try setting the amount of power supplied to the GPU to the maximum and see if it affects the system behavior with this command: sudo bash -c "echo high > /sys/class/drm/card0/device/power_dpm_force_performance_level"
I learned it when debugging glitches with hardware cursor rotation on Steam Deck. My first attempt was changing the clock calculation. In the end, Rodrigo Siqueira proposed the right solution targeting bandwidth in two steps:

Checking implicit programming and hardware limitations: Bring implicit programming to the level of consciousness and recognize hardware limitations. 13) Implicit update types: Check if the selected type for atomic update may affect your issue. The update type depends on the mode settings, since programming some modes demands more time for hardware processing. More details in the source code:
/* Surface update type is used by dc_update_surfaces_and_stream
 * The update type is determined at the very beginning of the function based
 * on parameters passed in and decides how much programming (or updating) is
 * going to be done during the call.
 *
 * UPDATE_TYPE_FAST is used for really fast updates that do not require much
 * logical calculations or hardware register programming. This update MUST be
 * ISR safe on windows. Currently fast update will only be used to flip surface
 * address.
 *
 * UPDATE_TYPE_MED is used for slower updates which require significant hw
 * re-programming however do not affect bandwidth consumption or clock
 * requirements. At present, this is the level at which front end updates
 * that do not require us to run bw_calcs happen. These are in/out transfer func
 * updates, viewport offset changes, recout size changes and pixel
depth changes.
 * This update can be done at ISR, but we want to minimize how often
this happens.
 *
 * UPDATE_TYPE_FULL is slow. Really slow. This requires us to recalculate our
 * bandwidth and clocks, possibly rearrange some pipes and reprogram
anything front
 * end related. Any time viewport dimensions, recout dimensions,
scaling ratios or
 * gamma need to be adjusted or pipe needs to be turned on (or
disconnected) we do
 * a full update. This cannot be done at ISR level and should be a rare event.
 * Unless someone is stress testing mpo enter/exit, playing with
colour or adjusting
 * underscan we don't expect to see this call at all.
 */
enum surface_update_type  
UPDATE_TYPE_FAST, /* super fast, safe to execute in isr */
UPDATE_TYPE_MED,  /* ISR safe, most of programming needed, no bw/clk change*/
UPDATE_TYPE_FULL, /* may need to shuffle resources */
 ;

Using tools: Observe the current state, validate your findings, continue improvements. 14) Use AMD tools to check hardware state and driver programming: help on understanding your driver settings and checking the behavior when changing those settings.
  • DC Visual confirmation: Check multiple planes and pipe split policy.
  • DTN logs: Check display hardware state, including rotation, size, format, underflow, blocks in use, color block values, etc.
  • UMR: Check ASIC info, register values, KMS state - links and elements (framebuffers, planes, CRTCs, connectors). Source: UMR project documentation
15) Use generic DRM/KMS tools:
  • IGT test tools: Use generic KMS tests or develop your own to isolate the issue in the kernel space. Compare results across different GPU vendors to understand their implementations and find potential solutions. Here AMD also has specific IGT tests for its GPUs that is expect to work without failures on any AMD GPU. You can check results of HW-specific tests using different display hardware families or you can compare expected differences between the generic workflow and AMD workflow.
  • drm_info: This tool summarizes the current state of a display driver (capabilities, properties and formats) per element of the DRM/KMS workflow. Output can be helpful when reporting bugs.

Don t give up! Debugging issues in the AMD display driver can be challenging, but by following these tips and leveraging available resources, you can significantly improve your chances of success. Worth mentioning: This blog post builds upon my talk, I m not an AMD expert, but presented at the 2022 XDC. It shares guidelines that helped me debug AMD display issues as an external developer of the driver. Open Source Display Driver: The Linux kernel/AMD display driver is open source, allowing you to actively contribute by addressing issues listed in the official tracker. Tackling existing issues or resolving your own can be a rewarding learning experience and a valuable contribution to the community. Additionally, the tracker serves as a valuable resource for finding similar bugs, troubleshooting tips, and suggestions from AMD developers. Finally, it s a platform for seeking help when needed. Remember, contributing to the open source community through issue resolution and collaboration is mutually beneficial for everyone involved.

2 December 2023

Dirk Eddelbuettel: tidyCpp 0.0.7 on CRAN: Maintenance

A maintenance release of the tidyCpp package arrived on CRAN this morning. The packages offers a clean C++ layer (as well as one small C++ helper class) on top of the C API for R which aims to make use of this robust (if awkward) C API a little easier and more consistent. See the vignette for motivating examples. This release follows a number of other releases this week in accomodating the recently added -Wformat -Wformat-security from the development branch of R. It also includes a new example snippet illustrating creation of a numeric matrix. The NEWS entry follows.

Changes in tidyCpp version 0.0.7 (2023-11-30)
  • Add an example for a numeric matrix creator
  • Update the continuous integration setup
  • Accomodate print format warnings from r-devel

Thanks to my CRANberries, there is also a diffstat report for this release. For questions, suggestions, or issues please use the issue tracker at the GitHub repo. If you like this or other open-source work I do, you can now sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

26 November 2023

Niels Thykier: Providing online reference documentation for debputy

I do not think seasoned Debian contributors quite appreciate how much knowledge we have picked up and internalized. As an example, when I need to look up documentation for debhelper, I generally know which manpage to look in. I suspect most long time contributors would be able to a similar thing (maybe down 2-3 manpages). But new contributors does not have the luxury of years of experience. This problem is by no means unique to debhelper. One thing that debhelper does very well, is that it is hard for users to tell where a addon "starts" and debhelper "ends". It is clear you use addons, but the transition in and out of third party provided tools is generally smooth. This is a sign that things "just work(tm)". Except when it comes to documentation. Here, debhelper's static documentation does not include documentation for third party tooling. If you think from a debhelper maintainer's perspective, this seems obvious. Embedding documentation for all the third-party code would be very hard work, a layer-violation, etc.. But from a user perspective, we should not have to care "who" provides "what". As as user, I want to understand how this works and the more hoops I have to jump through to get that understanding, the more frustrated I will be with the toolstack. With this, I came to the conclusion that the best way to help users and solve the problem of finding the documentation was to provide "online documentation". It should be possible to ask debputy, "What attributes can I use in install-man?" or "What does path-metadata do?". Additionally, the lookup should work the same no matter if debputy provided the feature or some third-party plugin did. In the future, perhaps also other types of documentation such as tutorials or how-to guides. Below, I have some tentative results of my work so far. There are some improvements to be done. Notably, the commands for these documentation features are still treated a "plugin" subcommand features and should probably have its own top level "ask-me-anything" subcommand in the future.
Automatic discard rules Since the introduction of install rules, debputy has included an automatic filter mechanism that prunes out unwanted content. In 0.1.9, these filters have been named "Automatic discard rules" and you can now ask debputy to list them.
$ debputy plugin list automatic-discard-rules
+-----------------------+-------------+
  Name                    Provided By  
+-----------------------+-------------+
  python-cache-files      debputy      
  la-files                debputy      
  backup-files            debputy      
  version-control-paths   debputy      
  gnu-info-dir-file       debputy      
  debian-dir              debputy      
  doxygen-cruft-files     debputy      
+-----------------------+-------------+
For these rules, the provider can both provide a description but also an example of their usage.
$ debputy plugin show automatic-discard-rules la-files
Automatic Discard Rule: la-files
================================
Documentation: Discards any .la files beneath /usr/lib
Example
-------
    /usr/lib/libfoo.la        << Discarded (directly by the rule)
    /usr/lib/libfoo.so.1.0.0
The example is a live example. That is, the provider will provide debputy with a scenario and the expected outcome of that scenario. Here is the concrete code in debputy that registers this example:
api.automatic_discard_rule(
    "la-files",
    _debputy_prune_la_files,
    rule_reference_documentation="Discards any .la files beneath /usr/lib",
    examples=automatic_discard_rule_example(
        "usr/lib/libfoo.la",
        ("usr/lib/libfoo.so.1.0.0", False),
    ),
)
When showing the example, debputy will validate the example matches what the plugin provider intended. Lets say I was to introduce a bug in the code, so that the discard rule no longer worked. Then debputy would start to show the following:
# Output if the code or example is broken
$ debputy plugin show automatic-discard-rules la-files
[...]
Automatic Discard Rule: la-files
================================
Documentation: Discards any .la files beneath /usr/lib
Example
-------
    /usr/lib/libfoo.la        !! INCONSISTENT (code: keep, example: discard)
    /usr/lib/libfoo.so.1.0.0
debputy: warning: The example was inconsistent. Please file a bug against the plugin debputy
Obviously, it would be better if this validation could be added directly as a plugin test, so the CI pipeline would catch it. That is one my personal TODO list. :) One final remark about automatic discard rules before moving on. In 0.1.9, debputy will also list any path automatically discarded by one of these rules in the build output to make sure that the automatic discard rule feature is more discoverable.
Plugable manifest rules like the install rule In the manifest, there are several places where rules can be provided by plugins. To make life easier for users, debputy can now since 0.1.8 list all provided rules:
$ debputy plugin list plugable-manifest-rules
+-------------------------------+------------------------------+-------------+
  Rule Name                       Rule Type                      Provided By  
+-------------------------------+------------------------------+-------------+
  install                         InstallRule                    debputy      
  install-docs                    InstallRule                    debputy      
  install-examples                InstallRule                    debputy      
  install-doc                     InstallRule                    debputy      
  install-example                 InstallRule                    debputy      
  install-man                     InstallRule                    debputy      
  discard                         InstallRule                    debputy      
  move                            TransformationRule             debputy      
  remove                          TransformationRule             debputy      
  [...]                           [...]                          [...]        
  remove                          DpkgMaintscriptHelperCommand   debputy      
  rename                          DpkgMaintscriptHelperCommand   debputy      
  cross-compiling                 ManifestCondition              debputy      
  can-execute-compiled-binaries   ManifestCondition              debputy      
  run-build-time-tests            ManifestCondition              debputy      
  [...]                           [...]                          [...]        
+-------------------------------+------------------------------+-------------+
(Output trimmed a bit for space reasons) And you can then ask debputy to describe any of these rules:
$ debputy plugin show plugable-manifest-rules install
Generic install ( install )
===========================
The generic  install  rule can be used to install arbitrary paths into packages
and is *similar* to how  dh_install  from debhelper works.  It is a two "primary" uses.
  1) The classic "install into directory" similar to the standard  dh_install 
  2) The "install as" similar to  dh-exec 's  foo => bar  feature.
Attributes:
 -  source  (conditional): string
    sources  (conditional): List of string
   A path match ( source ) or a list of path matches ( sources ) defining the
   source path(s) to be installed. [...]
 -  dest-dir  (optional): string
   A path defining the destination *directory*. [...]
 -  into  (optional): string or a list of string
   A path defining the destination *directory*. [...]
 -  as  (optional): string
   A path defining the path to install the source as. [...]
 -  when  (optional): manifest condition (string or mapping of string)
   A condition as defined in [Conditional rules](https://salsa.debian.org/debian/debputy/-/blob/main/MANIFEST-FORMAT.md#Conditional rules).
This rule enforces the following restrictions:
 - The rule must use exactly one of:  source ,  sources 
 - The attribute  as  cannot be used with any of:  dest-dir ,  sources 
[...]
(Output trimmed a bit for space reasons) All the attributes and restrictions are auto-computed by debputy from information provided by the plugin. The associated documentation for each attribute is supplied by the plugin itself, The debputy API validates that all attributes are covered and the documentation does not describe non-existing fields. This ensures that you as a plugin provider never forget to document new attributes when you add them later. The debputy API for manifest rules are not quite stable yet. So currently only debputy provides rules here. However, it is my intention to lift that restriction in the future. I got the idea of supporting online validated examples when I was building this feature. However, sadly, I have not gotten around to supporting it yet.
Manifest variables like PACKAGE I also added a similar documentation feature for manifest variables such as PACKAGE . When I implemented this, I realized listing all manifest variables by default would probably be counter productive to new users. As an example, if you list all variables by default it would include DEB_HOST_MULTIARCH (the most common case) side-by-side with the the much less used DEB_BUILD_MULTIARCH and the even lessor used DEB_TARGET_MULTIARCH variable. Having them side-by-side implies they are of equal importance, which they are not. As an example, the ballpark number of unique packages for which DEB_TARGET_MULTIARCH is useful can be counted on two hands (and maybe two feet if you consider gcc-X distinct from gcc-Y). This is one of the cases, where experience makes us blind. Many of us probably have the "show me everything and I will find what I need" mentality. But that requires experience to be able to pull that off - especially if all alternatives are presented as equals. The cross-building terminology has proven to notoriously match poorly to people's expectation. Therefore, I took a deliberate choice to reduce the list of shown variables by default and in the output explicitly list what filters were active. In the current version of debputy (0.1.9), the listing of manifest-variables look something like this:
$ debputy plugin list manifest-variables
+----------------------------------+----------------------------------------+------+-------------+
  Variable (use via:   NAME  )   Value                                    Flag   Provided by  
+----------------------------------+----------------------------------------+------+-------------+
  DEB_HOST_ARCH                      amd64                                           debputy      
  [... other DEB_HOST_* vars ...]    [...]                                           debputy      
  DEB_HOST_MULTIARCH                 x86_64-linux-gnu                                debputy      
  DEB_SOURCE                         debputy                                         debputy      
  DEB_VERSION                        0.1.8                                           debputy      
  DEB_VERSION_EPOCH_UPSTREAM         0.1.8                                           debputy      
  DEB_VERSION_UPSTREAM               0.1.8                                           debputy      
  DEB_VERSION_UPSTREAM_REVISION      0.1.8                                           debputy      
  PACKAGE                            <package-name>                                  debputy      
  path:BASH_COMPLETION_DIR           /usr/share/bash-completion/completions          debputy      
+----------------------------------+----------------------------------------+------+-------------+
+-----------------------+--------+-------------------------------------------------------+
  Variable type           Value    Option                                                 
+-----------------------+--------+-------------------------------------------------------+
  Token variables         hidden   --show-token-variables OR --show-all-variables         
  Special use variables   hidden   --show-special-case-variables OR --show-all-variables  
+-----------------------+--------+-------------------------------------------------------+
I will probably tweak the concrete listing in the future. Personally, I am considering to provide short-hands variables for some of the DEB_HOST_* variables and then hide the DEB_HOST_* group from the default view as well. Maybe something like ARCH and MULTIARCH, which would default to their DEB_HOST_* counter part. This variable could then have extended documentation that high lights DEB_HOST_<X> as its source and imply that there are special cases for cross-building where you might need DEB_BUILD_<X> or DEB_TARGET_<X>. Speaking of variable documentation, you can also lookup the documentation for a given manifest variable:
$ debputy plugin show manifest-variables path:BASH_COMPLETION_DIR
Variable: path:BASH_COMPLETION_DIR
==================================
Documentation: Directory to install bash completions into
Resolved: /usr/share/bash-completion/completions
Plugin: debputy
This was my update on online reference documentation for debputy. I hope you found it useful. :)
Thanks On a closing note, I would like to thanks Jochen Sprickerhof, Andres Salomon, Paul Gevers for their recent contributions to debputy. Jochen and Paul provided a number of real world cases where debputy would crash or not work, which have now been fixed. Andres and Paul also provided corrections to the documentation.

