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7 November 2023

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

MPC Color Pipeline: After Blending (Per CRTC)

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

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

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

Others

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

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

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

5 November 2023

Thorsten Alteholz: My Debian Activities in October 2023

FTP master This month I accepted 361 and rejected 34 packages. The overall number of packages that got accepted was 362. Debian LTS This was my hundred-twelfth month that I did some work for the Debian LTS initiative, started by Raphael Hertzog at Freexian. During my allocated time I uploaded: Unfortunately upstream still could not resolve whether the patch for CVE-2023-42118 of libspf2 is valid, so no progress happened here.
I also continued to work on bind9 and try to understand why some tests fail. Last but not least I did some days of frontdesk duties and took part in the LTS meeting. Debian ELTS This month was the sixty-third ELTS month. During my allocated time I uploaded: I also continued to work on bind9 and as with the version in LTS, I try to understand why some tests fail. Last but not least I did some days of frontdesk duties . Debian Printing This month I uploaded a new upstream version of: Within the context of preserving old printing packages, I adopted: If you know of any other package that is also needed and still maintained by the QA team, please tell me. I also uploaded new upstream version of packages or uploaded a package to fix one or the other issue: This work is generously funded by Freexian! Debian Mobcom This month I uploaded a package to fix one or the other issue: Other stuff This month I uploaded new upstream version of packages, did a source upload for the transition or uploaded it to fix one or the other issue:

3 November 2023

Scarlett Gately Moore: KDE: Big fixes for Snaps! Debian and KDE neon updates.

KDE Snap Marble
A big thank you goes to my parents this week for contributing to my survival fund. With that I was able to make a big push on fixing some outstanding issues on some of our snaps.
KDE neon: No major blowups this week. Worked out issues with kmail-account-wizard thanks to David R! This is now in the hands of upstream ( porting not complete ) Worked on more orange -> green packaging fixes. Debian: Fixed bug https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1054713 in squashfuse Thanks for stopping by. Please help fund my efforts! <noscript><a href="https://liberapay.com/sgmoore/donate"><img alt="Donate using Liberapay" src="https://liberapay.com/assets/widgets/donate.svg" /></a></noscript> Donate https://gofund.me/b8b69e54

1 November 2023

Dirk Eddelbuettel: RcppArmadillo 0.12.6.6.0 on CRAN: Bugfix, Thread Throttling

armadillo image Armadillo is a powerful and expressive C++ template library for linear algebra and scientific computing. It aims towards a good balance between speed and ease of use, has a syntax deliberately close to Matlab, and is useful for algorithm development directly in C++, or quick conversion of research code into production environments. RcppArmadillo integrates this library with the R environment and language and is widely used by (currently) 1110 other packages on CRAN, downloaded 31.2 million times (per the partial logs from the cloud mirrors of CRAN), and the CSDA paper (preprint / vignette) by Conrad and myself has been cited 563 times according to Google Scholar. This release brings upstream bugfix releases 12.6.5 (sparse matrix corner case) and 12.6.6 with an ARPACK correction. Conrad released it this this morning, I had been running reverse dependency checks anyway and knew we were in good shape so for once I did not await a full run against the now over 1100 (!!) packages using RcppArmadillo. This release also contains a change I prepared on Sunday and which helps with much-criticized (and rightly I may add) insistence by CRAN concerning throttling . The motivation is understandable: CRAN tests many packages at once on beefy servers and can ill afford tests going off and requesting numerous cores. But rather than providing a global setting at their end, CRAN insists that each package (!!) deals with this. The recent traffic on the helpful-as-ever r-pkg-devel mailing clearly shows that this confuses quite a few package developers. Some have admitted to simply turning examples and tests off: a net loss for all of us. Now, Armadillo defaults to using up to eight cores (which is enough to upset CRAN) when running with OpenMP (which is generally only on Linux for reasons I rather not get into ). With this release I expose a helper functions (from OpenMP) to limit this. I also set up an example package and repo RcppArmadilloOpenMPEx detailing this, and added a demonstration of how to use the new throttlers to the fastLm example. I hope this proves useful to users of the package. The set of changes since the last CRAN release follows.

Changes in RcppArmadillo version 0.12.6.6.0 (2023-10-31)
  • Upgraded to Armadillo release 12.6.6 (Cortisol Retox)
    • Fix eigs_sym(), eigs_gen() and svds() to generate deterministic results in ARPACK mode
  • Add helper functions to set and get the number of OpenMP threads
  • Store initial thread count at package load and use in thread-throttling helper (and resetter) suitable for CRAN constraints

Changes in RcppArmadillo version 0.12.6.5.0 (2023-10-14)
  • Upgraded to Armadillo release 12.6.5 (Cortisol Retox)
    • Fix for corner-case bug in handling sparse matrices with no non-zero elements

Courtesy of my CRANberries, there is a diffstat report relative to previous release. More detailed information is on the RcppArmadillo page. Questions, comments etc should go to the rcpp-devel mailing list off the Rcpp R-Forge page. If you like this or other open-source work I do, you can sponsor me at GitHub.

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

31 October 2023

Iustin Pop: Raspberry PI OS: upgrading and cross-grading

One of the downsides of running Raspberry PI OS is the fact that - not having the resources of pure Debian - upgrades are not recommended, and cross-grades (migrating between armhf and arm64) is not even mentioned. Is this really true? It is, after all a Debian-based system, so it should in theory be doable. Let s try!

