Search Results: "ana"

2 January 2024

Matthew Garrett: Dealing with weird ELF libraries

Libraries are collections of code that are intended to be usable by multiple consumers (if you're interested in the etymology, watch this video). In the old days we had what we now refer to as "static" libraries, collections of code that existed on disk but which would be copied into newly compiled binaries. We've moved beyond that, thankfully, and now make use of what we call "dynamic" or "shared" libraries - instead of the code being copied into the binary, a reference to the library function is incorporated, and at runtime the code is mapped from the on-disk copy of the shared object[1]. This allows libraries to be upgraded without needing to modify the binaries using them, and if multiple applications are using the same library at once it only requires that one copy of the code be kept in RAM.

But for this to work, two things are necessary: when we build a binary, there has to be a way to reference the relevant library functions in the binary; and when we run a binary, the library code needs to be mapped into the process.

(I'm going to somewhat simplify the explanations from here on - things like symbol versioning make this a bit more complicated but aren't strictly relevant to what I was working on here)

For the first of these, the goal is to replace a call to a function (eg, printf()) with a reference to the actual implementation. This is the job of the linker rather than the compiler (eg, if you use the -c argument to tell gcc to simply compile to an object rather than linking an executable, it's not going to care about whether or not every function called in your code actually exists or not - that'll be figured out when you link all the objects together), and the linker needs to know which symbols (which aren't just functions - libraries can export variables or structures and so on) are available in which libraries. You give the linker a list of libraries, it extracts the symbols available, and resolves the references in your code with references to the library.

But how is that information extracted? Each ELF object has a fixed-size header that contains references to various things, including a reference to a list of "section headers". Each section has a name and a type, but the ones we're interested in are .dynstr and .dynsym. .dynstr contains a list of strings, representing the name of each exported symbol. .dynsym is where things get more interesting - it's a list of structs that contain information about each symbol. This includes a bunch of fairly complicated stuff that you need to care about if you're actually writing a linker, but the relevant entries for this discussion are an index into .dynstr (which means the .dynsym entry isn't sufficient to know the name of a symbol, you need to extract that from .dynstr), along with the location of that symbol within the library. The linker can parse this information and obtain a list of symbol names and addresses, and can now replace the call to printf() with a reference to libc instead.

(Note that it's not possible to simply encode this as "Call this address in this library" - if the library is rebuilt or is a different version, the function could move to a different location)

Experimentally, .dynstr and .dynsym appear to be sufficient for linking a dynamic library at build time - there are other sections related to dynamic linking, but you can link against a library that's missing them. Runtime is where things get more complicated.

When you run a binary that makes use of dynamic libraries, the code from those libraries needs to be mapped into the resulting process. This is the job of the runtime dynamic linker, or RTLD[2]. The RTLD needs to open every library the process requires, map the relevant code into the process's address space, and then rewrite the references in the binary into calls to the library code. This requires more information than is present in .dynstr and .dynsym - at the very least, it needs to know the list of required libraries.

There's a separate section called .dynamic that contains another list of structures, and it's the data here that's used for this purpose. For example, .dynamic contains a bunch of entries of type DT_NEEDED - this is the list of libraries that an executable requires. There's also a bunch of other stuff that's required to actually make all of this work, but the only thing I'm going to touch on is DT_HASH. Doing all this re-linking at runtime involves resolving the locations of a large number of symbols, and if the only way you can do that is by reading a list from .dynsym and then looking up every name in .dynstr that's going to take some time. The DT_HASH entry points to a hash table - the RTLD hashes the symbol name it's trying to resolve, looks it up in that hash table, and gets the symbol entry directly (it still needs to resolve that against .dynstr to make sure it hasn't hit a hash collision - if it has it needs to look up the next hash entry, but this is still generally faster than walking the entire .dynsym list to find the relevant symbol). There's also DT_GNU_HASH which fulfills the same purpose as DT_HASH but uses a more complicated algorithm that performs even better. .dynamic also contains entries pointing at .dynstr and .dynsym, which seems redundant but will become relevant shortly.

So, .dynsym and .dynstr are required at build time, and both are required along with .dynamic at runtime. This seems simple enough, but obviously there's a twist and I'm sorry it's taken so long to get to this point.

I bought a Synology NAS for home backup purposes (my previous solution was a single external USB drive plugged into a small server, which had uncomfortable single point of failure properties). Obviously I decided to poke around at it, and I found something odd - all the libraries Synology ships were entirely lacking any ELF section headers. This meant no .dynstr, .dynsym or .dynamic sections, so how was any of this working? nm asserted that the libraries exported no symbols, and readelf agreed. If I wrote a small app that called a function in one of the libraries and built it, gcc complained that the function was undefined. But executables on the device were clearly resolving the symbols at runtime, and if I loaded them into ghidra the exported functions were visible. If I dlopen()ed them, dlsym() couldn't resolve the symbols - but if I hardcoded the offset into my code, I could call them directly.

Things finally made sense when I discovered that if I passed the --use-dynamic argument to readelf, I did get a list of exported symbols. It turns out that ELF is weirder than I realised. As well as the aforementioned section headers, ELF objects also include a set of program headers. One of the program header types is PT_DYNAMIC. This typically points to the same data that's present in the .dynamic section. Remember when I mentioned that .dynamic contained references to .dynsym and .dynstr? This means that simply pointing at .dynamic is sufficient, there's no need to have separate entries for them.

The same information can be reached from two different locations. The information in the section headers is used at build time, and the information in the program headers at run time[3]. I do not have an explanation for this. But if the information is present in two places, it seems obvious that it should be able to reconstruct the missing section headers in my weird libraries? So that's what this does. It extracts information from the DYNAMIC entry in the program headers and creates equivalent section headers.

There's one thing that makes this more difficult than it might seem. The section header for .dynsym has to contain the number of symbols present in the section. And that information doesn't directly exist in DYNAMIC - to figure out how many symbols exist, you're expected to walk the hash tables and keep track of the largest number you've seen. Since every symbol has to be referenced in the hash table, once you've hit every entry the largest number is the number of exported symbols. This seemed annoying to implement, so instead I cheated, added code to simply pass in the number of symbols on the command line, and then just parsed the output of readelf against the original binaries to extract that information and pass it to my tool.

Somehow, this worked. I now have a bunch of library files that I can link into my own binaries to make it easier to figure out how various things on the Synology work. Now, could someone explain (a) why this information is present in two locations, and (b) why the build-time linker and run-time linker disagree on the canonical source of truth?

[1] "Shared object" is the source of the .so filename extension used in various Unix-style operating systems
[2] You'll note that "RTLD" is not an acryonym for "runtime dynamic linker", because reasons
[3] For environments using the GNU RTLD, at least - I have no idea whether this is the case in all ELF environments

comment count unavailable comments

Thomas Koch: Waiting for a STATE folder in the XDG basedir spec

Posted on February 18, 2014
Tags: debian, free software
The XDG Basedirectory specification proposes default homedir folders for the categories DATA (~/.local/share), CONFIG (~/.config) and CACHE (~/.cache). One category however is missing: STATE. This category has been requested several times but nothing happened. Examples for state data are: The missing STATE category is especially annoying if you re managing your dotfiles with a VCS (e.g. via VCSH) and you care to keep your homedir tidy. If you re as annoyed as me about the missing STATE category, please voice your opinion on the XDG mailing list. Of course it s a very long way until applications really use such a STATE directory. But without a common standard it will never happen.

1 January 2024

Russ Allbery: 2023 Book Reading in Review

In 2023, I finished and reviewed 53 books, continuing a trend of year-over-year increases and of reading the most books since 2012 (the last year I averaged five books a month). Reviewing continued to be uneven, with a significant slump in the summer and smaller slumps in February and November, and a big clump of reviews finished in October in addition to my normal year-end reading and reviewing vacation. The unevenness this year was mostly due to finishing books and not writing reviews immediately. Reviews are much harder to write when the finished books are piling up, so one goal for 2024 is to not let that happen again. I enter the new year with one book finished and not yet reviewed, after reading a book about every day and a half during my December vacation. I read two all-time favorite books this year. The first was Emily Tesh's debut novel Some Desperate Glory, which is one of the best space opera novels I have ever read. I cannot improve on Shelley Parker-Chan's blurb for this book: "Fierce and heartbreakingly humane, this book is for everyone who loved Ender's Game, but Ender's Game didn't love them back." This is not hard science fiction but it is fantastic character fiction. It was exactly what I needed in the middle of a year in which I was fighting a "burn everything down" mood. The second was Night Watch by Terry Pratchett, the 29th Discworld and 6th Watch novel. Throughout my Discworld read-through, Pratchett felt like he was on the cusp of a truly stand-out novel, one where all the pieces fit and the book becomes something more than the sum of its parts. This was that book. It's a book about ethics and revolutions and governance, but also about how your perception of yourself changes as you get older. It does all of the normal Pratchett things, just... better. While I would love to point new Discworld readers at it, I think you do have to read at least the Watch novels that came before it for it to carry its proper emotional heft. This was overall a solid year for fiction reading. I read another 15 novels I rated 8 out of 10, and 12 that I rated 7 out of 10. The largest contributor to that was my Discworld read-through, which was reliably entertaining throughout the year. The run of Discworld books between The Fifth Elephant (read late last year) and Wintersmith (my last of this year) was the best run of Discworld novels so far. One additional book I'll call out as particularly worth reading is Thud!, the Watch novel after Night Watch and another excellent entry. I read two stand-out non-fiction books this year. The first was Oliver Darkshire's delightful memoir about life as a rare book seller, Once Upon a Tome. One of the things I will miss about Twitter is the regularity with which I stumbled across fascinating people and then got to read their books. I'm off Twitter permanently now because the platform is designed to make me incoherently angry and I need less of that in my life, but it was very good at finding delightfully quirky books like this one. My other favorite non-fiction book of the year was Michael Lewis's Going Infinite, a profile of Sam Bankman-Fried. I'm still bemused at the negative reviews that this got from people who were upset that Lewis didn't turn the story into a black-and-white morality play. Bankman-Fried's actions were clearly criminal; that's not in dispute. Human motivations can be complex in ways that are irrelevant to the law, and I thought this attempt to understand that complexity by a top-notch storyteller was worthy of attention. Also worth a mention is Tony Judt's Postwar, the first book I reviewed in 2023. A sprawling history of post-World-War-II Europe will never have the sheer readability of shorter, punchier books, but this was the most informative book that I read in 2023. 2024 should see the conclusion of my Discworld read-through, after which I may return to re-reading Mercedes Lackey or David Eddings, both of which I paused to make time for Terry Pratchett. I also have another re-read similar to my Chronicles of Narnia reviews that I've been thinking about for a while. Perhaps I will start that next year; perhaps it will wait for 2025. Apart from that, my intention as always is to read steadily, write reviews as close to when I finished the book as possible, and make reading time for my huge existing backlog despite the constant allure of new releases. Here's to a new year full of more new-to-me books and occasional old favorites. The full analysis includes some additional personal reading statistics, probably only of interest to me.