20 November 2023

Russ Allbery: Review: The Exiled Fleet

Review: The Exiled Fleet, by J.S. Dewes
Series: Divide #2
Publisher: Tor
Copyright: 2021
ISBN: 1-250-23635-5
Format: Kindle
Pages: 421
The Exiled Fleet is far-future interstellar military SF. It is a direct sequel to The Last Watch. You don't want to start here. The Last Watch took a while to get going, but it ended with some fascinating world-building and a suitably enormous threat. I was hoping Dewes would carry that momentum into the second book. I was disappointed; instead, The Exiled Fleet starts with interpersonal angst and wallowing and takes an annoyingly long time to build up narrative tension again. The world-building of the first book looked outward, towards aliens and strange technology and stranger physics, while setting up contributing problems on the home front. The Exiled Fleet pivots inwards, both in terms of world-building and in terms of character introspection. Neither of those worked as well for me. There's nothing wrong with the revelations here about human power structures and the politics that the Sentinels have been missing at the edge of space, but it also felt like a classic human autocracy without much new to offer in either wee thinky bits or plot structure. We knew most of shape from the start of the first book: Cavalon's grandfather is evil, human society is run as an oligarchy, and everything is trending authoritarian. Once the action started, I was entertained but not gripped the way that I was when reading The Last Watch. Dewes makes a brief attempt to tap into the morally complex question of the military serving as a brake on tyranny, but then does very little with it. Instead, everything is excessively personal, turning the political into less of a confrontation of ideologies or ethics and more a story of family abuse and rebellion. There is even more psychodrama in this book than there was in the previous book. I found it exhausting. Rake is barely functional after the events of the previous book and pushing herself way too hard at the start of this one. Cavalon regresses considerably and starts falling apart again. There's a lot of moping, a lot of angst, and a lot of characters berating themselves and occasionally each other. It was annoying enough that I took a couple of weeks break from this book in the middle before I could work up the enthusiasm to finish it. Some of this is personal preference. My favorite type of story is competence porn: details about something esoteric and satisfyingly complex, a challenge to overcome, and a main character who deploys their expertise to overcome that challenge in a way that shows they generally have their shit together. I can enjoy other types of stories, but that's the story I'll keep reaching for. Other people prefer stories about fuck-ups and walking disasters, people who barely pull together enough to survive the plot (or sometimes not even that). There's nothing wrong with that, and neither approach is right or wrong, but my tolerance for that story is usually lot lower. I think Dewes is heading towards the type of story in which dysfunctional characters compensate for each other's flaws in order to keep each other going, and intellectually I can see the appeal. But it's not my thing, and when the main characters are falling apart and the supporting characters project considerably more competence, I wish the story had different protagonists. It didn't help that this is in theory military SF, but Dewes does not seem to want to deploy any of the support framework of the military to address any of her characters' problems. This book is a lot of Rake and Cavalon dragging each other through emotional turmoil while coming to terms with Cavalon's family. I liked their dynamic in the first book when it felt more like Rake showing leadership skills. Here, it turns into something closer to found family in ways that seemed wildly inconsistent with the military structure, and while I'm normally not one to defend hierarchical discipline, I felt like Rake threw out the only structure she had to handle the thousands of other people under her command and started winging it based on personal friendship. If this were a small commercial crew, sure, fine, but Rake has a personal command responsibility that she obsessively angsts about and yet keeps abandoning. I realize this is probably another way to complain that I wanted competence porn and got barely-functional fuck-ups. The best parts of this series are the strange technologies and the aliens, and they are again the best part of this book. There was a truly great moment involving Viator technology that I found utterly delightful, and there was an intriguing setup for future books that caught my attention. Unfortunately, there were also a lot of deus ex machina solutions to problems, both from convenient undisclosed character backstories and from alien tech. I felt like the characters had to work satisfyingly hard for their victories in the first book; here, I felt like Dewes kept having issues with her characters being at point A and her plot at point B and pulling some rabbit out of the hat to make the plot work. This unfortunately undermined the cool factor of the world-building by making its plot device aspects a bit too obvious. This series also turns out not to be a duology (I have no idea why I thought it would be). By the end of The Exiled Fleet, none of the major political or world-building problems have been resolved. At best, the characters are in a more stable space to start being proactive. I'm cautiously optimistic that could mean the series would turn into the type of story I was hoping for, but I'm worried that Dewes is interested in writing a different type of character story than I am interested in reading. Hopefully there will be some clues in the synopsis of the (as yet unannounced) third book. I thought The Last Watch had some first-novel problems but was worth reading. I am much more reluctant to recommend The Exiled Fleet, or the series as a whole given that it is incomplete. Unless you like dysfunctional characters, proceed with caution. Rating: 5 out of 10

17 November 2023

Jonathan Dowland: HLedger, regex matches and field assignments

I've finally landed a patch/feature for HLedger I've been working on-and-off (mostly off) since around March. HLedger has a powerful CSV importer which you configure with a set of rules. Rules consist of conditional matchers (does field X in this CSV row match this regular expression?) and field assignments (set the resulting transaction's account to Y). motivating problem 1 Here's an example of one of my rules for handling credit card repayments. This rule is applied when I import a CSV for my current account, which pays the credit card:
if AMERICAN EXPRESS
    account2 liabilities:amex
This results in a ledger entry like the following
2023-10-31 AMERICAN EXPRESS
    assets:current           - 6.66
    liabilities:amex           6.66
My current account statements cover calendar months. My credit card period spans mid-month to mid-month. I pay it off by direct debit, which comes out after the credit card period, towards the very end of the calendar month. That transaction falls roughly halfway through the next credit card period. On my credit card statements, that repayment is "warped" to the start of the list of transactions, clearing the outstanding balance from the previous period. When I import my credit card data to HLedger, I want to compare the result against a PDF statement to make sure my ledger matches reality. The repayment "warping" makes this awkward, because it means the balance for roughly half the new transactions (those that fall before the real-date of the repayment) don't match up. motivating problem 2 I start new ledger files each year. I need to import the closing balances from the previous year to the next, which I do by exporting the final balance from the previous year in CSV and importing that into the new ledgers in the usual way. Between 2022 and 2023 I changed the scheme I use for account names so I need to translate between the old and the new in the opening balances. I couldn't think of a way of achieving this in the import rules (besides writing a bespoke rule for every possible old account name) so I abused another HLedger feature instead, HLedger aliases. For example I added this alias in my family ledger file for 2023
alias /^family:(.*)/ = \1
These are ugly and I'd prefer to get rid of them. regex match groups A common feature of regular expressions is defining match groups which can be referenced elsewhere, such as on the far-side of a substitution. I added match group support to HLedger's field assignments. addressing date warping Here's an updated version rule from the first motivating problem:
if AMERICAN EXPRESS
& %date (..)/(..)/(....)
    account2 liabilities:amex
    comment2 date:\3-\2-16
We now match on on extra date field, and surround the day/month/year components with parentheses to define match groups. We add a second field assignment too, setting the second posting's "comment" field to a string which, once the match groups are interpolated, instructs HLedger to do date warping (I wrote about this in date warping in HLedger) The new transaction looks like this:
2023-10-31 AMERICAN EXPRESS
    assets:current           - 6.66
    liabilities:amex           6.66 ; date:2023-10-16
getting rid of aliases In the second problem, I can strip off the unwanted account name prefixes at CSV import time, with rules like this
if %account2 ^family:(.*)$
    account2 \1
When! This stuff landed a week ago in early November, and is not yet in a Hledger release.