Upgrading The recently announced release based on Debian Bookworm here says:
We have always said that for a major version upgrade, you should re-image your SD card and start again with a clean image. In the past, we have suggested procedures for updating an existing image to the new version, but always with the caveat that we do not recommend it, and you do this at your own risk. This time, because the changes to the underlying architecture are so significant, we are not suggesting any procedure for upgrading a Bullseye image to Bookworm; any attempt to do this will almost certainly end up with a non-booting desktop and data loss. The only way to get Bookworm is either to create an SD card using Raspberry Pi Imager, or to download and flash a Bookworm image from here with your tool of choice.
Which means, it s time to actually try it turns out it s actually trivial, if you use RPIs as headless servers. I had only three issues:
  • if using an initrd, the new initrd-building scripts/hooks are looking for some binaries in /usr/bin, and not in /bin; solution: install manually the usrmerge package, and then re-run dpkg --configure -a;
  • also if using an initrd, the scripts are looking for the kernel config file in /boot/config-$(uname -r), and the raspberry pi kernel package doesn t provide this; workaround: modprobe configs && zcat /proc/config.gz > /boot/config-$(uname -r);
  • and finally, on normal RPI systems, that don t use manual configurations of interfaces in /etc/network/interface, migrating from the previous dhcpcd to NetworkManager will break network connectivity, and require you to log in locally and fix things.
I expect most people to hit only the 3rd, and almost no-one to use initrd on raspberry pi. But, overall, aside from these two issues and a couple of cosmetic ones (login.defs being rewritten from scratch and showing a baffling diff, for example), it was easy. Is it worth doing? Definitely. Had no data loss, and no non-booting system.

Cross-grading (32 bit to 64 bit userland) This one is actually painful. Internet searches go from it s possible, I think to it s definitely not worth trying . Examples: Aside from these, there are a gazillion other posts about switching the kernel to 64 bit. And that s worth doing on its own, but it s only half the way. So, armed with two different systems - a RPI4 4GB and a RPI Zero W2 - I tried to do this. And while it can be done, it takes many hours - first system was about 6 hours, second the same, and a third RPI4 probably took ~3 hours only since I knew the problematic issues. So, what are the steps? Basically:
  • install devscripts, since you will need dget
  • enable new architecture in dpkg: dpkg --add-architecture arm64
  • switch over apt sources to include the 64 bit repos, which are different than the 32 bit ones (Raspberry PI OS did a migration here; normally a single repository has all architectures, of course)
  • downgrade all custom rpi packages/libraries to the standard bookworm/bullseye version, since dpkg won t usually allow a single library package to have different versions (I think it s possible to override, but I didn t bother)
  • install libc for the arm64 arch (this takes some effort, it s actually a set of 3-4 packages)
  • once the above is done, install whiptail:amd64 and rejoice at running a 64-bit binary!
  • then painfully go through sets of packages and migrate the set to arm64:
    • sometimes this work via apt, sometimes you ll need to use dget and dpkg -i
    • make sure you download both the armhf and arm64 versions before doing dpkg -i, since you ll need to rollback some installs
  • at one point, you ll be able to switch over dpkg and apt to arm64, at which point the default architecture flips over; from here, if you ve done it at the right moment, it becomes very easy; you ll probably need an apt install --fix-broken, though, at first
  • and then, finish by replacing all packages with arm64 versions
  • and then, dpkg --remove-architecture armhf, reboot, and profit!
But it s tears and blood to get to that point

Pain point 1: RPI custom versions of packages Since the 32bit armhf architecture is a bit weird - having many variations - it turns out that raspberry pi OS has many packages that are very slightly tweaked to disable a compilation flag or work around build/test failures, or whatnot. Since we talk here about 64-bit capable processors, almost none of these are needed, but they do make life harder since the 64 bit version doesn t have those overrides. So what is needed would be to say downgrade all armhf packages to the version in debian upstream repo , but I couldn t find the right apt pinning incantation to do that. So what I did was to remove the 32bit repos, then use apt-show-versions to see which packages have versions that are no longer in any repo, then downgrade them. There s a further, minor, complication that there were about 3-4 packages with same version but different hash (!), which simply needed apt install --reinstall, I think.

Pain point 2: architecture independent packages There is one very big issue with dpkg in all this story, and the one that makes things very problematic: while you can have a library package installed multiple times for different architectures, as the files live in different paths, a non-library package can only be installed once (usually). For binary packages (arch:any), that is fine. But architecture-independent packages (arch:all) are problematic since usually they depend on a binary package, but they always depend on the default architecture version! Hrmm, and I just realise I don t have logs from this, so I m only ~80% confident. But basically:
  • vim-solarized (arch:all) depends on vim (arch:any)
  • if you replace vim armhf with vim arm64, this will break vim-solarized, until the default architecture becomes arm64
So you need to keep track of which packages apt will de-install, for later re-installation. It is possible that Multi-Arch: foreign solves this, per the debian wiki which says:
Note that even though Architecture: all and Multi-Arch: foreign may look like similar concepts, they are not. The former means that the same binary package can be installed on different architectures. Yet, after installation such packages are treated as if they were native architecture (by definition the architecture of the dpkg package) packages. Thus Architecture: all packages cannot satisfy dependencies from other architectures without being marked Multi-Arch foreign.
It also has warnings about how to properly use this. But, in general, not many packages have it, so it is a problem.

Pain point 3: remove + install vs overwrite It seems that depending on how the solver computes a solution, when migrating a package from 32 to 64 bit, it can choose either to:
  • overwrite in place the package (akin to dpkg -i)
  • remove + install later
The former is OK, the later is not. Or, actually, it might be that apt never can do this, for example (edited for brevity):
# apt install systemd:arm64 --no-install-recommends
The following packages will be REMOVED:
  systemd
The following NEW packages will be installed:
  systemd:arm64
0 upgraded, 1 newly installed, 1 to remove and 35 not upgraded.
Do you want to continue? [Y/n] y
dpkg: systemd: dependency problems, but removing anyway as you requested:
 systemd-sysv depends on systemd.
Removing systemd (247.3-7+deb11u2) ...
systemd is the active init system, please switch to another before removing systemd.
dpkg: error processing package systemd (--remove):
 installed systemd package pre-removal script subprocess returned error exit status 1
dpkg: too many errors, stopping
Errors were encountered while processing:
 systemd
Processing was halted because there were too many errors.
But at the same time, overwrite in place is all good - via dpkg -i from /var/cache/apt/archives. In this case it manifested via a prerm script, in other cases is manifests via dependencies that are no longer satisfied for packages that can t be removed, etc. etc. So you will have to resort to dpkg -i a lot.