Tim Retout: Prevent DOM-XSS with Trusted Types - a smarter DevSecOps approach

It can be incredibly easy for a frontend developer to accidentally write a client-side cross-site-scripting (DOM-XSS) security issue, and yet these are hard for security teams to detect. Vulnerability scanners are slow, and suffer from false positives. Can smarter collaboration between development, operations and security teams provide a way to eliminate these problems altogether? Google claims that Trusted Types has all but eliminated DOM-XSS exploits on those of their sites which have implemented it. Let s find out how this can work!

DOM-XSS vulnerabilities are easy to write, but hard for security teams to catch It is very easy to accidentally introduce a client-side XSS problem. As an example of what not to do, suppose you are setting an element s text to the current URL, on the client side: 
// Don't do this
para.innerHTML = location.href;
Unfortunately, an attacker can now manipulate the URL (and e.g. send this link in a phishing email), and any HTML tags they add will be interpreted by the user s browser. This could potentially be used by the attacker to send private data to a different server. Detecting DOM-XSS using vulnerability scanning tools is challenging - typically this requires crawling each page of the website and attempting to detect problems such as the one above, but there is a significant risk of false positives, especially as the complexity of the logic increases. There are already ways to avoid these exploits developers should validate untrusted input before making use of it. There are libraries such as DOMPurify which can help with sanitization.1 However, if you are part of a security team with responsibility for preventing these issues, it can be complex to understand whether you are at risk. Different developer teams may be using different techniques and tools. It may be impossible for you to work closely with every developer so how can you know that the frontend team have used these libraries correctly?

Trusted Types closes the DevSecOps feedback loop for DOM-XSS, by allowing Ops and Security to verify good Developer practices Trusted Types enforces sanitization in the browser2, by requiring the web developer to assign a particular kind of JavaScript object rather than a native string to .innerHTML and other dangerous properties. Provided these special types are created in an appropriate way, then they can be trusted not to expose XSS problems. This approach will work with whichever tools the frontend developers have chosen to use, and detection of issues can be rolled out by infrastructure engineers without requiring frontend code changes.

Content Security Policy allows enforcement of security policies in the browser itself Because enforcing this safer approach in the browser for all websites would break backwards-compatibility, each website must opt-in through Content Security Policy headers. Content Security Policy (CSP) is a mechanism that allows web pages to restrict what actions a browser should execute on their page, and a way for the site to receive reports if the policy is violated. Diagram showing a browser communicating with a web server. Content-Security-Policy headers are returned by the URL “/”, and the browser reports any security violations to “/csp”. Figure 1: Content-Security-Policy browser communication This is revolutionary, because it allows servers to receive feedback in real time on errors that may be appearing in the browser s console.

Trusted Types can be rolled out incrementally, with continuous feedback Web.dev s article on Trusted Types explains how to safely roll out the feature using the features of CSP itself:
  • Deploy a CSP collector if you haven t already
  • Switch on CSP reports without enforcement (via Content-Security-Policy-Report-Only headers)
  • Iteratively review and fix the violations
  • Switch to enforcing mode when there are a low enough rate of reports
Static analysis in a continuous integration pipeline is also sensible you want to prevent regressions shipping in new releases before they trigger a flood of CSP reports. This will also give you a chance of finding any low-traffic vulnerable pages.

Smart security teams will use techniques like Trusted Types to eliminate entire classes of bugs at a time Rather than playing whack-a-mole with unreliable vulnerability scanning or bug bounties, techniques such as Trusted Types are truly in the spirit of Secure by Design build high quality in from the start of the engineering process, and do this in a way which closes the DevSecOps feedback loop between your Developer, Operations and Security teams.
  1. Sanitization libraries are especially needed when the examples become more complex, e.g. if the application must manipulate the input. DOMPurify version 1.0.9 also added Trusted Types support, so can still be used to help developers adopt this feature.
  2. Trusted Types has existed in Chrome and Edge since 2020, and should soon be coming to Firefox as well. However, it s not necessary to wait for Firefox or Safari to add support, because the large market share of Chrome and Edge will let you identify and fix your site s DOM-XSS issues, even if you do not set enforcing mode, and users of all browsers will benefit. Even so, it is great that Mozilla is now on board.

Paul Wise: FLOSS Activities December 2023

Focus This month I didn't have any particular focus. I just worked on issues in my info bubble.

Changes

Issues
  • Feature in UDD
  • Conffile removal needed in neomutt
  • dpkg vendor config needed in Armbian
  • New SWH listers needed for depp & depp (different projects)

Review

Administration
  • Debian wiki: approve accounts

Communication
  • Respond to queries from Debian users and contributors on the mailing lists and IRC

Sponsors The SWH work was sponsored. All other work was done on a volunteer basis.

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

29 December 2023

Ulrike Uhlig: How do kids conceive the internet? - part 4

Read all parts of the series Part 1 // Part 2 // Part 3 // Part 4 I ve been wanting to write this post for over a year, but lacked energy and time. Before 2023 is coming to an end, I want to close this series and share some more insights with you and hopefully provide you with a smile here and there. For this round of interviews, four more kids around the ages of 8 to 13 were interviewed, 3 of them have a US background these 3 interviews were done by a friend who recorded these interviews for me, thank you! As opposed to the previous interviews, these four kids have parents who have a more technical professional background. And this seems to make a difference: even though none of these kids actually knew much better how the internet really works than the other kids that I interviewed, specifically in terms of physical infrastructures, they were much more confident in using the internet, they were able to more correctly name things they see on the internet, and they had partly radical ideas about what they would like to learn or what they would want to change about the internet! Looking at these results, I think it s safe to say that social reproduction is at work and that we need to improve education for kids who do not profit from this type of social and cultural wealth at home. But let s dive into the details.

The boy and the aliens (I ll be mostly transribing the interview, which was short, and which I find difficult to sum up because some of the questions are written in a way to encourage the kids to tell a story, and this particular kid had a thing going on with aliens.) He s a 13 year old boy living in the US. He has his own computer, which technically belongs to his school but can be used by him freely and he can also take it home. He s the first kid saying he s reading the news on the internet; he does not actually use social media, besides sometimes watching TikTok. When asked: Imagine that aliens land and come to you and say: We ve heard about this internet thing you all talk about, what is it? What do you tell them? he replied:
Well, I mean they re aliens, so I don t know if I wanna tell them much.
(Parents laughing in the background.) Let s assume they re friendly aliens.
Well, I would say you can look anything up and play different games. And there are alien games. But mostly the enemies are aliens which you might be a little offended by. And you can get work done, if you needed to spy on humans. There s cameras, you can film yourself, yeah. And you can text people and call people who are far away
And what would be in a drawing that would explain the internet? Google, an alien using Twitch, Google search results, and the interface of an IM software on an iPhone drawn by a 13 year old boy And here s what he explains about his drawing:
First, I would draw what I see when you open a new tab, Google.
On the right side of the drawing we see something like Twitch.
I don t wanna offend the aliens, but you can film yourself playing a game, so here is the alien and he s playing a game.
And then you can ask questions like: How did aliens come to the Earth? And the answer will be here (below). And there ll be different websites that you can click on.
And you can also look up Who won the alien contest? And that would be Usmushgagu, and that guy won the alien contest.
Do you think the information about alien intergalactic football is already on the internet?
Yeah! That s how fast the internet is.
On the bottom of the drawing we see an iPhone and an instant messaging software.
There s also a device called an iPhone and with it you can text your friends. So here s the alien asking: How was ur day? and the friend might answer IDK [I don t know].
Imagine that a wise and friendly dragon could teach you one thing about the internet that you ve always wanted to know. What would you ask the dragon to teach you about?
Is there a way you don t have to pay for any channels or subscriptions and you can get through any firewall?
Imagine you could make the internet better for everyone. What would you do first?
Well you wouldn t have to pay for it [paywalls].
Can you describe what happens between your device and a website when you visit a website?
Well, it takes 0.025 seconds. [ ] It s connecting.
Wow, that s indeed fast! We were not able to obtain more details about what is that fast thing that s happening exactly

The software engineer s kid This kid identifies as neither boy nor girl, is 10 years old and lives in Germany. Their father works as a software engineer, or in the words of the child:
My dad knows everything.
The kid has a laptop and a mobile phone, both with parental control they don t think that the controlling is fair. This kid uses the internet foremostly for listening to music and watching prank channels on Youtube but also to work with Purple Mash (a teaching platform for the computing curriculum used at their school), finding 3d printing models (that they ask their father to print with them because they did not manage to use the printer by themselves yet). Interestingly, and very differently from the non-tech-parent kids, this kid insists on using Firefox and Signal - the latter is not only used by their dad to tell them to come downstairs for dinner, but also to call their grandmother. This kid also shops online, with the help of the father who does the actual shopping for them using money that the kid earned by reading books. If you would need to explain to an alien who has landed on Earth what the internet is, what would you tell them?
The internet is something where you search, for example, you can look for music. You can also watch videos from around the world, and you can program stuff.
Like most of the kids interviewed, this kid uses the internet mostly for media consumption, but with the difference that they also engage with technology by way of programming using Purple Mash. drawing of the internet by a 10 year old showing a Youtube prank channel, an external device trackpad, and headphones In their drawing we see a Youtube prank channel on a screen, an external trackpad on the right (likely it s not a touch screen), and headphones. Notice how there is no keyboard, or maybe it s folded away. If you could ask a nice and friendly dragon anything you d like to learn about the internet, what would it be?
How do I shutdown my dad s computer forever?
And what is it that he would do to improve the internet for everyone? Contrary to the kid living in the US, they think that
It takes too much time to load stuff!
I wonder if this kid experiences the internet as being slow because they use the mobile network or because their connection somehow gets throttled as a way to control media consumption, or if the German internet infrastructure is just so much worse in certain regions If you could improve the internet for everyone, what would you do first? I d make a new Firefox app that loads the internet much faster.