16 November 2023

Dimitri John Ledkov: Ubuntu 23.10 significantly reduces the installed kernel footprint


Photo by Pixabay
Ubuntu systems typically have up to 3 kernels installed, before they are auto-removed by apt on classic installs. Historically the installation was optimized for metered download size only. However, kernel size growth and usage no longer warrant such optimizations. During the 23.10 Mantic Minatour cycle, I led a coordinated effort across multiple teams to implement lots of optimizations that together achieved unprecedented install footprint improvements.

Given a typical install of 3 generic kernel ABIs in the default configuration on a regular-sized VM (2 CPU cores 8GB of RAM) the following metrics are achieved in Ubuntu 23.10 versus Ubuntu 22.04 LTS:

  • 2x less disk space used (1,417MB vs 2,940MB, including initrd)

  • 3x less peak RAM usage for the initrd boot (68MB vs 204MB)

  • 0.5x increase in download size (949MB vs 600MB)

  • 2.5x faster initrd generation (4.5s vs 11.3s)

  • approximately the same total time (103s vs 98s, hardware dependent)


For minimal cloud images that do not install either linux-firmware or modules extra the numbers are:

  • 1.3x less disk space used (548MB vs 742MB)

  • 2.2x less peak RAM usage for initrd boot (27MB vs 62MB)

  • 0.4x increase in download size (207MB vs 146MB)


Hopefully, the compromise of download size, relative to the disk space & initrd savings is a win for the majority of platforms and use cases. For users on extremely expensive and metered connections, the likely best saving is to receive air-gapped updates or skip updates.

This was achieved by precompressing kernel modules & firmware files with the maximum level of Zstd compression at package build time; making actual .deb files uncompressed; assembling the initrd using split cpio archives - uncompressed for the pre-compressed files, whilst compressing only the userspace portions of the initrd; enabling in-kernel module decompression support with matching kmod; fixing bugs in all of the above, and landing all of these things in time for the feature freeze. Whilst leveraging the experience and some of the design choices implementations we have already been shipping on Ubuntu Core. Some of these changes are backported to Jammy, but only enough to support smooth upgrades to Mantic and later. Complete gains are only possible to experience on Mantic and later.

The discovered bugs in kernel module loading code likely affect systems that use LoadPin LSM with kernel space module uncompression as used on ChromeOS systems. Hopefully, Kees Cook or other ChromeOS developers pick up the kernel fixes from the stable trees. Or you know, just use Ubuntu kernels as they do get fixes and features like these first.

The team that designed and delivered these changes is large: Benjamin Drung, Andrea Righi, Juerg Haefliger, Julian Andres Klode, Steve Langasek, Michael Hudson-Doyle, Robert Kratky, Adrien Nader, Tim Gardner, Roxana Nicolescu - and myself Dimitri John Ledkov ensuring the most optimal solution is implemented, everything lands on time, and even implementing portions of the final solution.

Hi, It's me, I am a Staff Engineer at Canonical and we are hiring https://canonical.com/careers.

Lots of additional technical details and benchmarks on a huge range of diverse hardware and architectures, and bikeshedding all the things below:

For questions and comments please post to Kernel section on Ubuntu Discourse.



12 November 2023

Petter Reinholdtsen: New and improved sqlcipher in Debian for accessing Signal database