Pain point 4: lib- packages that are not lib During the whole process, it is very tempting to just go ahead and install the corresponding arm64 package for all armhf lib package, in one go, since these can coexist. Well, this simple plan is complicated by the fact that some packages are named libfoo-bar, but are actual holding (e.g.) the bar binary for the libfoo package. Examples:
  • libmagic-mgc contains /usr/lib/file/magic.mgc, which conflicts between the 32 and 64 bit versions; of course, it s the exact same file, so this should be an arch:all package, but
  • libpam-modules-bin and liblockfile-bin actually contain binaries (per the -bin suffix)
It s possible to work around all this, but it changes a 1 minute:
# apt install $(dpkg -i   grep ^ii   awk ' print $2 ' grep :amrhf sed -e 's/:armhf/:arm64')
into a 10-20 minutes fight with packages (like most other steps).

Is it worth doing? Compared to the simple bullseye bookworm upgrade, I m not sure about this. The result? Yes, definitely, the system feels - weirdly - much more responsive, logged in over SSH. I guess the arm64 base architecture has some more efficient ops than the lowest denominator armhf , so to say (e.g. there was in the 32 bit version some rpi-custom package with string ops), and thus migrating to 64 bit makes more things faster , but this is subjective so it might be actually not true. But from the point of view of the effort? Unless you like to play with dpkg and apt, and understand how these work and break, I d rather say, migrate to ansible and automate the deployment. It s doable, sure, and by the third system, I got this nailed down pretty well, but it was a lot of time spent. The good aspect is that I did 3 migrations:
  • rpi zero w2: bullseye 32 bit to 64 bit, then bullseye to bookworm
  • rpi 4: bullseye to bookworm, then bookworm 32bit to 64 bit
  • same, again, for a more important system
And all three worked well and no data loss. But I m really glad I have this behind me, I probably wouldn t do a fourth system, even if forced And now, waiting for the RPI 5 to be available See you!

22 October 2023

Ravi Dwivedi: Software Freedom Day at sflc.in

Software Freedom Law Center, India, also known as sflc.in, organized an event to celebrate the Software Freedom Day on 30th September 2023. Me, Sahil, Contrapunctus and Suresh joined. The venue was at the SFLC India office in Delhi. The sflc.in office was on the second floor of what looked like someone s apartment:). I also met Chirag, Orendra, Surbhi and others. My plan was to have a stall on LibreOffice and Prav app to raise awareness about these projects. I didn t have QR code for downloading prav app printed already, so I asked the people at sflc.in if they can get it printed for me. They were very kind and helped me in getting a color printout for me. So, I got a stall in their main room. Surbhi was having an Inkscape stall next to mine and gave me company. People came and asked about the prav project and then I realized I was still too tired to explain the idea behind the prav project and about LibreOffice (after a long Kerala trip). We got a few prav app installs during the event, which is cool.
My stall. Photo credits: Tejaswini.
Sahil had Debian stall and contrapunctus had OpenStreetMap stall. After about an hour, Revolution OS was screened for all of us to watch, along with popcorn. The documentary gave an overview of history of Free Software Movement. The office had a kitchen where fresh chai was being made and served to us. The organizers ordered a lot of good snacks for us.
Snacks and tea at the front desk. CC-BY-SA 4.0 by Ravi Dwivedi.
I came out of the movie hall to take more tea and snacks from the front desk. I saw a beautiful painting was hanging at the wall opposite to the front desk and Tejaswini (from sflc.in) revealed that she had made it. The tea was really good as it was freshly made in the kitchen. After the movie, we played a game of pictionary. We were divided into two teams. The game goes as follows: A person from a team is selected and given a term related to freedom respecting software written on a piece of paper, but concealed from other participants. Then that person draws something on the board (no logo, no alphabets) without speaking. If the team from which the person belongs correctly guesses the term, the team gets one step ahead on the leader board. The team who reaches the finish line wins. I recall some fun pictionaries. Like, the one in the picture below seems far from the word Wireguard and even then someone from the team guessed that word. Our team won in the end \o/.
Pictionary drawing nowhere close to the intended word Wireguard :), which was guessed. Photo by Ravi Dwivedi, CC-BY-SA 4.0.
Then, we posed for a group picture. At the end, SFLC.in had a delicious cake in store for us. They had some merchandise - handbags, T-shirts, etc. which we could take if we donate some amount to SFLC.in. I bought a handbag with Ban Plastic, not Internet written on it in exchange for donation. I hope that gives people around me a powerful message :) .
Group photo. Photo credits: Tejaswini.
Tasty cake. CC-BY-SA 4.0 by Ravi Dwivedi.
Merchandise by sflc.in. CC-BY-SA 4.0 by Ravi Dwivedi.
All in all, a nice event by sflc.in :)