The software engineer s daughter This girl is only 8 years old, she hates unicorns, and her dad is also a software engineer. She uses a smartphone, controlled by her parents. My impression of the interview is that at this age, kids slightly mix up the internet with the devices that they use to access the internet. drawing of the internet by an 8 year old girl, Showing Google and the interface to call and text someone In her drawing, we see again Google - it s clearly everywhere - and also the interfaces for calling and texting someone. To explain what the internet is, besides the fact that one can use it for calling and listening to music, she says:
[The internet] is something that you can [use to] see someone who is far away, so that you don t need to take time to get to them.
Now, that s a great explanation, the internet providing the possibility for communication over a distance :) If she could ask a friendly dragon something she always wanted to know, she d ask how to make her phone come alive:
that it can talk to you, that it can see you, that it can smile and has eyes. It s like a new family member, you can talk to it.
Sounds a bit like Siri, Alexa, or Furby, doesn t it? If you could improve the internet for everyone, what would you do first? She d have the phone be able to decide over her free time, her phone time. That would make the world better, not for the kids, but certainly for the parents.

The antifascist kid This German boy s dad has a background in electrotechnical engineering. He s 10 years old and he told me he s using the internet a lot for searching things for example about his passion: the firefighters. For him, the internet is:
An invisible world. A virtual world. But there s also the darknet.
He told me he always watches that German show on public TV for kids that explains stuff: Checker Tobi. (In 2014, Checker Tobi actually produced an episode about the internet, which I d criticize for having only male characters, except for one female character: a secretary Google, a nice and friendly woman guiding the way through the huge library that s the internet ) This kid was the only one interviewed who managed to actually explain something about the internet, or rather about the hypertextual structure of the web. When I asked him to draw the internet, he made a drawing of a pin board. He explained:
Many items are attached to the pin board, and on the top left corner there s a computer, for example with Youtube and one can navigate like that between all the items, and start again from the beginning when done.
hypertext structure representing the internet drawn by a kid When I asked if he knew what actually happens between the device and a website he visits, he put forth the hypothesis of the existence of some kind of
Waves, internet waves - all this stuff somehow needs to be transmitted.
What he d like to learn:
How to get into the darknet? How do you become a Whitehat? I ve heard these words on the internet, the internet makes me clever.
And what would he change on the internet if he could?
I want that right wing extreme stuff is not accessible anymore, or at least, that it rains turds ( Kackw rste ) whenever people watch such stuff. Or that people are always told: This video is scum.
I suspect that his father has been talking with him about these things, and maybe these are also subjects he heard about when listening to punk music (he told me he does), or browsing Youtube.

Future projects To me this has been pretty insightful. I might share some more internet drawings by adults in the future, which I think are also really interesting, as they show very different things depending on the age of the person. I ve been using the information gathered to work on a children s book which I hope to be able to share with you next year.

Russ Allbery: Review: The Afterward

Review: The Afterward, by E.K. Johnston
Publisher: Dutton Books
Copyright: February 2019
Printing: 2020
ISBN: 0-7352-3190-7
Format: Kindle
Pages: 339
The Afterward is a standalone young adult high fantasy with a substantial romance component. The title is not misspelled. Sir Erris and her six companions, matching the number of the new gods, were successful in their quest for the godsgem. They defeated the Old God and destroyed Him forever, freeing King Dorrenta from his ensorcellment, and returned in triumph to Cadrium to live happily ever after. Or so the story goes. Sir Erris and three of the companions are knights. Another companion is the best mage in the kingdom. Kalanthe Ironheart, who distracted the Old God at a critical moment and allowed Sir Erris to strike, is only an apprentice due to her age, but surely will become a great knight. And then there is Olsa Rhetsdaughter, the lowborn thief, now somewhat mockingly called Thief of the Realm for all the good that does her. The reward was enough for her to buy her freedom from the Thief's Court. It was not enough to pay for food after that, or enough for her to change her profession, and the Thief's Court no longer has any incentive to give her easy (or survivable) assignments. Kalanthe is in a considerably better position, but she still needs a good marriage. Her reward paid off half of her debt, which broadens her options, but she's still a debt-knight, liable for the full cost of her training once she reaches the age of nineteen. She's mostly made her peace with the decisions she made given her family's modest means, but marriages of that type are usually for heirs, and Kalanthe is not looking forward to bearing a child. Or, for that matter, sleeping with a man. Olsa and Kalanthe fell in love during the Quest. Given Kalanthe's debt and the way it must be paid, and her iron-willed determination to keep vows, neither of them expected their relationship to survive the end of the Quest. Both of them wish that it had. The hook is that this novel picks up after the epic fantasy quest is over and everyone went home. This is not an entirely correct synopsis; chapters of The Afterward alternate between "After" and "Before" (and one chapter delightfully titled "More or less the exact moment of"), and by the end of the book we get much of the story of the Quest. It's not told from the perspective of the lead heroes, though; it's told by following Kalanthe and Olsa, who would be firmly relegated to supporting characters in a typical high fantasy. And it's largely told through the lens of their romance. This is not the best fantasy novel I've read, but I had a fun time with it. I am now curious about the intended audience and marketing, though. It was published by a YA imprint, and both the ages of the main characters and the general theme of late teenagers trying to chart a course in an adult world match that niche. But it's also clearly intended for readers who have read enough epic fantasy quests that they will both be amused by the homage and not care that the story elides a lot of the typical details. Anyone who read David Eddings at an impressionable age will enjoy the way Johnston pokes gentle fun at The Belgariad (this book is dedicated to David and Leigh Eddings), but surely the typical reader of YA fantasy these days isn't also reading Eddings. I'm therefore not quite sure who this book was for, but apparently that group included me. Johnston thankfully is not on board with the less savory parts of Eddings's writing, as you might have guessed from the sapphic romance. There is no obnoxious gender essentialism here, although there do appear to be gender roles that I never quite figured out. Knights are referred to as sir, but all of the knights in this story are women. Men still seem to run a lot of things (kingdoms, estates, mage colleges), but apart from the mage, everyone on the Quest was female, and there seems to be an expectation that women go out into the world and have adventures while men stay home. I'm not sure if there was an underlying system that escaped me, or if Johnston just mixed things up for the hell of it. (If the latter, I approve.) This book does suffer a bit from addressing some current-day representation issues without managing to fold them naturally into the story or setting. One of the Quest knights is transgender, something that's revealed in a awkward couple of paragraphs and then never mentioned again. Two of the characters have a painfully earnest conversation about the word "bisexual," complete with a strained attempt at in-universe etymology. Racial diversity (Olsa is black, and Kalanthe is also not white) seemed to be handled a bit better, although I am not the reader to notice if the discussions of hair maintenance were similarly awkward. This is way better than no representation and default-white characters, to be clear, but it felt a bit shoehorned in at times and could have used some more polish. These are quibbles, though. Olsa was the heart of the book for me, and is exactly the sort of character I like to read about. Kalanthe is pure stubborn paladin, but I liked her more and more as the story continued. She provides a good counterbalance to Olsa's natural chaos. I do wish Olsa had more opportunities to show her own competence (she's not a very good thief, she's just the thief that Sir Erris happened to know), but the climax of the story was satisfying. My main grumble is that I badly wanted to dwell on the happily-ever-after for at least another chapter, ideally two. Johnston was done with the story before I was. The writing was serviceable but not great and there are some bits that I don't think would stand up to a strong poke, but the characters carried the story for me. Recommended if you'd like some sapphic romance and lightweight class analysis complicating your Eddings-style quest fantasy. Rating: 7 out of 10

28 December 2023

Antonio Terceiro: Debian CI: 10 years later

It was 2013, and I was on a break from work between Christmas and New Year of 2013. I had been working at Linaro for well over a year, on the LAVA project. I was living and breathing automated testing infrastructure, mostly for testing low-level components such as kernels and bootloaders, on real hardware. At this point I was also a Debian contributor for quite some years, and had become an official project members two years prior. Most of my involvement was in the Ruby team, where we were already consistently running upstream test suites during package builds. During that break, I put these two contexts together, and came to the conclusion that Debian needed a dedicated service that would test the contents of the Debian archive. I was aware of the existance of autopkgtest, and started working on a very simple service that would later become Debian CI. In January 2014, debci was initially announced on that month's Misc Developer News, and later uploaded to Debian. It's been continuously developed for the last 10 years, evolved from a single shell script running tests in a loop into a distributed system with 47 geographically-distributed machines as of writing this piece, became part of the official Debian release process gating migrations to testing, had 5 Summer of Code and Outrechy interns working on it, and processed beyond 40 million test runs. In there years, Debian CI has received contributions from a lot of people, but I would like to give special credits to the following:

Russ Allbery: Review: Nettle & Bone

Review: Nettle & Bone, by T. Kingfisher
Publisher: Tor
Copyright: 2022
ISBN: 1-250-24403-X
Format: Kindle
Pages: 242
Nettle & Bone is a standalone fantasy novel with fairy tale vibes. T. Kingfisher is a pen name for Ursula Vernon. As the book opens, Marra is giving herself a blood infection by wiring together dog bones out of a charnel pit. This is the second of three impossible tasks that she was given by the dust-wife. Completing all three will give her the tools to kill a prince. I am a little cautious of which T. Kingfisher books I read since she sometimes writes fantasy and sometimes writes horror and I don't get along with horror. This one seemed a bit horrific in the marketing, so I held off on reading it despite the Hugo nomination. It turns out to be just on the safe side of my horror tolerance, with only a couple of parts that I read a bit quickly. One of those is the opening, which I am happy to report does not set the tone for the rest of the book. Marra starts the story in a wasteland full of disease, madmen, and cannibals (who, in typical Ursula Vernon fashion, turn out to be nicer than the judgmental assholes outside of the blistered land). She doesn't stay there long. By chapter two, the story moves on to flashbacks explaining how Marra ended up there, alternating with further (and less horrific) steps in her quest to kill the prince of the Northern Kingdom. Marra is a princess of a small, relatively poor coastal kingdom with a good harbor and acquisitive neighbors. Her mother, the queen, has protected the kingdom through arranged marriage of her daughters to the prince of the Northern Kingdom, who rules it in all but name given the mental deterioration of his father the king. Marra's eldest sister Damia was first, but she died suddenly and mysteriously in a fall. (If you're thinking about the way women are injured by "accident," you have the right idea.) Kania, the middle sister, is next to marry; she lives, but not without cost. Meanwhile, Marra is sent off to a convent to ensure that there are no complicating potential heirs, and to keep her on hand as a spare. I won't spoil the entire backstory, but you do learn it all. Marra is a typical Kingfisher protagonist: a woman who is way out of her depth who persists with stubbornness, curiosity, and innate decency because what else is there to do? She accumulates the typical group of misfits and oddballs common in Kingfisher's quest fantasies, characters that in the Chosen One male fantasy would be supporting characters at best. The bone-wife is a delight; her chicken is even better. There are fairy godmothers and a goblin market and a tooth extraction that was one of the creepiest things I've read without actually being horror. It is, in short, a Kingfisher fantasy novel, with a touch more horror than average but not enough to push it out of the fantasy genre. I think my favorite part of this book was not the main quest. It was the flashback scenes set in the convent, where Marra has the space (and the mentorship) to develop her sense of self.
"We're a mystery religion," said the abbess, when she'd had a bit more wine than usual, "for people who have too much work to do to bother with mysteries. So we simply get along as best we can. Occasionally someone has a vision, but [the goddess] doesn't seem to want anything much, and so we try to return the favor."
If you have read any other Kingfisher novels, much of this will be familiar: the speculative asides, the dogged determination, the slightly askew nature of the world, the vibes-based world-building that feels more like a fairy tale than a carefully constructed magic system, and the sense that the main characters (and nearly all of the supporting characters) are average people trying to play the hands they were dealt as ethically as they can. You will know that the tentative and woman-initiated romance is coming as soon as the party meets the paladin type who is almost always the romantic interest in one of these books. The emotional tone of the book is a bit predictable for regular readers, but Ursula Vernon's brain is such a delightful place to spend some time that I don't mind.
Marra had not managed to be pale and willowy and consumptive at any point in eighteen years of life and did not think she could achieve it before she died.
Nettle & Bone won the Hugo for Best Novel in 2023. I'm not sure why this specific T. Kingfisher novel won and not any of the half-dozen earlier novels she's written in a similar style, but sure, I have no objections. I'm glad one of them won; they're all worth reading and hopefully that will help more people discover this delightful style of fantasy that doesn't feel like what anyone else is doing. Recommended, although be prepared for a few more horror touches than normal and a rather grim first chapter. Content warnings: domestic abuse. The dog... lives? Is equally as alive at the end of the book as it was at the end of the first chapter? The dog does not die; I'll just leave it at that. (Neither does the chicken.) Rating: 8 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

26 December 2023

Russ Allbery: Review: A Study in Honor

Review: A Study in Honor, by Claire O'Dell
Series: Janet Watson Chronicles #1
Publisher: Harper Voyager
Copyright: July 2018
ISBN: 0-06-269932-6
Format: Kindle
Pages: 295
A Study in Honor is a near-future science fiction novel by Claire O'Dell, a pen name for Beth Bernobich. You will see some assertions, including by the Lambda Literary Award judges, that it is a mystery novel. There is a mystery, but... well, more on that in a moment. Janet Watson was an Army surgeon in the Second US Civil War when New Confederacy troops overran the lines in Alton, Illinois. Watson lost her left arm to enemy fire. As this book opens, she is returning to Washington, D.C. with a medical discharge, PTSD, and a field replacement artificial arm scavenged from a dead soldier. It works, sort of, mostly, despite being mismatched to her arm and old in both technology and previous wear. It does not work well enough for her to resume her career as a surgeon. Watson's plan is to request a better artificial arm from the VA (the United States Department of Veterans Affairs, which among other things is responsible for the medical care of wounded veterans). That plan meets a wall of unyielding and uninterested bureaucracy. She has a pension, but it's barely enough for cheap lodging. A lifeline comes in the form of a chance encounter with a former assistant in the Army, who has a difficult friend looking to split the cost of an apartment. The name of that friend is Sara Holmes. At this point, you know what to expect. This is clearly one of the many respinnings of Arthur Conan Doyle. This time, the setting is in the future and Watson and Holmes are both black women, but the other elements of the setup are familiar: the immediate deduction that Watson came from the front, the shared rooms (2809 Q Street this time, sacrificing homage for the accuracy of a real address), Holmes's tendency to play an instrument (this time the piano), and even the title of this book, which is an obvious echo of the title of the first Holmes novel, A Study in Scarlet. Except that's not what you'll get. There are a lot of parallels and references here, but this is not a Holmes-style detective novel. First, it's only arguably a detective novel at all. There is a mystery, which starts with a patient Watson sees in her fallback job as a medical tech in the VA hospital and escalates to a physical attack, but that doesn't start until a third of the way into the book. It certainly is not solved through minute clues and leaps of deduction; instead, that part of the plot has the shape of a thriller rather than a classic mystery. There is a good argument that the thriller is the modern mystery novel, so I don't want to overstate my case, but I think someone who came to this book wanting a Doyle-style mystery would be disappointed. Second, the mystery is not the heart of this book. Watson is. She, like Doyle's Watson, is the first-person narrator, but she is far more present in the book. I have no idea how accurate O'Dell's portrayal of Watson's PTSD is, but it was certainly compelling and engrossing reading. Her fight for basic dignity and her rage at the surface respect and underlying disinterested hostility of the bureaucratic war machinery is what kept me turning the pages. The mystery plot is an outgrowth of that and felt more like a case study than the motivating thread of the plot. And third, Sara Holmes... well, I hesitate to say definitively that she's not Sherlock Holmes. There have been so many versions of Holmes over the years, even apart from the degree to which a black woman would necessarily not be like Doyle's character. But she did not remind me of Sherlock Holmes. She reminded me of a cross between James Bond and a high fae. This sounds like a criticism. It very much is not. I found this high elf spy character far more interesting than I have ever found Sherlock Holmes. But here again, if you came into this book hoping for a Holmes-style master detective, I fear you may be wrong-footed. The James Bond parts will be obvious when you get there and aren't the most interesting (and thankfully the misogyny is entirely absent). The part I found more fascinating is the way O'Dell sets Holmes apart by making her fae rather than insufferable. She projects effortless elegance, appears and disappears on a mysterious schedule of her own, thinks nothing of reading her roommate's diary, leaves meticulously arranged gifts, and even bargains with Watson for answers to precisely three questions. The reader does learn some mundane explanations for some of this behavior, but to be honest I found them somewhat of a letdown. Sara Holmes is at her best as a character when she tacks her own mysterious path through a rather grim world of exhausted war, penny-pinching bureaucracy, and despair, pursuing an unexplained agenda of her own while showing odd but unmistakable signs of friendship and care. This is not a romance, at least in this book. It is instead a slowly-developing friendship between two extremely different people, one that I thoroughly enjoyed. I do have a couple of caveats about this book. The first is that the future US in which it is set is almost pure Twitter doomcasting. Trump's election sparked a long slide into fascism, and when that was arrested by the election of a progressive candidate backed by a fragile coalition, Midwestern red states seceded to form the New Confederacy and start a second civil war that has dragged on for nearly eight years. It's a very specific mainstream liberal dystopian scenario that I've seen so many times it felt like a cliche even though I don't remember seeing it in a book before. This type of future projection of current fears is of course not new for science fiction; Cold War nuclear war novels are probably innumerable. But I had questions, such as how a sparsely-populated, largely non-industrial, and entirely landlocked set of breakaway states could maintain a war footing for eight years. Despite some hand-waving about covert support, those questions are not really answered here. The second problem is that the ending of this book kind of falls apart. The climax of the mystery investigation is unsatisfyingly straightforward, and the resulting revelation is a hoary cliche. Maybe I'm just complaining about the banality of evil, but if I'd been engrossed in this book for the thriller plot, I think I would have been annoyed. I wasn't, though; I was here for the characters, for Watson's PTSD and dogged determination, for Sara's strangeness, and particularly for the growing improbable friendship between two women with extremely different life experiences, emotions, and outlooks. That part was great, regardless of the ending. Do not pick this book up because you want a satisfying deductive mystery with bumbling police and a blizzard of apparently inconsequential clues. That is not at all what's happening here. But this was great on its own terms, and I will be reading the sequel shortly. Recommended, although if you are very online expect to do a bit of eye-rolling at the setting. Followed by The Hound of Justice, but the sequel is not required. This book reaches a satisfying conclusion of its own. Rating: 8 out of 10

25 December 2023

Sergio Talens-Oliag: GitLab CI/CD Tips: Automatic Versioning Using semantic-release

This post describes how I m using semantic-release on gitlab-ci to manage versioning automatically for different kinds of projects following a simple workflow (a develop branch where changes are added or merged to test new versions, a temporary release/#.#.# to generate the release candidate versions and a main branch where the final versions are published).

What is semantic-releaseIt is a Node.js application designed to manage project versioning information on Git Repositories using a Continuous integration system (in this post we will use gitlab-ci)

How does it workBy default semantic-release uses semver for versioning (release versions use the format MAJOR.MINOR.PATCH) and commit messages are parsed to determine the next version number to publish. If after analyzing the commits the version number has to be changed, the command updates the files we tell it to (i.e. the package.json file for nodejs projects and possibly a CHANGELOG.md file), creates a new commit with the changed files, creates a tag with the new version and pushes the changes to the repository. When running on a CI/CD system we usually generate the artifacts related to a release (a package, a container image, etc.) from the tag, as it includes the right version number and usually has passed all the required tests (it is a good idea to run the tests again in any case, as someone could create a tag manually or we could run extra jobs when building the final assets if they fail it is not a big issue anyway, numbers are cheap and infinite, so we can skip releases if needed).