For a while now I wanted to have direct access to the Signal database of messages and channels of my Desktop edition of Signal. I prefer the enforced end to end encryption of Signal these days for my communication with friends and family, to increase the level of safety and privacy as well as raising the cost of the mass surveillance government and non-government entities practice these days. In August I came across a nice recipe on how to use sqlcipher to extract statistics from the Signal database explaining how to do this. Unfortunately this did not work with the version of sqlcipher in Debian. The sqlcipher package is a "fork" of the sqlite package with added support for encrypted databases. Sadly the current Debian maintainer announced more than three years ago that he did not have time to maintain sqlcipher, so it seemed unlikely to be upgraded by the maintainer. I was reluctant to take on the job myself, as I have very limited experience maintaining shared libraries in Debian. After waiting and hoping for a few months, I gave up the last week, and set out to update the package. In the process I orphaned it to make it more obvious for the next person looking at it that the package need proper maintenance. The version in Debian was around five years old, and quite a lot of changes had taken place upstream into the Debian maintenance git repository. After spending a few days importing the new upstream versions, realising that upstream did not care much for SONAME versioning as I saw library symbols being both added and removed with minor version number changes to the project, I concluded that I had to do a SONAME bump of the library package to avoid surprising the reverse dependencies. I even added a simple autopkgtest script to ensure the package work as intended. Dug deep into the hole of learning shared library maintenance, I set out a few days ago to upload the new version to Debian experimental to see what the quality assurance framework in Debian had to say about the result. The feedback told me the pacakge was not too shabby, and yesterday I uploaded the latest version to Debian unstable. It should enter testing today or tomorrow, perhaps delayed by a small library transition. Armed with a new version of sqlcipher, I can now have a look at the SQL database in ~/.config/Signal/sql/db.sqlite. First, one need to fetch the encryption key from the Signal configuration using this simple JSON extraction command:
/usr/bin/jq -r '."key"' ~/.config/Signal/config.json
Assuming the result from that command is 'secretkey', which is a hexadecimal number representing the key used to encrypt the database. Next, one can now connect to the database and inject the encryption key for access via SQL to fetch information from the database. Here is an example dumping the database structure:
% sqlcipher ~/.config/Signal/sql/db.sqlite
sqlite> PRAGMA key = "x'secretkey'";
sqlite> .schema
CREATE TABLE sqlite_stat1(tbl,idx,stat);
CREATE TABLE conversations(
      id STRING PRIMARY KEY ASC,
      json TEXT,
      active_at INTEGER,
      type STRING,
      members TEXT,
      name TEXT,
      profileName TEXT
    , profileFamilyName TEXT, profileFullName TEXT, e164 TEXT, serviceId TEXT, groupId TEXT, profileLastFetchedAt INTEGER);
CREATE TABLE identityKeys(
      id STRING PRIMARY KEY ASC,
      json TEXT
    );
CREATE TABLE items(
      id STRING PRIMARY KEY ASC,
      json TEXT
    );
CREATE TABLE sessions(
      id TEXT PRIMARY KEY,
      conversationId TEXT,
      json TEXT
    , ourServiceId STRING, serviceId STRING);
CREATE TABLE attachment_downloads(
    id STRING primary key,
    timestamp INTEGER,
    pending INTEGER,
    json TEXT
  );
CREATE TABLE sticker_packs(
    id TEXT PRIMARY KEY,
    key TEXT NOT NULL,
    author STRING,
    coverStickerId INTEGER,
    createdAt INTEGER,
    downloadAttempts INTEGER,
    installedAt INTEGER,
    lastUsed INTEGER,
    status STRING,
    stickerCount INTEGER,
    title STRING
  , attemptedStatus STRING, position INTEGER DEFAULT 0 NOT NULL, storageID STRING, storageVersion INTEGER, storageUnknownFields BLOB, storageNeedsSync
      INTEGER DEFAULT 0 NOT NULL);
CREATE TABLE stickers(
    id INTEGER NOT NULL,
    packId TEXT NOT NULL,
    emoji STRING,
    height INTEGER,
    isCoverOnly INTEGER,
    lastUsed INTEGER,
    path STRING,
    width INTEGER,
    PRIMARY KEY (id, packId),
    CONSTRAINT stickers_fk
      FOREIGN KEY (packId)
      REFERENCES sticker_packs(id)
      ON DELETE CASCADE
  );
CREATE TABLE sticker_references(
    messageId STRING,
    packId TEXT,
    CONSTRAINT sticker_references_fk
      FOREIGN KEY(packId)
      REFERENCES sticker_packs(id)
      ON DELETE CASCADE
  );
CREATE TABLE emojis(
    shortName TEXT PRIMARY KEY,
    lastUsage INTEGER
  );
CREATE TABLE messages(
        rowid INTEGER PRIMARY KEY ASC,
        id STRING UNIQUE,
        json TEXT,
        readStatus INTEGER,
        expires_at INTEGER,
        sent_at INTEGER,
        schemaVersion INTEGER,
        conversationId STRING,
        received_at INTEGER,
        source STRING,
        hasAttachments INTEGER,
        hasFileAttachments INTEGER,
        hasVisualMediaAttachments INTEGER,
        expireTimer INTEGER,
        expirationStartTimestamp INTEGER,
        type STRING,
        body TEXT,
        messageTimer INTEGER,
        messageTimerStart INTEGER,
        messageTimerExpiresAt INTEGER,
        isErased INTEGER,
        isViewOnce INTEGER,
        sourceServiceId TEXT, serverGuid STRING NULL, sourceDevice INTEGER, storyId STRING, isStory INTEGER
        GENERATED ALWAYS AS (type IS 'story'), isChangeCreatedByUs INTEGER NOT NULL DEFAULT 0, isTimerChangeFromSync INTEGER
        GENERATED ALWAYS AS (
          json_extract(json, '$.expirationTimerUpdate.fromSync') IS 1
        ), seenStatus NUMBER default 0, storyDistributionListId STRING, expiresAt INT
        GENERATED ALWAYS
        AS (ifnull(
          expirationStartTimestamp + (expireTimer * 1000),
          9007199254740991
        )), shouldAffectActivity INTEGER
        GENERATED ALWAYS AS (
          type IS NULL
          OR
          type NOT IN (
            'change-number-notification',
            'contact-removed-notification',
            'conversation-merge',
            'group-v1-migration',
            'keychange',
            'message-history-unsynced',
            'profile-change',
            'story',
            'universal-timer-notification',
            'verified-change'
          )
        ), shouldAffectPreview INTEGER
        GENERATED ALWAYS AS (
          type IS NULL
          OR
          type NOT IN (
            'change-number-notification',
            'contact-removed-notification',
            'conversation-merge',
            'group-v1-migration',
            'keychange',
            'message-history-unsynced',
            'profile-change',
            'story',
            'universal-timer-notification',
            'verified-change'
          )
        ), isUserInitiatedMessage INTEGER
        GENERATED ALWAYS AS (
          type IS NULL
          OR
          type NOT IN (
            'change-number-notification',
            'contact-removed-notification',
            'conversation-merge',
            'group-v1-migration',
            'group-v2-change',
            'keychange',
            'message-history-unsynced',
            'profile-change',
            'story',
            'universal-timer-notification',
            'verified-change'
          )
        ), mentionsMe INTEGER NOT NULL DEFAULT 0, isGroupLeaveEvent INTEGER
        GENERATED ALWAYS AS (
          type IS 'group-v2-change' AND
          json_array_length(json_extract(json, '$.groupV2Change.details')) IS 1 AND
          json_extract(json, '$.groupV2Change.details[0].type') IS 'member-remove' AND
          json_extract(json, '$.groupV2Change.from') IS NOT NULL AND
          json_extract(json, '$.groupV2Change.from') IS json_extract(json, '$.groupV2Change.details[0].aci')
        ), isGroupLeaveEventFromOther INTEGER
        GENERATED ALWAYS AS (
          isGroupLeaveEvent IS 1
          AND
          isChangeCreatedByUs IS 0
        ), callId TEXT
        GENERATED ALWAYS AS (
          json_extract(json, '$.callId')
        ));
CREATE TABLE sqlite_stat4(tbl,idx,neq,nlt,ndlt,sample);
CREATE TABLE jobs(
        id TEXT PRIMARY KEY,
        queueType TEXT STRING NOT NULL,
        timestamp INTEGER NOT NULL,
        data STRING TEXT
      );
CREATE TABLE reactions(
        conversationId STRING,
        emoji STRING,
        fromId STRING,
        messageReceivedAt INTEGER,
        targetAuthorAci STRING,
        targetTimestamp INTEGER,
        unread INTEGER
      , messageId STRING);
CREATE TABLE senderKeys(
        id TEXT PRIMARY KEY NOT NULL,
        senderId TEXT NOT NULL,
        distributionId TEXT NOT NULL,
        data BLOB NOT NULL,
        lastUpdatedDate NUMBER NOT NULL
      );
CREATE TABLE unprocessed(
        id STRING PRIMARY KEY ASC,
        timestamp INTEGER,
        version INTEGER,
        attempts INTEGER,
        envelope TEXT,
        decrypted TEXT,
        source TEXT,
        serverTimestamp INTEGER,
        sourceServiceId STRING
      , serverGuid STRING NULL, sourceDevice INTEGER, receivedAtCounter INTEGER, urgent INTEGER, story INTEGER);
CREATE TABLE sendLogPayloads(
        id INTEGER PRIMARY KEY ASC,
        timestamp INTEGER NOT NULL,
        contentHint INTEGER NOT NULL,
        proto BLOB NOT NULL
      , urgent INTEGER, hasPniSignatureMessage INTEGER DEFAULT 0 NOT NULL);
CREATE TABLE sendLogRecipients(
        payloadId INTEGER NOT NULL,
        recipientServiceId STRING NOT NULL,
        deviceId INTEGER NOT NULL,
        PRIMARY KEY (payloadId, recipientServiceId, deviceId),
        CONSTRAINT sendLogRecipientsForeignKey
          FOREIGN KEY (payloadId)
          REFERENCES sendLogPayloads(id)
          ON DELETE CASCADE
      );
CREATE TABLE sendLogMessageIds(
        payloadId INTEGER NOT NULL,
        messageId STRING NOT NULL,
        PRIMARY KEY (payloadId, messageId),
        CONSTRAINT sendLogMessageIdsForeignKey
          FOREIGN KEY (payloadId)
          REFERENCES sendLogPayloads(id)
          ON DELETE CASCADE
      );
CREATE TABLE preKeys(
        id STRING PRIMARY KEY ASC,
        json TEXT
      , ourServiceId NUMBER
        GENERATED ALWAYS AS (json_extract(json, '$.ourServiceId')));
CREATE TABLE signedPreKeys(
        id STRING PRIMARY KEY ASC,
        json TEXT
      , ourServiceId NUMBER
        GENERATED ALWAYS AS (json_extract(json, '$.ourServiceId')));
CREATE TABLE badges(
        id TEXT PRIMARY KEY,
        category TEXT NOT NULL,
        name TEXT NOT NULL,
        descriptionTemplate TEXT NOT NULL
      );
CREATE TABLE badgeImageFiles(
        badgeId TEXT REFERENCES badges(id)
          ON DELETE CASCADE
          ON UPDATE CASCADE,
        'order' INTEGER NOT NULL,
        url TEXT NOT NULL,
        localPath TEXT,
        theme TEXT NOT NULL
      );
CREATE TABLE storyReads (
        authorId STRING NOT NULL,
        conversationId STRING NOT NULL,
        storyId STRING NOT NULL,
        storyReadDate NUMBER NOT NULL,
        PRIMARY KEY (authorId, storyId)
      );
CREATE TABLE storyDistributions(
        id STRING PRIMARY KEY NOT NULL,
        name TEXT,
        senderKeyInfoJson STRING
      , deletedAtTimestamp INTEGER, allowsReplies INTEGER, isBlockList INTEGER, storageID STRING, storageVersion INTEGER, storageUnknownFields BLOB, storageNeedsSync INTEGER);
CREATE TABLE storyDistributionMembers(
        listId STRING NOT NULL REFERENCES storyDistributions(id)
          ON DELETE CASCADE
          ON UPDATE CASCADE,
        serviceId STRING NOT NULL,
        PRIMARY KEY (listId, serviceId)
      );
CREATE TABLE uninstalled_sticker_packs (
        id STRING NOT NULL PRIMARY KEY,
        uninstalledAt NUMBER NOT NULL,
        storageID STRING,
        storageVersion NUMBER,
        storageUnknownFields BLOB,
        storageNeedsSync INTEGER NOT NULL
      );
CREATE TABLE groupCallRingCancellations(
        ringId INTEGER PRIMARY KEY,
        createdAt INTEGER NOT NULL
      );
CREATE TABLE IF NOT EXISTS 'messages_fts_data'(id INTEGER PRIMARY KEY, block BLOB);
CREATE TABLE IF NOT EXISTS 'messages_fts_idx'(segid, term, pgno, PRIMARY KEY(segid, term)) WITHOUT ROWID;
CREATE TABLE IF NOT EXISTS 'messages_fts_content'(id INTEGER PRIMARY KEY, c0);
CREATE TABLE IF NOT EXISTS 'messages_fts_docsize'(id INTEGER PRIMARY KEY, sz BLOB);
CREATE TABLE IF NOT EXISTS 'messages_fts_config'(k PRIMARY KEY, v) WITHOUT ROWID;
CREATE TABLE edited_messages(
        messageId STRING REFERENCES messages(id)
          ON DELETE CASCADE,
        sentAt INTEGER,
        readStatus INTEGER
      , conversationId STRING);
CREATE TABLE mentions (
        messageId REFERENCES messages(id) ON DELETE CASCADE,
        mentionAci STRING,
        start INTEGER,
        length INTEGER
      );
CREATE TABLE kyberPreKeys(
        id STRING PRIMARY KEY NOT NULL,
        json TEXT NOT NULL, ourServiceId NUMBER
        GENERATED ALWAYS AS (json_extract(json, '$.ourServiceId')));
CREATE TABLE callsHistory (
        callId TEXT PRIMARY KEY,
        peerId TEXT NOT NULL, -- conversation id (legacy)   uuid   groupId   roomId
        ringerId TEXT DEFAULT NULL, -- ringer uuid
        mode TEXT NOT NULL, -- enum "Direct"   "Group"
        type TEXT NOT NULL, -- enum "Audio"   "Video"   "Group"
        direction TEXT NOT NULL, -- enum "Incoming"   "Outgoing
        -- Direct: enum "Pending"   "Missed"   "Accepted"   "Deleted"
        -- Group: enum "GenericGroupCall"   "OutgoingRing"   "Ringing"   "Joined"   "Missed"   "Declined"   "Accepted"   "Deleted"
        status TEXT NOT NULL,
        timestamp INTEGER NOT NULL,
        UNIQUE (callId, peerId) ON CONFLICT FAIL
      );
[ dropped all indexes to save space in this blog post ]
CREATE TRIGGER messages_on_view_once_update AFTER UPDATE ON messages
      WHEN
        new.body IS NOT NULL AND new.isViewOnce = 1
      BEGIN
        DELETE FROM messages_fts WHERE rowid = old.rowid;
      END;
CREATE TRIGGER messages_on_insert AFTER INSERT ON messages
      WHEN new.isViewOnce IS NOT 1 AND new.storyId IS NULL
      BEGIN
        INSERT INTO messages_fts
          (rowid, body)
        VALUES
          (new.rowid, new.body);
      END;
CREATE TRIGGER messages_on_delete AFTER DELETE ON messages BEGIN
        DELETE FROM messages_fts WHERE rowid = old.rowid;
        DELETE FROM sendLogPayloads WHERE id IN (
          SELECT payloadId FROM sendLogMessageIds
          WHERE messageId = old.id
        );
        DELETE FROM reactions WHERE rowid IN (
          SELECT rowid FROM reactions
          WHERE messageId = old.id
        );
        DELETE FROM storyReads WHERE storyId = old.storyId;
      END;
CREATE VIRTUAL TABLE messages_fts USING fts5(
        body,
        tokenize = 'signal_tokenizer'
      );
CREATE TRIGGER messages_on_update AFTER UPDATE ON messages
      WHEN
        (new.body IS NULL OR old.body IS NOT new.body) AND
         new.isViewOnce IS NOT 1 AND new.storyId IS NULL
      BEGIN
        DELETE FROM messages_fts WHERE rowid = old.rowid;
        INSERT INTO messages_fts
          (rowid, body)
        VALUES
          (new.rowid, new.body);
      END;
CREATE TRIGGER messages_on_insert_insert_mentions AFTER INSERT ON messages
      BEGIN
        INSERT INTO mentions (messageId, mentionAci, start, length)
        
    SELECT messages.id, bodyRanges.value ->> 'mentionAci' as mentionAci,
      bodyRanges.value ->> 'start' as start,
      bodyRanges.value ->> 'length' as length
    FROM messages, json_each(messages.json ->> 'bodyRanges') as bodyRanges
    WHERE bodyRanges.value ->> 'mentionAci' IS NOT NULL
  
        AND messages.id = new.id;
      END;
CREATE TRIGGER messages_on_update_update_mentions AFTER UPDATE ON messages
      BEGIN
        DELETE FROM mentions WHERE messageId = new.id;
        INSERT INTO mentions (messageId, mentionAci, start, length)
        