Ian Jackson: DigiSpark (ATTiny85) - Arduino, C, Rust, build systems

Recently I completed a small project, including an embedded microcontroller. For me, using the popular Arduino IDE, and C, was a mistake. The experience with Rust was better, but still very exciting, and not in a good way. Here follows the rant. Introduction In a recent project (I ll write about the purpose, and the hardware in another post) I chose to use a DigiSpark board. This is a small board with a USB-A tongue (but not a proper plug), and an ATTiny85 microcontroller, This chip has 8 pins and is quite small really, but it was plenty for my application. By choosing something popular, I hoped for convenient hardware, and an uncomplicated experience. Convenient hardware, I got. Arduino IDE The usual way to program these boards is via an IDE. I thought I d go with the flow and try that. I knew these were closely related to actual Arduinos and saw that the IDE package arduino was in Debian. But it turns out that the Debian package s version doesn t support the DigiSpark. (AFAICT from the list it offered me, I m not sure it supports any ATTiny85 board.) Also, disturbingly, its board manager seemed to be offering to install board support, suggesting it would download stuff from the internet and run it. That wouldn t be acceptable for my main laptop. I didn t expect to be doing much programming or debugging, and the project didn t have significant security requirements: the chip, in my circuit, has only a very narrow ability do anything to the real world, and no network connection of any kind. So I thought it would be tolerable to do the project on my low-security video laptop . That s the machine where I m prepared to say yes to installing random software off the internet. So I went to the upstream Arduino site and downloaded a tarball containing the Arduino IDE. After unpacking that in /opt it ran and produced a pointy-clicky IDE, as expected. I had already found a 3rd-party tutorial saying I needed to add a magic URL (from the DigiSpark s vendor) in the preferences. That indeed allowed it to download a whole pile of stuff. Compilers, bootloader clients, god knows what. However, my tiny test program didn t make it to the board. Half-buried in a too-small window was an error message about the board s bootloader ( Micronucleus ) being too new. The boards I had came pre-flashed with micronucleus 2.2. Which is hardly new, But even so the official Arduino IDE (or maybe the DigiSpark s board package?) still contains an old version. So now we have all the downsides of curl bash-ware, but we re lacking the it s up to date and it just works upsides. Further digging found some random forum posts which suggested simply downloading a newer micronucleus and manually stuffing it into the right place: one overwrites a specific file, in the middle the heaps of stuff that the Arduino IDE s board support downloader squirrels away in your home directory. (In my case, the home directory of the untrusted shared user on the video laptop,) So, whatever . I did that. And it worked! Having demo d my ability to run code on the board, I set about writing my program. Writing C again The programming language offered via the Arduino IDE is C. It s been a little while since I started a new thing in C. After having spent so much of the last several years writing Rust. C s primitiveness quickly started to grate, and the program couldn t easily be as DRY as I wanted (Don t Repeat Yourself, see Wilson et al, 2012, 4, p.6). But, I carried on; after all, this was going to be quite a small job. Soon enough I had a program that looked right and compiled. Before testing it in circuit, I wanted to do some QA. So I wrote a simulator harness that #included my Arduino source file, and provided imitations of the few Arduino library calls my program used. As an side advantage, I could build and run the simulation on my main machine, in my normal development environment (Emacs, make, etc.). The simulator runs confirmed the correct behaviour. (Perhaps there would have been some more faithful simulation tool, but the Arduino IDE didn t seem to offer it, and I wasn t inclined to go further down that kind of path.) So I got the video laptop out, and used the Arduino IDE to flash the program. It didn t run properly. It hung almost immediately. Some very ad-hoc debugging via led-blinking (like printf debugging, only much worse) convinced me that my problem was as follows: Arduino C has 16-bit ints. My test harness was on my 64-bit Linux machine. C was autoconverting things (when building for the micrcocontroller). The way the Arduino IDE ran the compiler didn t pass the warning options necessary to spot narrowing implicit conversions. Those warnings aren t the default in C in general because C compilers hate us all for compatibility reasons. I don t know why those warnings are not the default in the Arduino IDE, but my guess is that they didn t want to bother poor novice programmers with messages from the compiler explaining how their program is quite possibly wrong. After all, users don t like error messages so we shouldn t report errors. And novice programmers are especially fazed by error messages so it s better to just let them struggle themselves with the arcane mysteries of undefined behaviour in C? The Arduino IDE does offer a dropdown for compiler warnings . The default is None. Setting it to All didn t produce anything about my integer overflow bugs. And, the output was very hard to find anyway because the log window has a constant stream of strange messages from javax.jmdns, with hex DNS packet dumps. WTF. Other things that were vexing about the Arduino IDE: it has fairly fixed notions (which don t seem to be documented) about how your files and directories ought to be laid out, and magical machinery for finding things you put nearby its sketch (as it calls them) and sticking them in its ear, causing lossage. It has a tendency to become confused if you edit files under its feet (e.g. with git checkout). It wasn t really very suited to a workflow where principal development occurs elsewhere. And, important settings such as the project s clock speed, or even the target board, or the compiler warning settings to use weren t stored in the project directory along with the actual code. I didn t look too hard, but I presume they must be in a dotfile somewhere. This is madness. Apparently there is an Arduino CLI too. But I was already quite exasperated, and I didn t like the idea of going so far off the beaten path, when the whole point of using all this was to stay with popular tooling and share fate with others. (How do these others cope? I have no idea.) As for the integer overflow bug: I didn t seriously consider trying to figure out how to control in detail the C compiler options passed by the Arduino IDE. (Perhaps this is possible, but not really documented?) I did consider trying to run a cross-compiler myself from the command line, with appropriate warning options, but that would have involved providing (or stubbing, again) the Arduino/DigiSpark libraries (and bugs could easily lurk at that interface). Instead, I thought, if only I had written the thing in Rust . But that wasn t possible, was it? Does Rust even support this board? Rust on the DigiSpark I did a cursory web search and found a very useful blog post by Dylan Garrett. This encouraged me to think it might be a workable strategy. I looked at the instructions there. It seemed like I could run them via the privsep arrangement I use to protect myself when developing using upstream cargo packages from crates.io. I got surprisingly far surprisingly quickly. It did, rather startlingly, cause my rustup to download a random recent Nightly Rust, but I have six of those already for other Reasons. Very quickly I got the trinket LED blink example, referenced by Dylan s blog post, to compile. Manually copying the file to the video laptop allowed me to run the previously-downloaded micronucleus executable and successfully run the blink example