Commit messages and versioningThe commit messages must follow a known format, the default module used to analyze them uses the angular git commit guidelines, but I prefer the conventional commits one, mainly because it s a lot easier to use when you want to update the MAJOR version. The commit message format used must be: 
<type>(optional scope): <description>
[optional body]
[optional footer(s)]
The system supports three types of branches: release, maintenance and pre-release, but for now I m not using maintenance ones. The branches I use and their types are:
  • main as release branch (final versions are published from there)
  • develop as pre release branch (used to publish development and testing versions with the format #.#.#-SNAPSHOT.#)
  • release/#.#.# as pre release branches (they are created from develop to publish release candidate versions with the format #.#.#-rc.# and once they are merged with main they are deleted)
On the release branch (main) the version number is updated as follows:
  1. The MAJOR number is incremented if a commit with a BREAKING CHANGE: footer or an exclamation (!) after the type/scope is found in the list of commits found since the last version change (it looks for tags on the same branch).
  2. The MINOR number is incremented if the MAJOR number is not going to be changed and there is a commit with type feat in the commits found since the last version change.
  3. The PATCH number is incremented if neither the MAJOR nor the MINOR numbers are going to be changed and there is a commit with type fix in the the commits found since the last version change.
On the pre release branches (develop and release/#.#.#) the version and pre release numbers are always calculated from the last published version available on the branch (i. e. if we published version 1.3.2 on main we need to have the commit with that tag on the develop or release/#.#.# branch to get right what will be the next version). The version number is updated as follows:
  1. The MAJOR number is incremented if a commit with a BREAKING CHANGE: footer or an exclamation (!) after the type/scope is found in the list of commits found since the last released version.In our example it was 1.3.2 and the version is updated to 2.0.0-SNAPSHOT.1 or 2.0.0-rc.1 depending on the branch.
  2. The MINOR number is incremented if the MAJOR number is not going to be changed and there is a commit with type feat in the commits found since the last released version.In our example the release was 1.3.2 and the version is updated to 1.4.0-SNAPSHOT.1 or 1.4.0-rc.1 depending on the branch.
  3. The PATCH number is incremented if neither the MAJOR nor the MINOR numbers are going to be changed and there is a commit with type fix in the the commits found since the last version change.In our example the release was 1.3.2 and the version is updated to 1.3.3-SNAPSHOT.1 or 1.3.3-rc.1 depending on the branch.
  4. The pre release number is incremented if the MAJOR, MINOR and PATCH numbers are not going to be changed but there is a commit that would otherwise update the version (i.e. a fix on 1.3.3-SNAPSHOT.1 will set the version to 1.3.3-SNAPSHOT.2, a fix or feat on 1.4.0-rc.1 will set the version to 1.4.0-rc.2 an so on).

How do we manage its configurationAlthough the system is designed to work with nodejs projects, it can be used with multiple programming languages and project types. For nodejs projects the usual place to put the configuration is the project s package.json, but I prefer to use the .releaserc file instead. As I use a common set of CI templates, instead of using a .releaserc on each project I generate it on the fly on the jobs that need it, replacing values related to the project type and the current branch on a template using the tmpl command (lately I use a branch of my own fork while I wait for some feedback from upstream, as you will see on the Dockerfile).

Container used to run itAs we run the command on a gitlab-ci job we use the image built from the following Dockerfile:
Dockerfile 
# Semantic release image
FROM golang:alpine AS tmpl-builder
#RUN go install github.com/krakozaure/tmpl@v0.4.0
RUN go install github.com/sto/tmpl@v0.4.0-sto.2
FROM node:lts-alpine
COPY --from=tmpl-builder /go/bin/tmpl /usr/local/bin/tmpl
RUN apk update &&\
  apk upgrade &&\
  apk add curl git jq openssh-keygen yq zip &&\
  npm install --location=global\
    conventional-changelog-conventionalcommits@6.1.0\
    @qiwi/multi-semantic-release@7.0.0\
    semantic-release@21.0.7\
    @semantic-release/changelog@6.0.3\
    semantic-release-export-data@1.0.1\
    @semantic-release/git@10.0.1\
    @semantic-release/gitlab@9.5.1\
    @semantic-release/release-notes-generator@11.0.4\
    semantic-release-replace-plugin@1.2.7\
    semver@7.5.4\
  &&\
  rm -rf /var/cache/apk/*
CMD ["/bin/sh"]

How and when is it executedThe job that runs semantic-release is executed when new commits are added to the develop, release/#.#.# or main branches (basically when something is merged or pushed) and after all tests have passed (we don t want to create a new version that does not compile or passes at least the unit tests). The job is something like the following: 
semantic_release:
  image: $SEMANTIC_RELEASE_IMAGE
  rules:
    - if: '$CI_COMMIT_BRANCH =~ /^(develop main release\/\d+.\d+.\d+)$/'
      when: always
  stage: release
  before_script:
    - echo "Loading scripts.sh"
    - . $ASSETS_DIR/scripts.sh
  script:
    - sr_gen_releaserc_json
    - git_push_setup
    - semantic-release
Where the SEMANTIC_RELEASE_IMAGE variable contains the URI of the image built using the Dockerfile above and the sr_gen_releaserc_json and git_push_setup are functions defined on the $ASSETS_DIR/scripts.sh file:
  • The sr_gen_releaserc_json function generates the .releaserc.json file using the tmpl command.
  • The git_push_setup function configures git to allow pushing changes to the repository with the semantic-release command, optionally signing them with a SSH key.

The sr_gen_releaserc_json functionThe code for the sr_gen_releaserc_json function is the following: 
sr_gen_releaserc_json()
 
  # Use nodejs as default project_type
  project_type="$ PROJECT_TYPE:-nodejs "
  # REGEX to match the rc_branch name
  rc_branch_regex='^release\/[0-9]\+\.[0-9]\+\.[0-9]\+$'
  # PATHS on the local ASSETS_DIR
  assets_dir="$ CI_PROJECT_DIR /$ ASSETS_DIR "
  sr_local_plugin="$ assets_dir /local-plugin.cjs"
  releaserc_tmpl="$ assets_dir /releaserc.json.tmpl"
  pipeline_runtime_values_yaml="/tmp/releaserc_values.yaml"
  pipeline_values_yaml="$ assets_dir /values_$ project_type _project.yaml"
  # Destination PATH
  releaserc_json=".releaserc.json"
  # Create an empty pipeline_values_yaml if missing
  test -f "$pipeline_values_yaml"   : >"$pipeline_values_yaml"
  # Create the pipeline_runtime_values_yaml file
  echo "branch: $ CI_COMMIT_BRANCH " >"$pipeline_runtime_values_yaml"
  echo "gitlab_url: $ CI_SERVER_URL " >"$pipeline_runtime_values_yaml"
  # Add the rc_branch name if we are on an rc_branch
  if [ "$(echo "$CI_COMMIT_BRANCH"   sed -ne "/$rc_branch_regex/ p ")" ]; then
    echo "rc_branch: $ CI_COMMIT_BRANCH " >>"$pipeline_runtime_values_yaml"
  elif [ "$(echo "$CI_MERGE_REQUEST_SOURCE_BRANCH_NAME"  
      sed -ne "/$rc_branch_regex/ p ")" ]; then
    echo "rc_branch: $ CI_MERGE_REQUEST_SOURCE_BRANCH_NAME " \
      >>"$pipeline_runtime_values_yaml"
  fi
  echo "sr_local_plugin: $ sr_local_plugin " >>"$pipeline_runtime_values_yaml"
  # Create the releaserc_json file
  tmpl -f "$pipeline_runtime_values_yaml" -f "$pipeline_values_yaml" \
    "$releaserc_tmpl"   jq . >"$releaserc_json"
  # Remove the pipeline_runtime_values_yaml file
  rm -f "$pipeline_runtime_values_yaml"
  # Print the releaserc_json file
  print_file_collapsed "$releaserc_json"
  # --*-- BEG: NOTE --*--
  # Rename the package.json to ignore it when calling semantic release.
  # The idea is that the local-plugin renames it back on the first step of the
  # semantic-release process.
  # --*-- END: NOTE --*--
  if [ -f "package.json" ]; then
    echo "Renaming 'package.json' to 'package.json_disabled'"
    mv "package.json" "package.json_disabled"
  fi
Almost all the variables used on the function are defined by gitlab except the ASSETS_DIR and PROJECT_TYPE; in the complete pipelines the ASSETS_DIR is defined on a common file included by all the pipelines and the project type is defined on the .gitlab-ci.yml file of each project. If you review the code you will see that the file processed by the tmpl command is named releaserc.json.tmpl, its contents are shown here: 
 
  "plugins": [
     - if .sr_local_plugin  
    "  .sr_local_plugin  ",
     - end  
    [
      "@semantic-release/commit-analyzer",
       
        "preset": "conventionalcommits",
        "releaseRules": [
            "breaking": true, "release": "major"  ,
            "revert": true, "release": "patch"  ,
            "type": "feat", "release": "minor"  ,
            "type": "fix", "release": "patch"  ,
            "type": "perf", "release": "patch"  
        ]
       
    ],
     - if .replacements  
    [
      "semantic-release-replace-plugin",
        "replacements":   .replacements   toJson    
    ],
     - end  
    "@semantic-release/release-notes-generator",
     - if eq .branch "main"  
    [
      "@semantic-release/changelog",
        "changelogFile": "CHANGELOG.md", "changelogTitle": "# Changelog"  
    ],
     - end  
    [
      "@semantic-release/git",
       
        "assets":   if .assets   .assets   toJson   else  []  end  ,
        "message": "ci(release): v$ nextRelease.version \n\n$ nextRelease.notes "
       