    SELECT messages.id, bodyRanges.value ->> 'mentionAci' as mentionAci,
      bodyRanges.value ->> 'start' as start,
      bodyRanges.value ->> 'length' as length
    FROM messages, json_each(messages.json ->> 'bodyRanges') as bodyRanges
    WHERE bodyRanges.value ->> 'mentionAci' IS NOT NULL
  
        AND messages.id = new.id;
      END;
sqlite>
Finally I have the tool needed to inspect and process Signal messages that I need, without using the vendor provided client. Now on to transforming it to a more useful format. As usual, if you use Bitcoin and want to show your support of my activities, please send Bitcoin donations to my address 15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

7 November 2023

Melissa Wen: AMD Driver-specific Properties for Color Management on Linux (Part 2)

TL;DR: This blog post explores the color capabilities of AMD hardware and how they are exposed to userspace through driver-specific properties. It discusses the different color blocks in the AMD Display Core Next (DCN) pipeline and their capabilities, such as predefined transfer functions, 1D and 3D lookup tables (LUTs), and color transformation matrices (CTMs). It also highlights the differences in AMD HW blocks for pre and post-blending adjustments, and how these differences are reflected in the available driver-specific properties. Overall, this blog post provides a comprehensive overview of the color capabilities of AMD hardware and how they can be controlled by userspace applications through driver-specific properties. This information is valuable for anyone who wants to develop applications that can take advantage of the AMD color management pipeline. Get a closer look at each hardware block s capabilities, unlock a wealth of knowledge about AMD display hardware, and enhance your understanding of graphics and visual computing. Stay tuned for future developments as we embark on a quest for GPU color capabilities in the ever-evolving realm of rainbow treasures.
Operating Systems can use the power of GPUs to ensure consistent color reproduction across graphics devices. We can use GPU-accelerated color management to manage the diversity of color profiles, do color transformations to convert between High-Dynamic-Range (HDR) and Standard-Dynamic-Range (SDR) content and color enhacements for wide color gamut (WCG). However, to make use of GPU display capabilities, we need an interface between userspace and the kernel display drivers that is currently absent in the Linux/DRM KMS API. In the previous blog post I presented how we are expanding the Linux/DRM color management API to expose specific properties of AMD hardware. Now, I ll guide you to the color features for the Linux/AMD display driver. We embark on a journey through DRM/KMS, AMD Display Manager, and AMD Display Core and delve into the color blocks to uncover the secrets of color manipulation within AMD hardware. Here we ll talk less about the color tools and more about where to find them in the hardware. We resort to driver-specific properties to reach AMD hardware blocks with color capabilities. These blocks display features like predefined transfer functions, color transformation matrices, and 1-dimensional (1D LUT) and 3-dimensional lookup tables (3D LUT). Here, we will understand how these color features are strategically placed into color blocks both before and after blending in Display Pipe and Plane (DPP) and Multiple Pipe/Plane Combined (MPC) blocks. That said, welcome back to the second part of our thrilling journey through AMD s color management realm!

AMD Display Driver in the Linux/DRM Subsystem: The Journey In my 2022 XDC talk I m not an AMD expert, but , I briefly explained the organizational structure of the Linux/AMD display driver where the driver code is bifurcated into a Linux-specific section and a shared-code portion. To reveal AMD s color secrets through the Linux kernel DRM API, our journey led us through these layers of the Linux/AMD display driver s software stack. It includes traversing the DRM/KMS framework, the AMD Display Manager (DM), and the AMD Display Core (DC) [1]. The DRM/KMS framework provides the atomic API for color management through KMS properties represented by struct drm_property. We extended the color management interface exposed to userspace by leveraging existing resources and connecting them with driver-specific functions for managing modeset properties. On the AMD DC layer, the interface with hardware color blocks is established. The AMD DC layer contains OS-agnostic components that are shared across different platforms, making it an invaluable resource. This layer already implements hardware programming and resource management, simplifying the external developer s task. While examining the DC code, we gain insights into the color pipeline and capabilities, even without direct access to specifications. Additionally, AMD developers provide essential support by answering queries and reviewing our work upstream. The primary challenge involved identifying and understanding relevant AMD DC code to configure each color block in the color pipeline. However, the ultimate goal was to bridge the DC color capabilities with the DRM API. For this, we changed the AMD DM, the OS-dependent layer connecting the DC interface to the DRM/KMS framework. We defined and managed driver-specific color properties, facilitated the transport of user space data to the DC, and translated DRM features and settings to the DC interface. Considerations were also made for differences in the color pipeline based on hardware capabilities.

Exploring Color Capabilities of the AMD display hardware Now, let s dive into the exciting realm of AMD color capabilities, where a abundance of techniques and tools await to make your colors look extraordinary across diverse devices. First, we need to know a little about the color transformation and calibration tools and techniques that you can find in different blocks of the AMD hardware. I borrowed some images from [2] [3] [4] to help you understand the information.

Predefined Transfer Functions (Named Fixed Curves): Transfer functions serve as the bridge between the digital and visual worlds, defining the mathematical relationship between digital color values and linear scene/display values and ensuring consistent color reproduction across different devices and media. You can learn more about curves in the chapter GPU Gems 3 - The Importance of Being Linear by Larry Gritz and Eugene d Eon. ITU-R 2100 introduces three main types of transfer functions:
  • OETF: the opto-electronic transfer function, which converts linear scene light into the video signal, typically within a camera.
  • EOTF: electro-optical transfer function, which converts the video signal into the linear light output of the display.
  • OOTF: opto-optical transfer function, which has the role of applying the rendering intent .
AMD s display driver supports the following pre-defined transfer functions (aka named fixed curves):
  • Linear/Unity: linear/identity relationship between pixel value and luminance value;
  • Gamma 2.2, Gamma 2.4, Gamma 2.6: pure power functions;
  • sRGB: 2.4: The piece-wise transfer function from IEC 61966-2-1:1999;
  • BT.709: has a linear segment in the bottom part and then a power function with a 0.45 (~1/2.22) gamma for the rest of the range; standardized by ITU-R BT.709-6;
  • PQ (Perceptual Quantizer): used for HDR display, allows luminance range capability of 0 to 10,000 nits; standardized by SMPTE ST 2084.
These capabilities vary depending on the hardware block, with some utilizing hardcoded curves and others relying on AMD s color module to construct curves from standardized coefficients. It also supports user/custom curves built from a lookup table.

1D LUTs (1-dimensional Lookup Table): A 1D LUT is a versatile tool, defining a one-dimensional color transformation based on a single parameter. It s very well explained by Jeremy Selan at GPU Gems 2 - Chapter 24 Using Lookup Tables to Accelerate Color Transformations It enables adjustments to color, brightness, and contrast, making it ideal for fine-tuning. In the Linux AMD display driver, the atomic API offers a 1D LUT with 4096 entries and 8-bit depth, while legacy gamma uses a size of 256.

3D LUTs (3-dimensional Lookup Table): These tables work in three dimensions red, green, and blue. They re perfect for complex color transformations and adjustments between color channels. It s also more complex to manage and require more computational resources. Jeremy also explains 3D LUT at GPU Gems 2 - Chapter 24 Using Lookup Tables to Accelerate Color Transformations

CTM (Color Transformation Matrices): Color transformation matrices facilitate the transition between different color spaces, playing a crucial role in color space conversion.

HDR Multiplier: HDR multiplier is a factor applied to the color values of an image to increase their overall brightness.

AMD Color Capabilities in the Hardware Pipeline First, let s take a closer look at the AMD Display Core Next hardware pipeline in the Linux kernel documentation for AMDGPU driver - Display Core Next In the AMD Display Core Next hardware pipeline, we encounter two hardware blocks with color capabilities: the Display Pipe and Plane (DPP) and the Multiple Pipe/Plane Combined (MPC). The DPP handles color adjustments per plane before blending, while the MPC engages in post-blending color adjustments. In short, we expect DPP color capabilities to match up with DRM plane properties, and MPC color capabilities to play nice with DRM CRTC properties. Note: here s the catch there are some DRM CRTC color transformations that don t have a corresponding AMD MPC color block, and vice versa. It s like a puzzle, and we re here to solve it!

AMD Color Blocks and Capabilities We can finally talk about the color capabilities of each AMD color block. As it varies based on the generation of hardware, let s take the DCN3+ family as reference. What s possible to do before and after blending depends on hardware capabilities describe in the kernel driver by struct dpp_color_caps and struct mpc_color_caps. The AMD Steam Deck hardware provides a tangible example of these capabilities. Therefore, we take SteamDeck/DCN301 driver as an example and look at the Color pipeline capabilities described in the file: driver/gpu/drm/amd/display/dcn301/dcn301_resources.c
/* Color pipeline capabilities */
dc->caps.color.dpp.dcn_arch = 1; // If it is a Display Core Next (DCN): yes. Zero means DCE.
dc->caps.color.dpp.input_lut_shared = 0;
dc->caps.color.dpp.icsc = 1; // Intput Color Space Conversion  (CSC) matrix.
dc->caps.color.dpp.dgam_ram = 0; // The old degamma block for degamma curve (hardcoded and LUT).  Gamma correction  is the new one.
dc->caps.color.dpp.dgam_rom_caps.srgb = 1; // sRGB hardcoded curve support
dc->caps.color.dpp.dgam_rom_caps.bt2020 = 1; // BT2020 hardcoded curve support (seems not actually in use)
dc->caps.color.dpp.dgam_rom_caps.gamma2_2 = 1; // Gamma 2.2 hardcoded curve support
dc->caps.color.dpp.dgam_rom_caps.pq = 1; // PQ hardcoded curve support
dc->caps.color.dpp.dgam_rom_caps.hlg = 1; // HLG hardcoded curve support
dc->caps.color.dpp.post_csc = 1; // CSC matrix
dc->caps.color.dpp.gamma_corr = 1; // New  Gamma Correction  block for degamma user LUT;
dc->caps.color.dpp.dgam_rom_for_yuv = 0;
dc->caps.color.dpp.hw_3d_lut = 1; // 3D LUT support. If so, it's always preceded by a shaper curve. 
dc->caps.color.dpp.ogam_ram = 1; //  Blend Gamma  block for custom curve just after blending
// no OGAM ROM on DCN301
dc->caps.color.dpp.ogam_rom_caps.srgb = 0;
dc->caps.color.dpp.ogam_rom_caps.bt2020 = 0;
dc->caps.color.dpp.ogam_rom_caps.gamma2_2 = 0;
dc->caps.color.dpp.ogam_rom_caps.pq = 0;
dc->caps.color.dpp.ogam_rom_caps.hlg = 0;
dc->caps.color.dpp.ocsc = 0;
dc->caps.color.mpc.gamut_remap = 1; // Post-blending CTM (pre-blending CTM is always supported)
dc->caps.color.mpc.num_3dluts = pool->base.res_cap->num_mpc_3dlut; // Post-blending 3D LUT (preceded by shaper curve)
dc->caps.color.mpc.ogam_ram = 1; // Post-blending regamma.
// No pre-defined TF supported for regamma.
dc->caps.color.mpc.ogam_rom_caps.srgb = 0;
dc->caps.color.mpc.ogam_rom_caps.bt2020 = 0;
dc->caps.color.mpc.ogam_rom_caps.gamma2_2 = 0;
dc->caps.color.mpc.ogam_rom_caps.pq = 0;
dc->caps.color.mpc.ogam_rom_caps.hlg = 0;
dc->caps.color.mpc.ocsc = 1; // Output CSC matrix.
I included some inline comments in each element of the color caps to quickly describe them, but you can find the same information in the Linux kernel documentation. See more in struct dpp_color_caps, struct mpc_color_caps and struct rom_curve_caps. Now, using this guideline, we go through color capabilities of DPP and MPC blocks and talk more about mapping driver-specific properties to corresponding color blocks.