on my board! I thought a more principled approach to the bootloader client might allow a more convenient workflow. I found the upstream Micronucleus git releases and tags, and had a look over its source code, release dates, etc. It seemed plausible, so I compiled v2.6 from source. That was a success: now I could build and install a Rust program onto my board, from the command line, on my main machine. No more pratting about with the video laptop. I had got further, more quickly, with Rust, than with the Arduino IDE, and the outcome and workflow was superior. So, basking in my success, I copied the directory containing the example into my own project, renamed it, and adjusted the path references. That didn t work. Now it didn t build. Even after I copied about .cargo/config.toml and rust-toolchain.toml it didn t build, producing a variety of exciting messages, depending what precisely I tried. I don t have detailed logs of my flailing: the instructions say to build it by cd ing to the subdirectory, and, given that what I was trying to do was to not follow those instructions, it didn t seem sensible to try to prepare a proper repro so I could file a ticket. I wasn t optimistic about investigating it more deeply myself: I have some experience of fighting cargo, and it s not usually fun. Looking at some of the build control files, things seemed quite complicated. Additionally, not all of the crates are on crates.io. I have no idea why not. So, I would need to supply local copies of them anyway. I decided to just git subtree add the avr-hal git tree. (That seemed better than the approach taken by the avr-hal project s cargo template, since that template involve a cargo dependency on a foreign git repository. Perhaps it would be possible to turn them into path dependencies, but given that I had evidence of file-location-sensitive behaviour, which I didn t feel like I wanted to spend time investigating, using that seems like it would possibly have invited more trouble. Also, I don t like package templates very much. They re a form of clone-and-hack: you end up stuck with whatever bugs or oddities exist in the version of the template which was current when you started.) Since I couldn t get things to build outside avr-hal, I edited the example, within avr-hal, to refer to my (one) program.rs file outside avr-hal, with a #[path] instruction. That s not pretty, but it worked. I also had to write a nasty shell script to work around the lack of good support in my nailing-cargo privsep tool for builds where cargo must be invoked in a deep subdirectory, and/or Cargo.lock isn t where it expects, and/or the target directory containing build products is in a weird place. It also has to filter the output from cargo to adjust the pathnames in the error messages. Otherwise, running both cd A; cargo build and cd B; cargo build from a Makefile produces confusing sets of error messages, some of which contain filenames relative to A and some relative to B, making it impossible for my Emacs to reliably find the right file. RIIR (Rewrite It In Rust) Having got my build tooling sorted out I could go back to my actual program. I translated the main program, and the simulator, from C to Rust, more or less line-by-line. I made the Rust version of the simulator produce the same output format as the C one. That let me check that the two programs had the same (simulated) behaviour. Which they did (after fixing a few glitches in the simulator log formatting). Emboldened, I flashed the Rust version of my program to the DigiSpark. It worked right away! RIIR had caused the bug to vanish. Of course, to rewrite the program in Rust, and get it to compile, it was necessary to be careful about the types of all the various integers, so that s not so surprising. Indeed, it was the point. I was then able to refactor the program to be a bit more natural and DRY, and improve some internal interfaces. Rust s greater power, compared to C, made those cleanups easier, so making them worthwhile. However, when doing real-world testing I found a weird problem: my timings were off. Measured, the real program was too fast by a factor of slightly more than 2. A bit of searching (and searching my memory) revealed the cause: I was using a board template for an Adafruit Trinket. The Trinket has a clock speed of 8MHz. But the DigiSpark runs at 16.5MHz. (This is discussed in a ticket against one of the C/C++ libraries supporting the ATTiny85 chip.) The Arduino IDE had offered me a choice of clock speeds. I have no idea how that dropdown menu took effect; I suspect it was adding prelude code to adjust the clock prescaler. But my attempts to mess with the CPU clock prescaler register by hand at the start of my Rust program didn t bear fruit. So instead, I adopted a bodge: since my code has (for code structure reasons, amongst others) only one place where it dealt with the underlying hardware s notion of time, I simply changed my delay function to adjust the passed-in delay values, compensating for the wrong clock speed. There was probably a more principled way. For example I could have (re)based my work on either of the two unmerged open MRs which added proper support for the DigiSpark board, rather than abusing the Adafruit Trinket definition. But, having a nearly-working setup, and an explanation for the behaviour, I preferred the narrower fix to reopening any cans of worms. An offer of help As will be obvious from this posting, I m not an expert in dev tools for embedded systems. Far from it. This area seems like quite a deep swamp, and I m probably not the person to help drain it. (Frankly, much of the improvement work ought to be done, and paid for, by hardware vendors.) But, as a full Member of the Debian Project, I have considerable gatekeeping authority there. I also have much experience of software packaging, build systems, and release management. If anyone wants to try to improve the situation with embedded tooling in Debian, and is willing to do the actual packaging work. I would be happy to advise, and to review and sponsor your contributions. An obvious candidate: it seems to me that micronucleus could easily be in Debian. Possibly a DigiSpark board definition could be provided to go with the arduino package. Unfortunately, IMO Debian s Rust packaging tooling and workflows are very poor, and the first of my suggestions for improvement wasn t well received. So if you need help with improving Rust packages in Debian, please talk to the Debian Rust Team yourself. Conclusions Embedded programming is still rather a mess and probably always will be. Embedded build systems can be bizarre. Documentation is scant. You re often expected to download board support packages full of mystery binaries, from the board vendor (or others). Dev tooling is maddening, especially if aimed at novice programmers. You want version control? Hermetic tracking of your project s build and install configuration? Actually to be told by the compiler when you write obvious bugs? You re way off the beaten track. As ever, Free Software is under-resourced and the maintainers are often busy, or (reasonably) have other things to do with their lives. All is not lost Rust can be a significantly better bet than C for embedded software: The Rust compiler will catch a good proportion of programming errors, and an experienced Rust programmer can arrange (by suitable internal architecture) to catch nearly all of them. When writing for a chip in the middle of some circuit, where debugging involves staring an LED or a multimeter, that s precisely what you want. Rust embedded dev tooling was, in this case, considerably better. Still quite chaotic and strange, and less mature, perhaps. But: significantly fewer mystery downloads, and significantly less crazy deviations from the language s normal build system. Overall, less bad software supply chain integrity. The ATTiny85 chip, and the DigiSpark board, served my hardware needs very well. (More about the hardware aspects of this project in a future posting.)