    ],
    [
      "@semantic-release/gitlab",
        "gitlabUrl": "  .gitlab_url  ", "successComment": false  
    ]
  ],
  "branches": [
      "name": "develop", "prerelease": "SNAPSHOT"  ,
     - if .rc_branch  
      "name": "  .rc_branch  ", "prerelease": "rc"  ,
     - end  
    "main"
  ]
The values used to process the template are defined on a file built on the fly (releaserc_values.yaml) that includes the following keys and values:
  • branch: the name of the current branch
  • gitlab_url: the URL of the gitlab server (the value is taken from the CI_SERVER_URL variable)
  • rc_branch: the name of the current rc branch; we only set the value if we are processing one because semantic-release only allows one branch to match the rc prefix and if we use a wildcard (i.e. release/*) but the users keep more than one release/#.#.# branch open at the same time the calls to semantic-release will fail for sure.
  • sr_local_plugin: the path to the local plugin we use (shown later)
The template also uses a values_$ project_type _project.yaml file that includes settings specific to the project type, the one for nodejs is as follows: 
replacements:
  - files:
      - "package.json"
    from: "\"version\": \".*\""
    to: "\"version\": \"$ nextRelease.version \""
assets:
  - "CHANGELOG.md"
  - "package.json"
The replacements section is used to update the version field on the relevant files of the project (in our case the package.json file) and the assets section includes the files that will be committed to the repository when the release is published (looking at the template you can see that the CHANGELOG.md is only updated for the main branch, we do it this way because if we update the file on other branches it creates a merge nightmare and we are only interested on it for released versions anyway). The local plugin adds code to rename the package.json_disabled file to package.json if present and prints the last and next versions on the logs with a format that can be easily parsed using sed:
local-plugin.cjs 
// Minimal plugin to:
// - rename the package.json_disabled file to package.json if present
// - log the semantic-release last & next versions
function verifyConditions(pluginConfig, context)  
  var fs = require('fs');
  if (fs.existsSync('package.json_disabled'))  
    fs.renameSync('package.json_disabled', 'package.json');
    context.logger.log( verifyConditions: renamed 'package.json_disabled' to 'package.json' );
   
 
function analyzeCommits(pluginConfig, context)  
  if (context.lastRelease && context.lastRelease.version)  
    context.logger.log( analyzeCommits: LAST_VERSION=$ context.lastRelease.version  );
   
 
function verifyRelease(pluginConfig, context)  
  if (context.nextRelease && context.nextRelease.version)  
    context.logger.log( verifyRelease: NEXT_VERSION=$ context.nextRelease.version  );
   
 
module.exports =  
  verifyConditions,
  analyzeCommits,
  verifyRelease

The git_push_setup functionThe code for the git_push_setup function is the following: 
git_push_setup()
 
  # Update global credentials to allow git clone & push for all the group repos
  git config --global credential.helper store
  cat >"$HOME/.git-credentials" <<EOF
https://fake-user:$ GITLAB_REPOSITORY_TOKEN @gitlab.com
EOF
  # Define user name, mail and signing key for semantic-release
  user_name="$SR_USER_NAME"
  user_email="$SR_USER_EMAIL"
  ssh_signing_key="$SSH_SIGNING_KEY"
  # Export git user variables
  export GIT_AUTHOR_NAME="$user_name"
  export GIT_AUTHOR_EMAIL="$user_email"
  export GIT_COMMITTER_NAME="$user_name"
  export GIT_COMMITTER_EMAIL="$user_email"
  # Sign commits with ssh if there is a SSH_SIGNING_KEY variable
  if [ "$ssh_signing_key" ]; then
    echo "Configuring GIT to sign commits with SSH"
    ssh_keyfile="/tmp/.ssh-id"
    : >"$ssh_keyfile"
    chmod 0400 "$ssh_keyfile"
    echo "$ssh_signing_key"   tr -d '\r' >"$ssh_keyfile"
    git config gpg.format ssh
    git config user.signingkey "$ssh_keyfile"
    git config commit.gpgsign true
  fi
The function assumes that the GITLAB_REPOSITORY_TOKEN variable (set on the CI/CD variables section of the project or group we want) contains a token with read_repository and write_repository permissions on all the projects we are going to use this function. The SR_USER_NAME and SR_USER_EMAIL variables can be defined on a common file or the CI/CD variables section of the project or group we want to work with and the script assumes that the optional SSH_SIGNING_KEY is exported as a CI/CD default value of type variable (that is why the keyfile is created on the fly) and git is configured to use it if the variable is not empty.
Warning: Keep in mind that the variables GITLAB_REPOSITORY_TOKEN and SSH_SIGNING_KEY contain secrets, so probably is a good idea to make them protected (if you do that you have to make the develop, main and release/* branches protected too).
Warning: The semantic-release user has to be able to push to all the projects on those protected branches, it is a good idea to create a dedicated user and add it as a MAINTAINER for the projects we want (the MAINTAINERS need to be able to push to the branches), or, if you are using a Gitlab with a Premium license you can use the api to allow the semantic-release user to push to the protected branches without allowing it for any other user.

The semantic-release commandOnce we have the .releaserc file and the git configuration ready we run the semantic-release command. If the branch we are working with has one or more commits that will increment the version, the tool does the following (note that the steps are described are the ones executed if we use the configuration we have generated):
  1. It detects the commits that will increment the version and calculates the next version number.
  2. Generates the release notes for the version.
  3. Applies the replacements defined on the configuration (in our example updates the version field on the package.json file).
  4. Updates the CHANGELOG.md file adding the release notes if we are going to publish the file (when we are on the main branch).
  5. Creates a commit if all or some of the files listed on the assets key have changed and uses the commit message we have defined, replacing the variables for their current values.
  6. Creates a tag with the new version number and the release notes.
  7. As we are using the gitlab plugin after tagging it also creates a release on the project with the tag name and the release notes.

Notes about the git workflows and merges between branchesIt is very important to remember that semantic-release looks at the commits of a given branch when calculating the next version to publish, that has two important implications:
  1. On pre release branches we need to have the commit that includes the tag with the released version, if we don t have it the next version is not calculated correctly.
  2. It is a bad idea to squash commits when merging a branch to another one, if we do that we will lose the information semantic-release needs to calculate the next version and even if we use the right prefix for the squashed commit (fix, feat, ) we miss all the messages that would otherwise go to the CHANGELOG.md file.
To make sure that we have the right commits on the pre release branches we should merge the main branch changes into the develop one after each release tag is created; in my pipelines the fist job that processes a release tag creates a branch from the tag and an MR to merge it to develop. The important thing about that MR is that is must not be squashed, if we do that the tag commit will probably be lost, so we need to be careful. To merge the changes directly we can run the following code: 
# Set the SR_TAG variable to the tag you want to process
SR_TAG="v1.3.2"
# Fetch all the changes
git fetch --all --prune
# Switch to the main branch
git switch main
# Pull all the changes
git pull
# Switch to the development branch
git switch develop
# Pull all the changes
git pull
# Create followup branch from tag
git switch -c "followup/$SR_TAG" "$SR_TAG"
# Change files manually & commit the changed files
git commit -a --untracked-files=no -m "ci(followup): $SR_TAG to develop"
# Switch to the development branch
git switch develop
# Merge the followup branch into the development one using the --no-ff option
git merge --no-ff "followup/$SR_TAG"
# Remove the followup branch
git branch -d "followup/$SR_TAG"
# Push the changes
git push
If we can t push directly to develop we can create a MR pushing the followup branch after committing the changes, but we have to make sure that we don t squash the commits when merging or it will not work as we want.

24 December 2023

Russ Allbery: Review: Liberty's Daughter

Review: Liberty's Daughter, by Naomi Kritzer
Publisher: Fairwood Press
Copyright: November 2023
ISBN: 1-958880-16-7
Format: Kindle
Pages: 257
Liberty's Daughter is a stand-alone near-future science fiction fix-up novel. The original stories were published in Fantasy and Science Fiction between 2012 and 2015. Beck Garrison lives on New Minerva (Min), one of a cluster of libertarian seasteads 220 nautical miles off the coast of Los Angeles. Her father brought her to Min when she was four, so it's the only life she knows. As this story opens, she's picked up a job for pocket change: finding very specific items that people want to buy. Since any new goods have to be shipped in and the seasteads have an ambiguous legal status, they don't get Amazon deliveries, but there are enough people (and enough tourists who bring high-value goods for trade) that someone probably has whatever someone else is looking for. Even sparkly high-heeled sandals size eight. Beck's father is high in the informal power structure of the seasteads for reasons that don't become apparent until very late in this book. Beck therefore has a comfortable, albeit cramped, life. The social protections, self-confidence, and feelings of invincibility that come with that wealth serve her well as a finder. After the current owner of the sandals bargains with her to find a person rather than an object, that privilege also lets her learn quite a lot before she starts getting into trouble. The political background of this novel is going to require some suspension of disbelief. The premise is that one of those harebrained libertarian schemes to form a freedom utopia has been successful enough to last for 49 years and attract 80,000 permanent residents. (It's a libertarian seastead so a lot of those residents are indentured slaves, as one does in libertarian philosophy. The number of people with shares, like Beck's father, is considerably smaller.) By the end of the book, Kritzer has offered some explanations for why the US would allow such a place to continue to exist, but the chances of the famously fractious con artists and incompetents involved in these types of endeavors creating something that survived internal power struggles for that long seem low. One has to roll with it for story reasons: Kritzer needs the population to be large enough for a plot, and the history to be long enough for Beck to exist as a character. The strength of this book is Beck, and specifically the fact that Beck is a second-generation teenager who grew up on the seastead. Unlike a lot of her age peers with their Cayman Islands vacations, she's never left and has no experience with life on land. She considers many things to be perfectly normal that are not at all normal to the reader and the various reader surrogates who show up over the course of the book. She also has the instinctive feel for seastead politics of the child of a prominent figure in a small town. And, most importantly, she has formed her own sense of morality and social structure that matches neither that of the reader nor that of her father. Liberty's Daughter is told in first-person by Beck. Judging the authenticity of Gen-Z thought processes is not one of my strengths, but Beck felt right to me. Her narration is dryly matter-of-fact, with only brief descriptions of her emotional reactions, but her personality shines in the occasional sarcasm and obstinacy. Kritzer has the teenage bafflement at the stupidity of adults down pat, as well as the tendency to jump head-first into ideas and make some decisions through sheer stubbornness. This is not one of those fix-up novels where the author has reworked the stories sufficiently that the original seams don't show. It is very episodic; compared to a typical novel of this length, there's more plot but less character growth. It's a good book when you want to be pulled into a stream of events that moves right along. This is not the book for deep philosophical examinations of the basis of a moral society, but it does have, around the edges, is the humans build human societies and develop elaborate social conventions and senses of belonging no matter how stupid the original philosophical foundations were. Even societies built on nasty exploitation can engender a sort of loyalty. Beck doesn't support the worst parts of her weird society, but she wants to fix it, not burn it to the ground. I thought there was a profound observation there. That brings me to my complaint: I hated the ending. Liberty's Daughter is in part Beck's fight for her own autonomy, both moral and financial, and the beginnings of an effort to turn her home into the sort of home she wants. By the end of the book, she's testing the limits of what she can accomplish, solidifying her own moral compass, and deciding how she wants to use the social position she inherited. It felt like the ending undermined all of that and treated her like a child. I know adolescence comes with those sorts of reversals, but I was still so mad. This is particularly annoying since I otherwise want to recommend this book. It's not ground-breaking, it's not that deep, but it was a thoroughly enjoyable day's worth of entertainment with a likable protagonist. Just don't read the last chapter, I guess? Or have more tolerance than I have for people treating sixteen-year-olds as if they're not old enough to make decisions. Content warnings: pandemic. Rating: 7 out of 10