DPP Color Pipeline: Before Blending (Per Plane) Let s explore the capabilities of DPP blocks and what you can achieve with a color block. The very first thing to pay attention is the display architecture of the display hardware: previously AMD uses a display architecture called DCE
  • Display and Compositing Engine, but newer hardware follows DCN - Display Core Next.
The architectute is described by: dc->caps.color.dpp.dcn_arch

AMD Plane Degamma: TF and 1D LUT Described by: dc->caps.color.dpp.dgam_ram, dc->caps.color.dpp.dgam_rom_caps,dc->caps.color.dpp.gamma_corr AMD Plane Degamma data is mapped to the initial stage of the DPP pipeline. It is utilized to transition from scanout/encoded values to linear values for arithmetic operations. Plane Degamma supports both pre-defined transfer functions and 1D LUTs, depending on the hardware generation. DCN2 and older families handle both types of curve in the Degamma RAM block (dc->caps.color.dpp.dgam_ram); DCN3+ separate hardcoded curves and 1D LUT into two block: Degamma ROM (dc->caps.color.dpp.dgam_rom_caps) and Gamma correction block (dc->caps.color.dpp.gamma_corr), respectively. Pre-defined transfer functions:
  • they are hardcoded curves (read-only memory - ROM);
  • supported curves: sRGB EOTF, BT.709 inverse OETF, PQ EOTF and HLG OETF, Gamma 2.2, Gamma 2.4 and Gamma 2.6 EOTF.
The 1D LUT currently accepts 4096 entries of 8-bit. The data is interpreted as an array of struct drm_color_lut elements. Setting TF = Identity/Default and LUT as NULL means bypass. References:

AMD Plane 3x4 CTM (Color Transformation Matrix) AMD Plane CTM data goes to the DPP Gamut Remap block, supporting a 3x4 fixed point (s31.32) matrix for color space conversions. The data is interpreted as a struct drm_color_ctm_3x4. Setting NULL means bypass. References:

AMD Plane Shaper: TF + 1D LUT Described by: dc->caps.color.dpp.hw_3d_lut The Shaper block fine-tunes color adjustments before applying the 3D LUT, optimizing the use of the limited entries in each dimension of the 3D LUT. On AMD hardware, a 3D LUT always means a preceding shaper 1D LUT used for delinearizing and/or normalizing the color space before applying a 3D LUT, so this entry on DPP color caps dc->caps.color.dpp.hw_3d_lut means support for both shaper 1D LUT and 3D LUT. Pre-defined transfer function enables delinearizing content with or without shaper LUT, where AMD color module calculates the resulted shaper curve. Shaper curves go from linear values to encoded values. If we are already in a non-linear space and/or don t need to normalize values, we can set a Identity TF for shaper that works similar to bypass and is also the default TF value. Pre-defined transfer functions:
  • there is no DPP Shaper ROM. Curves are calculated by AMD color modules. Check calculate_curve() function in the file amd/display/modules/color/color_gamma.c.
  • supported curves: Identity, sRGB inverse EOTF, BT.709 OETF, PQ inverse EOTF, HLG OETF, and Gamma 2.2, Gamma 2.4, Gamma 2.6 inverse EOTF.
The 1D LUT currently accepts 4096 entries of 8-bit. The data is interpreted as an array of struct drm_color_lut elements. When setting Plane Shaper TF (!= Identity) and LUT at the same time, the color module will combine the pre-defined TF and the custom LUT values into the LUT that s actually programmed. Setting TF = Identity/Default and LUT as NULL works as bypass. References:

AMD Plane 3D LUT Described by: dc->caps.color.dpp.hw_3d_lut The 3D LUT in the DPP block facilitates complex color transformations and adjustments. 3D LUT is a three-dimensional array where each element is an RGB triplet. As mentioned before, the dc->caps.color.dpp.hw_3d_lut describe if DPP 3D LUT is supported. The AMD driver-specific property advertise the size of a single dimension via LUT3D_SIZE property. Plane 3D LUT is a blog property where the data is interpreted as an array of struct drm_color_lut elements and the number of entries is LUT3D_SIZE cubic. The array contains samples from the approximated function. Values between samples are estimated by tetrahedral interpolation The array is accessed with three indices, one for each input dimension (color channel), blue being the outermost dimension, red the innermost. This distribution is better visualized when examining the code in [RFC PATCH 5/5] drm/amd/display: Fill 3D LUT from userspace by Alex Hung:
+	for (nib = 0; nib < 17; nib++)  
+		for (nig = 0; nig < 17; nig++)  
+			for (nir = 0; nir < 17; nir++)  
+				ind_lut = 3 * (nib + 17*nig + 289*nir);
+
+				rgb_area[ind].red = rgb_lib[ind_lut + 0];
+				rgb_area[ind].green = rgb_lib[ind_lut + 1];
+				rgb_area[ind].blue = rgb_lib[ind_lut + 2];
+				ind++;
+			 
+		 
+	 
In our driver-specific approach we opted to advertise it s behavior to the userspace instead of implicitly dealing with it in the kernel driver. AMD s hardware supports 3D LUTs with 17-size or 9-size (4913 and 729 entries respectively), and you can choose between 10-bit or 12-bit. In the current driver-specific work we focus on enabling only 17-size 12-bit 3D LUT, as in [PATCH v3 25/32] drm/amd/display: add plane 3D LUT support:
+		/* Stride and bit depth are not programmable by API yet.
+		 * Therefore, only supports 17x17x17 3D LUT (12-bit).
+		 */
+		lut->lut_3d.use_tetrahedral_9 = false;
+		lut->lut_3d.use_12bits = true;
+		lut->state.bits.initialized = 1;
+		__drm_3dlut_to_dc_3dlut(drm_lut, drm_lut3d_size, &lut->lut_3d,
+					lut->lut_3d.use_tetrahedral_9,
+					MAX_COLOR_3DLUT_BITDEPTH);
A refined control of 3D LUT parameters should go through a follow-up version or generic API. Setting 3D LUT to NULL means bypass. References:

AMD Plane Blend/Out Gamma: TF + 1D LUT Described by: dc->caps.color.dpp.ogam_ram The Blend/Out Gamma block applies the final touch-up before blending, allowing users to linearize content after 3D LUT and just before the blending. It supports both 1D LUT and pre-defined TF. We can see Shaper and Blend LUTs as 1D LUTs that are sandwich the 3D LUT. So, if we don t need 3D LUT transformations, we may want to only use Degamma block to linearize and skip Shaper, 3D LUT and Blend. Pre-defined transfer function:
  • there is no DPP Blend ROM. Curves are calculated by AMD color modules;
  • supported curves: Identity, sRGB EOTF, BT.709 inverse OETF, PQ EOTF, HLG inverse OETF, and Gamma 2.2, Gamma 2.4, Gamma 2.6 EOTF.
The 1D LUT currently accepts 4096 entries of 8-bit. The data is interpreted as an array of struct drm_color_lut elements. If plane_blend_tf_property != Identity TF, AMD color module will combine the user LUT values with pre-defined TF into the LUT parameters to be programmed. Setting TF = Identity/Default and LUT to NULL means bypass. References:

MPC Color Pipeline: After Blending (Per CRTC)

DRM CRTC Degamma 1D LUT The degamma lookup table (LUT) for converting framebuffer pixel data before apply the color conversion matrix. The data is interpreted as an array of struct drm_color_lut elements. Setting NULL means bypass. Not really supported. The driver is currently reusing the DPP degamma LUT block (dc->caps.color.dpp.dgam_ram and dc->caps.color.dpp.gamma_corr) for supporting DRM CRTC Degamma LUT, as explaning by [PATCH v3 20/32] drm/amd/display: reject atomic commit if setting both plane and CRTC degamma.

DRM CRTC 3x3 CTM Described by: dc->caps.color.mpc.gamut_remap It sets the current transformation matrix (CTM) apply to pixel data after the lookup through the degamma LUT and before the lookup through the gamma LUT. The data is interpreted as a struct drm_color_ctm. Setting NULL means bypass.

DRM CRTC Gamma 1D LUT + AMD CRTC Gamma TF Described by: dc->caps.color.mpc.ogam_ram After all that, you might still want to convert the content to wire encoding. No worries, in addition to DRM CRTC 1D LUT, we ve got a AMD CRTC gamma transfer function (TF) to make it happen. Possible TF values are defined by enum amdgpu_transfer_function. Pre-defined transfer functions:
  • there is no MPC Gamma ROM. Curves are calculated by AMD color modules.
  • supported curves: Identity, sRGB inverse EOTF, BT.709 OETF, PQ inverse EOTF, HLG OETF, and Gamma 2.2, Gamma 2.4, Gamma 2.6 inverse EOTF.
The 1D LUT currently accepts 4096 entries of 8-bit. The data is interpreted as an array of struct drm_color_lut elements. When setting CRTC Gamma TF (!= Identity) and LUT at the same time, the color module will combine the pre-defined TF and the custom LUT values into the LUT that s actually programmed. Setting TF = Identity/Default and LUT to NULL means bypass. References:

Others

AMD CRTC Shaper and 3D LUT We have previously worked on exposing CRTC shaper and CRTC 3D LUT, but they were removed from the AMD driver-specific color series because they lack userspace case. CRTC shaper and 3D LUT works similar to plane shaper and 3D LUT but after blending (MPC block). The difference here is that setting (not bypass) Shaper and Gamma blocks together are not expected, since both blocks are used to delinearize the input space. In summary, we either set Shaper + 3D LUT or Gamma.