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20 October 2023

Freexian Collaborators: Debian Contributions: Freexian meetup, debusine updates, lpr/lpd in Debian, and more! (by Utkarsh Gupta, Stefano Rivera)

Contributing to Debian is part of Freexian s mission. This article covers the latest achievements of Freexian and their collaborators. All of this is made possible by organizations subscribing to our Long Term Support contracts and consulting services.

Freexian Meetup, by Stefano Rivera, Utkarsh Gupta, et al. During DebConf, Freexian organized a meetup for its collaborators and those interested in learning more about Freexian and its services. It was well received and many people interested in Freexian showed up. Some developers who were interested in contributing to LTS came to get more details about joining the project. And some prospective customers came to get to know us and ask questions. Sadly, the tragic loss of Abraham shook DebConf, both individually and structurally. The meetup got rescheduled to a small room without video coverage. With that, we still had a wholesome interaction and here s a quick picture from the meetup taken by Utkarsh (which is also why he s missing!).

Debusine, by Rapha l Hertzog, et al. Freexian has been investing into debusine for a while, but development speed is about to increase dramatically thanks to funding from SovereignTechFund.de. Rapha l laid out the 5 milestones of the funding contract, and filed the issues for the first milestone. Together with Enrico and Stefano, they established a workflow for the expanded team. Among the first steps of this milestone, Enrico started to work on a developer-friendly description of debusine that we can use when we reach out to the many Debian contributors that we will have to interact with. And Rapha l started the design work of the autopkgtest and lintian tasks, i.e. what s the interface to schedule such tasks, what behavior and what associated options do we support? At this point you might wonder what debusine is supposed to be let us try to answer this: Debusine manages scheduling and distribution of Debian-related build and QA tasks to a network of worker machines. It also manages the resulting artifacts and provides the results in an easy to consume way. We want to make it easy for Debian contributors to leverage all the great QA tools that Debian provides. We want to build the next generation of Debian s build infrastructure, one that will continue to reliably do what it already does, but that will also enable distribution-wide experiments, custom package repositories and custom workflows with advanced package reviews. If this all sounds interesting to you, don t hesitate to watch the project on salsa.debian.org and to contribute.

lpr/lpd in Debian, by Thorsten Alteholz During Debconf23, Till Kamppeter presented CPDB (Common Print Dialog Backend), a new way to handle print queues. After this talk it was discussed whether the old lpr/lpd based printing system could be abandoned in Debian or whether there is still demand for it. So Thorsten asked on the debian-devel email list whether anybody uses it. Oddly enough, these old packages are still useful:
  • Within a small network it is easier to distribute a printcap file, than to properly configure cups clients.
  • One of the biggest manufacturers of WLAN router and DSL boxes only supports raw queues when attaching an USB printer to their hardware. Admittedly the CPDB still has problems with such raw queues.
  • The Pharos printing system at MIT is still lpd-based.
As a result, the lpr/lpd stuff is not yet ready to be abandoned and Thorsten will adopt the relevant packages (or rather move them under the umbrella of the debian-printing team). Though it is not planned to develop new features, those packages should at least have a maintainer. This month Thorsten adopted rlpr, an utility for lpd printing without using /etc/printcap. The next one he is working on is lprng, a lpr/lpd printer spooling system. If you know of any other package that is also needed and still maintained by the QA team, please tell Thorsten.

/usr-merge, by Helmut Grohne Discussion about lifting the file move moratorium has been initiated with the CTTE and the release team. A formal lift is dependent on updating debootstrap in older suites though. A significant number of packages can automatically move their systemd unit files if dh_installsystemd and systemd.pc change their installation targets. Unfortunately, doing so makes some packages FTBFS and therefore patches have been filed. The analysis tool, dumat, has been enhanced to better understand which upgrade scenarios are considered supported to reduce false positive bug filings and gained a mode for local operation on a .changes file meant for inclusion in salsa-ci. The filing of bugs from dumat is still manual to improve the quality of reports. Since September, the moratorium has been lifted.

Miscellaneous contributions
  • Rapha l updated Django s backport in bullseye-backports to match the latest security release that was published in bookworm. Tracker.debian.org is still using that backport.
  • Helmut Grohne sent 13 patches for cross build failures.
  • Helmut Grohne performed a maintenance upload of debvm enabling its use in autopkgtests.
  • Helmut Grohne wrote an API-compatible reimplementation of autopkgtest-build-qemu. It is powered by mmdebstrap, therefore unprivileged, EFI-only and will soon be included in mmdebstrap.
  • Santiago continued the work regarding how to make it easier to (automatically) test reverse dependencies. An example of the ongoing work was presented during the Salsa CI BoF at DebConf 23.
    In fact, omniorb-dfsg test pipelines as the above were used for the omniorb-dfsg 4.3.0 transition, verifying how the reverse dependencies (tango, pytango and omnievents) were built and how their autopkgtest jobs run with the to-be-uploaded omniorb-dfsg new release.
  • Utkarsh and Stefano attended and helped run DebConf 23. Also continued winding up DebConf 22 accounting.
  • Anton Gladky did some science team uploads to fix RC bugs.