23 December 2023

Russ Allbery: Review: Bookshops & Bonedust

Review: Bookshops & Bonedust, by Travis Baldree
Series: Legends & Lattes #2
Publisher: Tor
Copyright: 2023
ISBN: 1-250-88611-2
Format: Kindle
Pages: 337
Bookshops & Bonedust is a prequel to the cozy fantasy Legends & Lattes. You can read them in either order, although the epilogue of Bookshops & Bonedust spoils (somewhat guessable) plot developments in Legends & Lattes. Viv is a new member of the mercenary troop Rackam's Ravens and is still possessed of more enthusiasm than sense. As the story opens, she charges well ahead of her allies and nearly gets killed by a pike through the leg. She survives, but her leg needs time to heal and she is not up to the further pursuit of a necromancer. Rackam pays for a room and a doctor in the small seaside town of Murk and leaves her there to recuperate. The Ravens will pick her up when they come back through town, whenever that is. Viv is very quickly bored out of her skull. On a whim, and after some failures to find something else to occupy her, she tries a run-down local bookstore and promptly puts her foot through the boardwalk outside it. That's the start of an improbable friendship with the proprietor, a rattkin named Fern with a knack for book recommendations and a serious cash flow problem. Viv, being Viv, soon decides to make herself useful. The good side and bad side of this book are the same: it's essentially the same book as Legends & Lattes, but this time with a bookstore. There's a medieval sword and sorcery setting, a wide variety of humanoid species, a local business that needs love and attention (this time because it's failing instead of new), a lurking villain, an improbable store animal (this time a gryphlet that I found less interesting than the cat of the coffee shop), and a whole lot of found family. It turns out I was happy to read that story again, and there were some things I liked better in this version. I find bookstores more interesting than coffee shops, and although Viv and Fern go through a similar process of copying features of a modern bookstore, this felt less strained than watching Viv reinvent the precise equipment and menu of a modern coffee shop in a fantasy world. Also, Fern is an absolute delight, probably my favorite character in either of the books. I love the way that she uses book recommendations as a way of asking questions and guessing at answers about other people. As with the first book, Baldree's world-building is utterly unconcerned with trying to follow the faux-medieval conventions of either sword and sorcery or D&D-style role-playing games. On one hand, I like this; most of that so-called medievalism is nonsense anyway, and there's no reason why fantasy with D&D-style species diversity should be set in a medieval world. On the other hand, this world seems exactly like a US small town except the tavern also has rooms for rent, there are roving magical armies, and everyone fights with swords for some reason. It feels weirdly anachronistic, and I can't tell if that's because I've been brainwashed into thinking fantasy has to be medievaloid or if it's a true criticism of the book. I was reminded somewhat of reading Jack McDevitt's SF novels, which are supposedly set in the far future but are indistinguishable from 1980s suburbia except with flying cars. The other oddity with this book is that the reader of the series knows Viv isn't going to stay. This is the problem with writing a second iteration of this story as a prequel. I see why Baldree did it the story wouldn't have worked if Viv were already established but it casts a bit of a pall over the cheeriness of the story. Baldree to his credit confronts this directly, weaves it into the relationships, and salvages it a bit more in the epilogue, but it gave the story a sort of preemptive wistfulness that was at odds with how I wanted to read it. But, despite that, the strength of this book are the characters. Viv is a good person who helps where she can, which sounds like a simple thing but is so restful to read about. This book features her first meeting with the gnome Gallina, who is always a delight. There are delicious baked goods from a dwarf, a grumpy doctor, a grumpier city guard, and a whole cast of people who felt complicated and normal and essentially decent. I'm not sure the fantasy elements do anything for this book, or this series, other than marketing and the convenience of a few plot devices. Even though one character literally disappears into a satchel, it felt like Baldree could have written roughly the same story as a contemporary novel without a hint of genre. But that's not really a complaint, since the marketing works. I would not have read this series if it had been contemporary novels, and I thoroughly enjoyed it. It's a slice of life novel about kind and decent people for readers who are bored by contemporary settings and would rather read fantasy. Works for me. I'm hoping Baldree finds other stories, since I'm not sure I want to read this one several more times, but twice was not too much. If you liked Legends & Lattes and are thinking "how can I get more of that," here's the book for you. If you haven't read Legends & Lattes, I think I would recommend reading this one first. It does many of the same things, it's a bit more polished, and then you can read Viv's adventures in internal chronological order. Rating: 8 out of 10

22 December 2023

Gunnar Wolf: Pushing some reviews this way

Over roughly the last year and a half I have been participating as a reviewer in ACM s Computing Reviews, and have even been honored as a Featured Reviewer. Given I have long enjoyed reading friends reviews of their reading material (particularly, hats off to the very active Russ Allbery, who both beats all of my frequency expectations (I could never sustain the rythm he reads to!) and holds documented records for his >20 years as a book reader, with far more clarity and readability than I can aim for!), I decided to explicitly share my reviews via this blog, as the audience is somewhat congruent; I will also link here some reviews that were not approved for publication, clearly marking them so. I will probably work on wrangling my Jekyll site to display an (auto-)updated page and RSS feed for the reviews. In the meantime, the reviews I have published are:

Russ Allbery: Review: Wintersmith

Review: Wintersmith, by Terry Pratchett
Series: Discworld #35
Publisher: Clarion Books
Copyright: 2006
Printing: 2007
ISBN: 0-06-089033-9
Format: Mass market
Pages: 450
Wintersmith is the 35th Discworld novel and the 3rd Tiffany Aching novel. You could probably start here, since understanding the backstory isn't vital for following the plot, but I'm not sure why you would. Tiffany is now training with Miss Treason, a 113-year-old witch who is quite different in her approach from Miss Level, Tiffany's mentor in A Hat Full of Sky. Miss Level was the unassuming and constantly helpful glue that held the neighborhood together. Miss Treason is the judge; her neighbors are scared of her and proud of being scared of her, since that means they have a proper witch who can see into their heads and sort out their problems. On the surface, they're quite different; part of the story of this book is Tiffany learning to see the similarities. First, though, Miss Treason rushes Tiffany to a strange midnight Morris Dance, without any explanation. The Morris Dance usually celebrates the coming of spring and is at the center of a village party, so Tiffany is quite confused by seeing it danced on a dark and windy night in late autumn. But there is a hole in the dance where the Fool normally is, and Tiffany can't keep herself from joining it. This proves to be a mistake. That space was left for someone very different from Tiffany, and now she's entangled herself in deep magic that she doesn't understand. This is another Pratchett novel where the main storyline didn't do much for me. All the trouble stems from Miss Treason being maddeningly opaque, and while she did warn Tiffany, she did so in that way that guarantees a protagonist of a middle-grade novel will ignore. The Wintersmith is a boring, one-note quasi-villain, and the plot mainly revolves around elemental powers being dumber than a sack of hammers. The one thing I will say about the main plot is that the magic Tiffany danced into is entangled with courtship and romance, Tiffany turns thirteen over the course of this book, and yet this is not weird and uncomfortable reading the way it would be in the hands of many other authors. Pratchett has a keen eye for the age range that he's targeting. The first awareness that there is such a thing as romance that might be relevant to oneself pairs nicely with the Wintersmith's utter confusion at how Tiffany's intrusion unbalanced his dance. This is a very specific age and experience that I think a lot of authors would shy away from, particularly with a female protagonist, and I thought Pratchett handled it adroitly. I personally found the Wintersmith's awkward courting tedious and annoying, but that's more about me than about the book. As with A Hat Full of Sky, though, everything other than the main plot was great. It is becoming obvious how much Tiffany and Granny Weatherwax have in common, and that Granny Weatherwax recognizes this and is training Tiffany herself. This is high-quality coming-of-age material, not in the traditional fantasy sense of chosen ones and map explorations, but in the sense of slowly-developing empathy and understanding of people who think differently than you do. Tiffany, like Granny Weatherwax, has very little patience with nonsense, and her irritation with stupidity is one of her best characteristics. But she's learning how to blunt it long enough to pay attention, and to understand how people she doesn't like can still be the right people for specific situations. I particularly loved how Granny carries on with a feud at the same time that Tiffany is learning to let go of one. It's not a contradiction or hypocrisy; it's a sign that Tiffany is entitled to her judgments and feelings, but has to learn how to keep them in their place and not let them take over. One of the great things about the Tiffany Aching books is that the villages are also characters. We don't see that much of the individual people, but one of the things Tiffany is learning is how to see the interpersonal dynamics and patterns of village life. Somehow the feelings of irritation and exasperation fade once you understand people's motives and see more sides to their character. There is a lot more Nanny Ogg in this book than there has been in the last few, and that reminded me of how much I love her character. She has a completely different approach than Granny Weatherwax, but it's just as effective in different ways. She's also the perfect witch to have around when you've stumbled into a stylized love story that you don't want to be a part of, and yet find oddly fascinating. It says something about the skill of Pratchett's characterization that I could enjoy a book this much while having no interest in the main plot. The Witches have always been great characters, but somehow they're even better when seen through Tiffany's perspective. Good stuff; if you liked any of the other Tiffany Aching books, you will like this as well. Followed by Making Money in publication order. The next Tiffany Aching novel is I Shall Wear Midnight. Rating: 8 out of 10

20 December 2023

Ulrike Uhlig: How volunteer work in F/LOSS exacerbates pre-existing lines of oppression, and what that has to do with low diversity

This is a post I wrote in June 2022, but did not publish back then. After first publishing it in December 2023, a perfectionist insecure part of me unpublished it again. After receiving positive feedback, i slightly amended and republish it now. In this post, I talk about unpaid work in F/LOSS, taking on the example of hackathons, and why, in my opinion, the expectation of volunteer work is hurting diversity. Disclaimer: I don t have all the answers, only some ideas and questions.