Input and Output Color Space Conversion There are two other color capabilities of AMD display hardware that were integrated to DRM by previous works and worth a brief explanation here. The DC Input CSC sets pre-defined coefficients from the values of DRM plane color_range and color_encoding properties. It is used for color space conversion of the input content. On the other hand, we have de DC Output CSC (OCSC) sets pre-defined coefficients from DRM connector colorspace properties. It is uses for color space conversion of the composed image to the one supported by the sink. References:

The search for rainbow treasures is not over yet If you want to understand a little more about this work, be sure to watch Joshua and I presented two talks at XDC 2023 about AMD/Steam Deck colors on Gamescope: In the time between the first and second part of this blog post, Uma Shashank and Chaitanya Kumar Borah published the plane color pipeline for Intel and Harry Wentland implemented a generic API for DRM based on VKMS support. We discussed these two proposals and the next steps for Color on Linux during the Color Management workshop at XDC 2023 and I briefly shared workshop results in the 2023 XDC lightning talk session. The search for rainbow treasures is not over yet! We plan to meet again next year in the 2024 Display Hackfest in Coru a-Spain (Igalia s HQ) to keep up the pace and continue advancing today s display needs on Linux. Finally, a HUGE thank you to everyone who worked with me on exploring AMD s color capabilities and making them available in userspace.

4 November 2023

Dirk Eddelbuettel: RcppEigen 0.3.3.9.4 on CRAN: Maintenance, Matrix Changes

A new release 0.3.3.9.4 of RcppEigen arrived on CRAN yesterday, and went to Debian today. Eigen is a C++ template library for linear algebra: matrices, vectors, numerical solvers, and related algorithms. This update contains a small amount of the usual maintenance (see below), along with a very nice pull request by Mikael Jagan which simplifies to interface with the Matrix package and inparticular the CHOLMOD library that is part of SuiteSparse. This release is coordinated with lme4 and OpenMx which are also being updated. The complete NEWS file entry follows.

Changes in RcppEigen version 0.3.3.9.4 (2023-11-01)
  • The CITATION file has been updated for the new bibentry style.
  • The package skeleton generator has been updated and no longer sets an Imports:.
  • Some README.md URLs and badged have been updated.
  • The use of -fopenmp has been documented in Makevars, and a simple thread-count reporting function has been added.
  • The old manual src/init.c has been replaced by an autogenerated version, the RcppExports file have regenerated
  • The interface to package Matrix has been updated and simplified thanks to an excllent patch by Mikael Jagan.
  • The new upload is coordinated with packages lme4 and OpenMx.

Courtesy of CRANberries, there is also a diffstat report for the most recent release. If you like this or other open-source work I do, you can sponsor me at GitHub.

This post by Dirk Eddelbuettel originated on his Thinking inside the box blog. Please report excessive re-aggregation in third-party for-profit settings.

29 October 2023

Aigars Mahinovs: Figuring out finances part 4

At the end of the last part of this, we got a Home Assistant OS installation that contains in itself a Firefly III instance and that contains all the current financial information. Now I will try to connect the two. While it could be nice to create a fully-featured integration for Firefly III to Home Assistant to communicate all interesting values and events, I have an interest on programming a more advanced data point calculation for my budget needs, so a less generic, but more flexible approch is a better one for me. So I was quite interested when among the addons in the Home Assistant Addon Store I saw AppDaemon - a way to simply integrate arbitrary Python processing with Home Assistant. Let's see if that can do what I want. For start, after reading the tutorial , I wanted to create a simple script that would use Firefly III REST API to read the current balance of my main account and then send that to Home Assistant as a sensor value, which then can be displayed on a dashboard. As a quick try I modified the provided hello_world.py that is included in the default AppDaemon installation:
import requests
from datetime import datetime
import appdaemon.plugins.hass.hassapi as hass
app_token = "<FIREFLY_PERSONAL_ACCESS_TOKEN>"
firefly_url = "<FIREFLY_URL>"
class HelloWorld(hass.Hass):
    def initialize(self):
        self.run_every(self.set_asset, "now", 60 * 60)
    def set_asset(self, kwargs):
        ent = self.get_entity("sensor.firefly3_asset_sparkasse_main")
        if not ent.exists():
            ent.add(
                state=0.0,
                attributes= 
                    "native_value": 0.0,
                    "native_unit_of_measurement": "EUR",
                    "state_class": "measurement",
                    "device_class": "monetary",
                    "current_balance_date": datetime.now(),
                 )
        r = requests.get(
            firefly_url + "/api/v1/accounts?type=asset",
            headers= 
                "Authorization": "Bearer " + app_token,
                "Accept": "application/vnd.api+json",
                "Content-Type": "application/json",
         )
        data = r.json()
        for account in data["data"]:
            if not "attributes" in account or "name" not in account["attributes"]:
                continue
            if account["attributes"]["name"] != "Sparkasse giro":
                continue
            self.log("Account :" + str(account["attributes"]))
            ent.set_state(
                state=account["attributes"]["current_balance"],
                attributes= 
                    "native_value": account["attributes"]["current_balance"],
                    "current_balance_date": datetime.fromisoformat(account["attributes"]["current_balance_date"]),
                 )
            self.log("Entity updated")
It uses a URL and personal access token to access Firefly III API, gets the asset accounts information, then extracts info about current balance and balance date of my main account and then creates and/or updates a "sensor" value into Home Assistant. This sensor is with metadata marked as a monetary value and as a measurement. This makes Home Assistant track this value in the database as a graphable changing value. I modified the file using the File Editor addon to edit the /config/appdaemon/apps/hello.py file. Each time the file is saved it is reloaded and logs can be seen in the AppDaemon Logs section - main_log for logging messages or error_log if there is a crash. Useful to know that requests library is included, but it hard to see in the docks what else is included or if there is an easy way to install extra Python packages. This is already a very nice basis for custom value insertion into Home Assistant - whatever you can with a Python script extract or calculate, you can also inject into Home Assistant. With even this simple approach you can monitor balances, budgets, piggy-banks, bill payment status and even sum of transactions in particular catories in a particular time window. Especially interesting data can be found in the insight section of the Firefly III API. The script above uses a trigger like self.run_every(self.set_asset, "now", 60 * 60) to simply run once per hour. The data in Firefly will not be updated too often anyway, at least not until we figure out how to make bank connection run automatically without user interaction and not screw up already existing transactions along the way. In theory a webhook API of the Firefly III could be used to trigger the data update instantly when any transaction is created or updated. Possibly even using Home Assistant webhook integration. Hmmm. Maybe. Who am I kiddind? I am going to make that work, for sure! :D But first - how about figuring out the future? So what I want to do? In short, I want to predict what will be the balance on my main account just before the next months salary comes in. To do this I would:
  • take the current balance of the main account
  • if this months salary is not paid out yet, then add that into the balance
  • deduct all still unpaid bills that are due between now and the target date
  • if the credit card account has not yet been reset to the main account, deduct current amount on the cards
  • if credit card account has been reset, but not from main account deducted yet, deduct the reset amount
To do that I need to use the Firefly API to read: current account info, status of all bills including next due date and amount, transfer transactions between credit cards and main account and something that would store the expected salary date and amount. Ideally I'd use a recurring transaction or a income bill for this, but Firefly is not really cooperating with that. The easiest would be just to hardcode that in the script itself. And this is what I have come up with so far. To make the development process easier, I separated put the params for the API key and salary info and app params for the month to predict for, and predict both this and next months balances at the same time. I edited the script locally with Neovim and also ran it locally with a few mocks, uploading to Home Assistant via the SSH addon when the local executions looked good. So what's next? Well, need to somewhat automate the sync with the bank (if at all possible). And for sure take a regular database and config backup :D