17 October 2023

Russ Allbery: Review: A Hat Full of Sky

Review: A Hat Full of Sky, by Terry Pratchett
Series: Discworld #32
Publisher: HarperTrophy
Copyright: 2004
Printing: 2005
ISBN: 0-06-058662-1
Format: Mass market
Pages: 407
A Hat Full of Sky is the 32nd Discworld novel and the second Tiffany Aching young adult novel. You should not start here, but you could start with The Wee Free Men. As with that book, some parts of the story carry more weight if you are already familiar with Granny Weatherwax. Tiffany is a witch, but she needs to be trained. This is normally done by apprenticeship, and in Tiffany's case it seemed wise to give her exposure to more types of witching. Thus, Tiffany, complete with new boots and a going-away present from the still-somewhat-annoying Roland, is off on an apprenticeship to the sensible Miss Level. (The new boots feel wrong and get swapped out for her concealed old boots at the first opportunity.) Unbeknownst to Tiffany, her precocious experiments with leaving her body as a convenient substitute for a mirror have attracted something very bad, something none of the witches are expecting. The Nac Mac Feegle know a hiver as soon as they feel it, but they have a new kelda now, and she's not sure she wants them racing off after their old kelda. Terry Pratchett is very good at a lot of things, but I don't think villains are one of his strengths. He manages an occasional memorable one (the Auditors, for example, at least before the whole chocolate thing), but I find most of them a bit boring. The hiver is one of the boring ones. It serves mostly as a concretized metaphor about the temptations of magical power, but those temptations felt so unlike the tendencies of Tiffany's personality that I didn't think the metaphor worked in the story. The interesting heart of this book to me is the conflict between Tiffany's impatience with nonsense and Miss Level's arguably excessive willingness to help everyone regardless of how demanding they get. There's something deeper in here about female socialization and how that interacts with Pratchett's conception of witches that got me thinking, although I don't think Pratchett landed the point with full force. Miss Level is clearly a good witch to her village and seems comfortable with how she lives her life, so perhaps they're not taking advantage of her, but she thoroughly slots herself into the helper role. If Tiffany attempted the same role, people would be taking advantage of her, because the role doesn't fit her. And yet, there's a lesson here she needs to learn about seeing other people as people, even if it wouldn't be healthy for her to move all the way to Miss Level's mindset. Tiffany is a precocious kid who is used to being underestimated, and who has reacted by becoming independent and somewhat judgmental. She's also had a taste of real magical power, which creates a risk of her getting too far into her own head. Miss Level is a fount of empathy and understanding for the normal people around her, which Tiffany resists and needed to learn. I think Granny Weatherwax is too much like Tiffany to teach her that. She also has no patience for fools, but she's older and wiser and knows Tiffany needs a push in that direction. Miss Level isn't a destination, but more of a counterbalance. That emotional journey, a conclusion that again focuses on the role of witches in questions of life and death, and Tiffany's fascinatingly spiky mutual respect with Granny Weatherwax were the best parts of this book for me. The middle section with the hiver was rather tedious and forgettable, and the Nac Mac Feegle were entertaining but not more than that. It felt like the story went in a few different directions and only some of them worked, in part because the villain intended to tie those pieces together was more of a force of nature than a piece of Tiffany's emotional puzzle. If the hiver had resonated with the darker parts of Tiffany's natural personality, the plot would have worked better. Pratchett was gesturing in that direction, but he never convinced me it was consistent with what we'd already seen of her. Like a lot of the Discworld novels, the good moments in A Hat Full of Sky are astonishing, but the plot is somewhat forgettable. It's still solidly entertaining, though, and if you enjoyed The Wee Free Men, I think this is slightly better. Followed by Going Postal in publication order. The next Tiffany Aching novel is Wintersmith. Rating: 8 out of 10

15 October 2023

Michael Ablassmeier: Testing system updates using libvirts checkpoint feature

If you want to test upgrades on virtual machines (running on libvit/qemu/kvm) these are usually the most common steps: As with recent versions, both libvirt and qemu have full support for dirty bitmaps (so called checkpoints). These checkpoints, once existent, will track changes to the block level layer and can be exported via NBD protocol. Usually one can create these checkpoints using virsh checkpoint-create[-as], with a proper xml description. Using the pull based model, the following is possible: The overlay image will only use the disk space for the blocks changed during upgrade: no need to create a full clone which may waste a lot of disk space. In order to simplify the first step, its possible to use virtnbdbackup for creating the required consistent checkpoint and export its data using a unix domain socket. Update: As alternative, ive just created a small utility called vircpt to create and export checkpoints. In my example im using a debian11 virtual machine with qemu guest agent configured:
# virsh list --all
 Id Name State 
 ------------------------------------------ 
 1 debian11_default running
Now let virtnbdbackup create an checkpoint, freeze the filesystems during creation and tell libvirt to provide us with a usable NBD server listening on an unix socket:
# virtnbdbackup -d debian11_default -o /tmp/foo -s
INFO lib common - printVersion [MainThread]: Version: 1.9.45 Arguments: ./virtnbdbackup -d debian11_default -o /tmp/foo -s
[..] 
INFO root virtnbdbackup - main [MainThread]: Local NBD Endpoint socket: [/var/tmp/virtnbdbackup.5727] 
INFO root virtnbdbackup - startBackupJob [MainThread]: Starting backup job.
INFO fs fs - freeze [MainThread]: Freezed [2] filesystems. 
INFO fs fs - thaw [MainThread]: Thawed [2] filesystems. 
INFO root virtnbdbackup - main [MainThread]: Started backup job for debugging, exiting.
We can now use nbdinfo to display some information about the NBD export:
# nbdinfo "nbd+unix:///vda?socket=/var/tmp/virtnbdbackup.5727" 
    protocol: newstyle-fixed without TLS, using structured packets 
    export="vda": 
    export-size: 137438953472 (128G) 
    content: 
        DOS/MBR boot sector uri: nbd+unix:///vda?socket=/var/tmp/virtnbdbackup.5727
And create a backing image that we can use to test an in-place upgrade:
# qemu-img create -F raw -b nbd+unix:///vda?socket=/var/tmp/virtnbdbackup.5727 -f qcow2 upgrade.qcow2
Now we have various ways for booting the image:
# qemu-system-x86_64 -hda upgrade.qcow2 -m 2500 --enable-kvm
image After performing the required tests within the virtual machine we can simply kill the active NBD backup job :
# virtnbdbackup -d debian11_default -o /tmp/foo -k
INFO lib common - printVersion [MainThread]: Version: 1.9.45 Arguments: ./virtnbdbackup -d debian11_default -o /tmp/foo -k 
[..]
INFO root virtnbdbackup - main [MainThread]: Stopping backup job
And remove the created qcow image:
# rm -f upgrade.qcow2

14 October 2023

Ravi Dwivedi: Kochi - Wayanad Trip in August-September 2023

A trip full of hitchhiking, beautiful places and welcoming locals.