Previous findings In 2006, the Flosspols survey searched to explain the role of gender in free/libre/open source software (F/LOSS) communities because an earlier [study] revealed a significant discrepancy in the proportion of men to women. It showed that just about 1.5% of F/LOSS community members were female at that time, compared with 28% in proprietary software (which is also a low number). Their key findings were, to name just a few:
  • that F/LOSS rewards the producing code rather than the producing software. It thereby puts most emphasis on a particular skill set. Other activities such as interface design or documentation are understood as less technical and therefore less prestigious.
  • The reliance on long hours of intensive computing in writing successful code means that men, who in general assume that time outside of waged labour is theirs , are freer to participate than women, who normally still assume a disproportionate amount of domestic responsibilities. Female F/LOSS participants, however, seem to be able to allocate a disproportionate larger share of their leisure time for their F/LOSS activities. This gives an indication that women who are not able to spend as much time on voluntary activities have difficulties to integrate into the community.
We also know from the 2016 Debian survey, published in 2021, that a majority of Debian contributors are employed, rather than being contractors, and rather than being students. Also, 95.5% of respondents to that study were men between the ages of 30 and 49, highly educated, with the largest groups coming from Germany, France, USA, and the UK. The study found that only 20% of the respondents were being paid to work on Debian. Half of these 20% estimate that the amount of work on Debian they are being paid for corresponds to less than 20% of the work they do there. On the other side, there are 14% of those who are being paid for Debian work who declared that 80-100% of the work they do in Debian is remunerated.

So, if a majority of people is not paid, why do they work on F/LOSS? Or: What are the incentives of free software? In 2021, Louis-Philippe V ronneau aka Pollo, who is not only a Debian Developer but also an economist, published his thesis What are the incentive structures of free software (The actual thesis was written in French). One very interesting finding Pollo pointed out is this one:
Indeed, while we have proven that there is a strong and significative correlation between the income and the participation in a free/libre software project, it is not possible for us to pronounce ourselves about the causality of this link.
In the French original text:
En effet, si nous avons prouv qu il existe une corr lation forte et significative entre le salaire et la participation un projet libre, il ne nous est pas possible de nous prononcer sur la causalit de ce lien.
Said differently, it is certain that there is a relationship between income and F/LOSS contribution, but it s unclear whether working on free/libre software ultimately helps finding a well paid job, or if having a well paid job is the cause enabling work on free/libre software. I would like to scratch this question a bit further, mostly relying on my own observations, experiences, and discussions with F/LOSS contributors.

Volunteer work is unpaid work We often hear of hackathons, hack weeks, or hackfests. I ve been at some such events myself, Tails organized one, the IETF regularly organizes hackathons, and last week (June 2022!) I saw an invitation for a hack week with the Torproject. This type of event generally last several days. While the people who organize these events are being paid by the organizations they work for, participants on the other hand are generally joining on a volunteer basis. Who can we expect to show up at this type of event under these circumstances as participants? To answer this question, I collected some ideas:
  • people who have an employer sponsoring their work
  • people who have a funder/grant sponsoring their work
  • people who have a high income and can take time off easily (in that regard, remember the Gender Pay Gap, women often earn less for the same work than men)
  • people who rely on family wealth (living off an inheritance, living on rights payments from a famous grandparent - I m not making these situations up, there are actual people in such financially favorable situations )
  • people who don t need much money because they don t have to pay rent or pay low rent (besides house owners that category includes people who live in squats or have social welfare paying for their rent, people who live with parents or caretakers)
  • people who don t need to do care work (for children, elderly family members, pets. Remember that most care work is still done by women.)
  • students who have financial support or are in a situation in which they do not yet need to generate a lot of income
  • people who otherwise have free time at their disposal
So, who, in your opinion, fits these unwritten requirements? Looking at this list, it s pretty clear to me why we d mostly find white men from the Global North, generally with higher education in hackathons and F/LOSS development. ( Great, they re a culture fit! ) Yes, there will also always be some people of marginalized groups who will attend such events because they expect to network, to find an internship, to find a better job in the future, or to add their participation to their curriculum. To me, this rings a bunch of alarm bells.

Low diversity in F/LOSS projects a mirror of the distribution of wealth I believe that the lack of diversity in F/LOSS is first of all a mirror of the distribution of wealth on a larger level. And by wealth I m referring to financial wealth as much as to social wealth in the sense of Bourdieu: Families of highly educated parents socially reproducing privilege by allowing their kids to attend better schools, supporting and guiding them in their choices of study and work, providing them with relations to internships acting as springboards into well paid jobs and so on. That said, we should ask ourselves as well:

Do F/LOSS projects exacerbate existing lines of oppression by relying on unpaid work? Let s look again at the causality question of Pollo s research (in my words):
It is unclear whether working on free/libre software ultimately helps finding a well paid job, or if having a well paid job is the cause enabling work on free/libre software.
Maybe we need to imagine this cause-effect relationship over time: as a student, without children and lots of free time, hopefully some money from the state or the family, people can spend time on F/LOSS, collect experience, earn recognition - and later find a well-paid job and make unpaid F/LOSS contributions into a hobby, cementing their status in the community, while at the same time generating a sense of well-being from working on the common good. This is a quite common scenario. As the Flosspols study revealed however, boys often get their own computer at the age of 14, while girls get one only at the age of 20. (These numbers might be slightly different now, and possibly many people don t own an actual laptop or desktop computer anymore, instead they own mobile devices which are not exactly inciting them to look behind the surface, take apart, learn, appropriate technology.) In any case, the above scenario does not allow for people who join F/LOSS later in life, eg. changing careers, to find their place. I believe that F/LOSS projects cannot expect to have more women, people of color, people from working class backgrounds, people from outside of Germany, France, USA, UK, Australia, and Canada on board as long as volunteer work is the status quo and waged labour an earned privilege.

Wait, are you criticizing all these wonderful people who sacrifice their free time to work towards common good? No, that s definitely not my intention, I m glad that F/LOSS exists, and the F/LOSS ecosystem has always represented a small utopia to me that is worth cherishing and nurturing. However, I think we still need to talk more about the lack of diversity, and investigate it further.

Some types of work are never being paid Besides free work at hacking events, let me also underline that a lot of work in F/LOSS is not considered payable work (yes, that s an oxymoron!). Which F/LOSS project for example, has ever paid translators a decent fee? Which project has ever considered that doing the social glue work, often done by women in the projects, is work that should be paid for? Which F/LOSS projects pay the people who do their Debian packaging rather than relying on yet another already well-paid white man who can afford doing this work for free all the while holding up how great the F/LOSS ecosystem is? And how many people on opensourcedesign jobs are looking to get their logo or website done for free? (Isn t that heart icon appealing to your altruistic empathy?) In my experience even F/LOSS projects which are trying to do the right thing by paying everyone the same amount of money per hour run into issues when it turns out that not all hours are equal and that some types of work do not qualify for remuneration at all or that the rules for the clocking of work are not universally applied in the same way by everyone.

Not every interaction should have a monetary value, but Some of you want to keep working without being paid, because that feels a bit like communism within capitalism, it makes you feel good to contribute to the greater good while not having the system determine your value over money. I hear you. I ve been there (and sometimes still am). But as long as we live in this system, even though we didn t choose to and maybe even despise it - communism is not about working for free, it s about getting paid equally and adequately. We may not think about it while under the age of 40 or 45, but working without adequate financial compensation, even half of the time, will ultimately result in not being able to care for oneself when sick, when old. And while this may not be an issue for people who inherit wealth, or have an otherwise safe economical background, eg. an academic salary, it is a huge problem and barrier for many people coming out of the working or service classes. (Oh and please, don t repeat the neoliberal lie that everyone can achieve whatever they aim for, if they just tried hard enough. French research shows that (in France) one has only 30% chance to become a class defector , and change social class upwards. But I managed to get out and move up, so everyone can! - well, if you believe that I m afraid you might be experiencing survivor bias.)

Not all bodies are equally able We should also be aware that not all of us can work with the same amount of energy either. There is yet another category of people who are excluded by the expectation of volunteer work, either because the waged labour they do already eats all of their energy, or because their bodies are not disposed to do that much work, for example because of mental health issues - such as depression-, or because of physical disabilities.

When organizing events relying on volunteer work please think about these things. Yes, you can tell people that they should ask their employer to pay them for attending a hackathon - but, as I ve hopefully shown, that would not do it for many people, especially newcomers. Instead, you could propose a fund to make it possible that people who would not normally attend can attend. DebConf is a good example for having done this for many years.

Conclusively I would like to urge free software projects that have a budget and directly pay some people from it to map where they rely on volunteer work and how this hurts diversity in their project. How do you or your project exacerbate pre-existing lines of oppression by granting or not granting monetary value to certain types of work? What is it that you take for granted? As always, I m curious about your feedback!

Worth a read These ideas are far from being new. Ashe Dryden s well-researched post The ethics of unpaid labor and the OSS community dates back to 2013 and is as important as it was ten years ago.

Ryan Kavanagh: Battery charge start and stop threshold on OpenBSD

I often use my laptops as portable desktops: they are plugged into AC power and an external monitor/keyboard 95% of time. Unfortunately, continuous charging is hard on the battery. To mitigate this, ThinkPads have customizable start and stop charging thresholds, such that the battery will only start charging if its level falls below the start threshold, and it will stop charging as soon as it reaches the stop threshold. Suggested thresholds from Lenovo s battery team can be found in this comment. You can set these thresholds on Linux using tlp-stat(8), and you can make the values persist across reboots by setting START_CHARGE_THRESH_BAT0 and STOP_CHARGE_THERSH_BAT0 in /etc/tlp.conf. I recently installed OpenBSD on my work ThinkPad, but struggled to find any information on how to set the thresholds under OpenBSD. After only finding a dead-end thread from 2021 on misc@, I started digging around on how to implement it myself. The acpithinkpad and acpibat drivers looked promising, and a bit of Google-fu lead me to the following small announcement in the OpenBSD 7.4 release notes:
New sysctl(2) nodes for battery management, hw.battery.charge*. Support them with acpithinkpad(4) and aplsmc(4).
Lo and behold, setting the start and stop threshold in OpenBSD is simply a matter of setting hw.battery.chargestart and hw.battery.chargestop with sysctl. The documentation was not committed in time for the 7.4 release, but you can read it in -CURRENT s sysctl(2). I personally set the following values in /etc/sysctl.conf: 
hw.battery.chargestart=40
hw.battery.chargestop=60

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.

Next.

Previous.