22 October 2023

Aigars Mahinovs: Figuring out finances part 3

So now that I have something that looks very much like a budgeting setup going, I am going to .. delete it! Why? Well, at the end of the last part of this, the Firefly III instance was running on a tiny Debian server in a Docker container right next to another Docker container that is running the main user of this server - a Home Assistant instance that has been managing my home for several years already. So why change that? See, there is one bit of knowledge that is very crucial to your Home Assistant experience, which is not really emphasised enough in the Home Assistant documentation. In fact back when I was getting into the Home Assistant both the main documentation and basically all the guides around were just coming off the hype of Docker disrupting everything and that is a big reason why everyone suggested to install and use Home Assistant as a Docker container on top of any kind of stable OS. In fact I used to run it for years on my TerraMaster NAS, just so that I don't have a separate home server running 24/7 at home and just have everything inside the very compact NAS case. So here is the thing you NEED to know - Home Assistant Container is DEMO version of Home Assistant! If you want to have a full Home Assistant experience and use the knowledge of the huge community around the HA space, you have to use the Home Assistant OS. Ideally on dedicated hardware. Ideally on HA Green box, but any tiny PC would also work great. Raspberry Pi 4+ is common, but quite weak as the network size grows and especially the SD card for storage gets old very fast. Get a real small x86 PC with at least 4Gb RAM and a NVME SSD (eMMC is fine too). You want to have an Ethernet port and a few free USB ports. I would also suggest immediately getting HA SkyConnect adapter that can do Zigbee networking and will do Matter soon (tm). I am making do with a SonOff Zigbee gateway, but it is quite hacky to get working and your whole Zigbee communication breaks down if the WiFi goes down - suboptimal. So I took a backup of the Home Assistant instance using it's build-in tools. I took an export of my fully configured Firefly III instance and proceeded to wipe the drive of the NUC. That was not a smart idea. :D On the Home Assitant side I was really frustrated by the documentation that was really focused on users that are (likely) using Windows and are using an SD card in something like Raspberry Pi to get Home Assistant OS running. It recommended downloading Etcher to write the image to the boot medium. That is a really weird piece of software that managed to actually crash consistently when I was trying to run it from Debian Live or Ubuntu Live on my NUC. It took me way too long to give up and try something much simpler - dd. xzcat haos_generic-x86-64-11.0.img.xz dd of=/dev/mmcblk0 bs=1M That just worked, prefectly and really fast. If you want to use a GUI in a live environment, then just using the gnome-disk-utility ("Disks" in Gnome menu) and using the "Restore Disk Image ..." on a partition would work just as well. It even supports decompressing the XZ images directly while writing. But that image is small, will it not have a ton of unused disk space behind the fixed install partition? Yes, it will ... until first boot. The HA OS takes over the empty space after its install partition on the first boot-up and just grows its main partition to take up all the remaining space. Smart. After first boot is completed, the first boot wizard can be accessed via your web browser and one of the prominent buttons there is restoring from backup. So you just give it the backup file and wait. Sadly the restore does not actually give any kind of progress, so your only way to figure out when it is done is opening the same web adress in another browser tab and refresh periodically - after restoring from backup it just boots into the same config at it had before - all the settings, all the devices, all the history is preserved. Even authentification tokens are preserved so if yu had a Home Assitant Mobile installed on your phone (both for remote access and to send location info and phone state, like charging, to HA to trigger automations) then it will just suddenly start working again without further actions needed from your side. That is an almost perfect backup/restore experience. The first thing you get for using the OS version of HA is easy automatic update that also automatically takes a backup before upgrade, so if anything breaks you can roll back with one click. There is also a command-line tool that allows to upgrade, but also downgrade ha-core and other modules. I had to use it today as HA version 23.10.4 actually broke support for the Sonoff bridge that I am using to control Zigbee devices, which are like 90% of all smart devices in my home. Really helpful stuff, but not a must have. What is a must have and that you can (really) only get with Home Assistant Operating System are Addons. Some addons are just normal servers you can run alongside HA on the same HA OS server, like MariaDB or Plex or a file server. That is not the most important bit, but even there the software comes pre-configured to use in a home server configuration and has a very simple config UI to pre-configure key settings, like users, passwords and database accesses for MariaDB - you can litereally in a few clicks and few strings make serveral users each with its own access to its own database. Couple more clicks and the DB is running and will be kept restarted in case of failures. But the real gems in the Home Assistant Addon Store are modules that extend Home Assitant core functionality in way that would be really hard or near impossible to configure in Home Assitant Container manually, especially because no documentation has ever existed for such manual config - everyone just tells you to install the addon from HA Addon store or from HACS. Or you can read the addon metadata in various repos and figure out what containers it actually runs with what settings and configs and what hooks it puts into the HA Core to make them cooperate. And then do it all over again when a new version breaks everything 6 months later when you have already forgotten everything. In the Addons that show up immediately after installation are addons to install the new Matter server, a MariaDB and MQTT server (that other addons can use for data storage and message exchange), Z-Wave support and ESPHome integration and very handy File manager that includes editors to edit Home Assitant configs directly in brower and SSH/Terminal addon that boht allows SSH connection and also a web based terminal that gives access to the OS itself and also to a comand line interface, for example, to do package downgrades if needed or see detailed logs. And also there is where you can get the features that are the focus this year for HA developers - voice enablers. However that is only a beginning. Like in Debian you can add additional repositories to expand your list of available addons. Unlike Debian most of the amazing software that is available for Home Assistant is outside the main, official addon store. For now I have added the most popular addon repository - HACS (Home Assistant Community Store) and repository maintained by Alexbelgium. The first includes things like NodeRED (a workflow based automation programming UI), Tailscale/Wirescale for VPN servers, motionEye for CCTV control, Plex for home streaming. HACS also includes a lot of HA UI enhacement modules, like themes, custom UI control panels like Mushroom or mini-graph-card and integrations that provide more advanced functions, but also require more knowledge to use, like Local Tuya - that is harder to set up, but allows fully local control of (normally) cloud-based devices. And it has AppDaemon - basically a Python based automation framework where you put in Python scrips that get run in a special environment where they get fed events from Home Assistant and can trigger back events that can control everything HA can and also do anything Python can do. This I will need to explore later. And the repository by Alex includes the thing that is actually the focus of this blog post (I know :D) - Firefly III addon and Firefly Importer addon that you can then add to your Home Assistant OS with a few clicks. It also has all kinds of addons for NAS management, photo/video server, book servers and Portainer that lets us setup and run any Docker container inside the HA OS structure. HA OS will detect this and warn you about unsupported processes running on your HA OS instance (nice security feature!), but you can just dismiss that. This will be very helpful very soon. This whole environment of OS and containers and apps really made me think - what was missing in Debian that made the talented developers behind all of that to spend the immense time and effor to setup a completely new OS and app infrastructure and develop a completel paraller developer community for Home Assistant apps, interfaces and configurations. Is there anything that can still be done to make HA community and the general open source and Debian community closer together? HA devs are not doing anything wrong: they are using the best open source can provide, they bring it to people whould could not install and use it otherwise, they are contributing fixes and improvements as well. But there must be some way to do this better, together. So I installed MariaDB, create a user and database for Firefly. I installed Firefly III and configured it to use the MariaDB with the web config UI. When I went into the Firefly III web UI I was confronted with the normal wizard to setup a new instance. And no reference to any backup restore. Hmm, ok. Maybe that goes via the Importer? So I make an access token again, configured the Importer to use that, configured the Nordlinger bank connection settings. Then I tried to import the export that I downloaded from Firefly III before. The importer did not auto-recognose the format. Turns out it is just a list of transactions ... It can only be barely useful if you first manually create all the asset accounts with the same names as before and even then you'll again have to deal with resolving the problem of transfers showing up twice. And all of your categories (that have not been used yet) are gone, your automation rules and bills are gone, your budgets and piggy banks are gone. Boooo. It will be easier for me to recreate my account data from bank exports again than to resolve data in that transaction export. Turns out that Firefly III documenation explicitly recommends making a mysqldump of your own and not rely on anything in the app itself for backup purposes. Kind of sad this was not mentioned in the export page that sure looked a lot like a backup :D After doing all that work all over again I needed to make something new not to feel like I wasted days of work for no real gain. So I started solving a problem I had for a while already - how do I add cash transations to the system when I am out of the house with just my phone in the hand? So far my workaround has been just sending myself messages in WhatsApp with the amount and description of any cash expenses. Two solutions are possible: app and bot. There are actually multiple Android-based phone apps that work with Firefly III API to do full financial management from the phone. However, after trying it out, that is not what I will be using most of the time. First of all this requires your Firefly III instance to be accessible from the Internet. Either via direct API access using some port forwarding and secured with HTTPS and good access tokens, or via a VPN server redirect that is installed on both HA and your phone. Tailscale was really easy to get working. But the power has its drawbacks - adding a new cash transaction requires opening the app, choosing new transaction view, entering descriptio, amount, choosing "Cash" as source account and optionally choosing destination expense account, choosing category and budget and then submitting the form to the server. Sadly none of that really works if you have no Internet or bad Internet at the place where you are using cash. And it's just too many steps. Annoying. An easier alternative is setting up a Telegram bot - it is running in a custom Docker container right next to your Firefly (via Portainer) and you talk to it via a custom Telegram chat channel that you create very easily and quickly. And then you can just tell it "Coffee 5" and it will create a transaction from the (default) cash account in 5 amount with description "Coffee". This part also works if you are offline at the moment - the bot will receive the message once you get back online. You can use Telegram bot menu system to edit the transaction to add categories or expense accounts, but this part only work if you are online. And the Firefly instance does not have to be online at all. Really nifty. So next week I will need to write up all the regular payments as bills in Firefly (again) and then I can start writing a Python script to predict my (financial) future!

13 October 2023

Reproducible Builds (diffoscope): diffoscope 251 released

The diffoscope maintainers are pleased to announce the release of diffoscope version 251. This version includes the following changes:
* If the equivalent of  file -i  returns text/plain, fallback to comparing
  this file as a text file. This especially helps when file(1) miscategorises
  text files as some esoteric type. (Closes: Debian:#1053668)
* Update copyright years.
You find out more by visiting the project homepage.

11 October 2023

Russell Coker: PinePhone Status

4 months ago I got my PinePhonePro [1]. Since then I have got SE Linux working on it to the stage of allowing it to boot correctly with Debian/Unstable, login with the user_t domain (minimum privilege for the graphical user) and make and receive calls. I finished getting SE Linux working reasonably well 3 days ago and most (but not all) of the SE Linux policy is in Debian now. I ve been getting good at Github PRs and I m sending a lot of policy upstream, so the next version of Debian will have a much smaller diff from the upstream Refpolicy. I have been running the PinePhone with Plasma Mobile because I prefer KDE, I would run GNOME/Phoc if it gave significantly better functionality. 3 days ago I moved my main SIM (the one with the number that people call about work etc) to my PinePhone and tried running it as my main phone. Today I gave up on that. My Android History The last phone I had that did everything I needed was a Huawei Mate 10 Pro that I bought refurbished in June 2019 for $389. The Mate 10 Pro runs Android with the Google Play store and has been quite unremarkable which is presumably why I forgot to blog about it when I got it, it was a slight upgrade over the Huawei Mate 9 [2] that I had used for 2 years before that. In April 2022 I tried using a Huawei Nova 7i as my main phone without Google Play programs or services [3]. That experiment was a failure as I couldn t get NextCloud to work for Calendaring and Contacts. It could be that I stuffed something up when trying that, but I put more skill and effort into trying to get it to work than most people ever would. The Nova 7i is a very slick phone, faster and nicer than the Mate 10 Pro (as expected being 2 years newer) while also having ridiculously long battery life. The Nova 7i when always on running the SchildiChat Matrix client and the Conversations Jabber client it will use less than 10% battery in a 8 hour work day. As nice as the Nova 7i is for the core functions I still need to have Play Store apps for LinkedIn, Twitter, Facebook, Zoom, etc. Which meant connecting the Mate 10 Pro via Wifi. As slick as the Nova 7i is for non-Google stuff running it and the Mate 10 Pro is a medium amount of pain for a small amount of freedom. So now I have for the moment abandoned the Nova 7i and gone back to the Mate 10 Pro. What I will try to do is to either forcibly install Google Play on the Nova 7i to make it my proprietary phone or to install an open distribution of Linux (IE not Android) to make it at least a small tablet which incidentally is much more powerful than a PinePhonePro. Issues With the PinePhonePro The battery charges very slowly (as much as 50 hours estimated charge time) and discharges fast. When used in a typical way in Caffeine mode to stop suspend so I can ssh to it etc it won t come close to lasting an 8 hour day. Also it will only take 5V charging and ideally wants 5V 3A charging which most chargers won t do. The charging speed over regular USB ports is very slow, sometimes stating it will take as much as 50 hours to charge. A phone that gets below 50% charge in less than 4 hours and can t be charged at a reasonable speed from a USB port on a laptop or monitor is going to be a major pain to use in the office. I don t think this can be fixed in software, we can alleviate it by making software more CPU efficient and by enabling various hardware sleep modes more effectively but the slow charging is a hardware issue that can t be fixed. The phone call quality is poor. Usually when on a call I hear static and sometimes the person at the other end appears to hear nothing. Also the UI for calls is different from Android which makes it take longer to answer a call and gives more missed calls. The UI issue is a combination of software and habits, both of which can be changed. But the call quality may be a hardware issue. I don t know if it s a hardware issue specific to my phone or something related to the PinePhonePro on the Telstra network. Clicking on notification in the drop-down doesn t take me to the app. I don t know if this is regarded as a bug by the Plasma-Mobile developers. Also notifications aren t displayed on the lock screen and there doesn t seem to be a configuration option to enable this. The Plasma-Mobile configuration for the wifi hotspot is difficult. There is no button for it in the drop-down menu (called Quicksettings in Plasma-Mobile) and no way of easily determining whether it s in hotspot or wifi client mode. This isn t an insurmountable problem and the worst-case is that I could write a script to do it, but it s still annoying. There is apparent support in the desktop version of KDE for syncing contacts from Google and I could probably get that working (although I failed last time I tried on the desktop), but it is a pain. Conclusion Most of the problems are software related and therefore I can get involved in solving them. I plan to keep working on these things. If all the software had worked in an ideal manner then I would have spent more time investigating the hardware issues of battery life and charge time and the quality of calls. I now have my Librem5 [4] running Debian so I will be able to compare call quality with the PinePhonePro. If I m unable to get the PinePhonePro working adequately then maybe making the Librem5 my main phone will be an option. I hope that by early next year I will be able to make another test at using a FOSS phone my main phone. In the mean time I can still work on convergence and other things.

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