Day 1: Arrival in Kochi Kochi is a city in the state of Kerala, India. This year s DebConf was to be held in Kochi from 3rd September to 17th of September, which I was planning to attend. My friend Suresh, who was planning to join, told me that 29th August 2023 will be Onam, a major festival of the state of Kerala. So, we planned a Kerala trip before the DebConf. We booked early morning flights for Kochi from Delhi and reached Kochi on 28th August. We had booked a hostel named Zostel in Ernakulam. During check-in, they asked me to fill a form which required signing in using a Google account. I told them I don t have a Google account and I don t want to create one either. The people at the front desk seemed receptive, so I went ahead with telling them the problems of such a sign-in being mandatory for check-in. Anyways, they only took a photo of my passport and let me check-in without a Google account. We stayed in a ten room dormitory, which allowed travellers of any gender. The dormitory room was air-conditioned, spacious, clean and beds were also comfortable. There were two bathrooms in the dormitory and they were clean. Plus, there was a separate dormitory room in the hostel exclusive for females. I noticed that that Zostel was not added in the OpenStreetMap and so, I added it :) . The hostel had a small canteen for tea and snacks, a common sitting area outside the dormitories, which had beds too. There was a separate silent room, suitable for people who want to work.
Dormitory room in Zostel Ernakulam, Kochi.
Beds in Zostel Ernakulam, Kochi.
We had lunch at a nearby restaurant and it was hard to find anything vegetarian for me. I bought some freshly made banana chips from the street and they were tasty. As far as I remember, I had a big glass of pineapple juice for lunch. Then I went to the Broadway market and bought some cardamom and cinnamon for home. I also went to a nearby supermarket and bought Matta brown rice for home. Then, I looked for a courier shop to send the things home but all of them were closed due to Onam festival. After returning to the Zostel, I overslept till 9 PM and in the meanwhile, Suresh planned with Saidut and Shwetank (who met us during our stay in Zostel) to go to a place in Fort Kochi for dinner. I suspected I will be disappointed by lack of vegetarian options as they were planning to have fish. I already had a restaurant in mind - Brindhavan restaurant (suggested by Anupa), which was a pure vegetarian restaurant. To reach there, I got off at Palarivattom metro station and started looking for an auto-rickshaw to get to the restaurant. I didn t get any for more than 5 minutes. Since that restaurant was not added to the OpenStreetMap, I didn t even know how far that was and which direction to go to. Then, I saw a Zomato delivery person on a motorcycle and asked him where the restaurant was. It was already 10 PM and the restaurant closes at 10:30. So, I asked him whether he can drop me off. He agreed and dropped me off at that restaurant. It was 4-5 km from that metro station. I tipped him and expressed my gratefulness for the help. He refused to take the tip, but I insisted and he accepted. I entered the restaurant and it was coming to a close, so many items were not available. I ordered some Kadhai Paneer (only item left) with naan. It tasted fine. Since the next day was Thiruvonam, I asked the restaurant about the Sadya thali menu and prices for the next day. I planned to eat Sadya thali at that restaurant, but my plans got changed later.
Onam sadya menu from Brindhavan restaurant.

Day 2: Onam celebrations Next day, on 29th of August 2023, we had plan to leave for Wayanad. Wayanad is a hill station in Kerala and a famous tourist spot. Praveen suggested to visit Munnar as it is far closer to Kochi than Wayanad (80 km vs 250 km). But I had already visited Munnar in my previous trips, so we chose Wayanad. We had a train late night from Ernakulam Junction (at 23:30 hours) to Kozhikode, which is the nearest railway station from Wayanad. So, we checked out in the morning as we had plans to roam around in Kochi before taking the train. Zostel was celebrating Onam on that day. To opt-in, we had to pay 400 rupees, which included a Sadya Thali and a mundu. Me and Suresh paid the amount and opted in for the celebrations. Sadya thali had Rice, Sambhar, Rasam, Avial, Banana Chips, Pineapple Pachadi, Pappadam, many types of pickels and chutneys, Pal Ada Payasam and Coconut jaggery Pasam. And, there was water too :). Those payasams were really great and I had one more round of them. Later, I had a lot of variety of payasams during the DebConf.
Sadya lined up for serving
Sadya thali served on banana leaf.
So, we hung out in the common room and put our luggage there. We played UNO and had conversations with other travellers in the hostel. I had a fun time there and I still think it is one of the best hostel experiences I had. We made good friends with Saiduth (Telangana) and Shwetank (Uttarakhand). They were already aware about the software like debian, and we had some detailed conversations about the Free Software movement. I remember explaining the difference between the terms Open Source and Free Software . I also told them about the Streetcomplete app, a beginner friendly app to edit OpenStreetMap. We had dinner at a place nearby (named Palaraam), but again, the vegetarian options were very limited! After dinner, we came back to the Zostel and me and Suresh left for Ernakulam Junction to catch our train Maveli Express (16604).

Day 3: Going to Wayanad Maveli Express was scheduled to reach Kozhikode at 03:25 (morning). I had set alarms from 03:00 to 03:30, with the gap of 10 minutes. Every time I woke up, I turned off the alarm. Then I woke up and saw train reaching the Kozhikode station and woke up Suresh for deboarding. But then I noticed that the train is actually leaving the station, not arriving! This means we missed our stop. Now we looked at the next stops and whether we can deboard there. I was very sleepy and wanted to take a retiring room at some station before continuing our journey to Wayanad. The next stop was Quilandi and we checked online that it didn t have a retiring room. So, we skipped this stop. We got off at the next stop named Vadakara and found out no retiring room was available. So, we asked about information regarding bus for Wayanad and they said that there is a bus to Wayanad around 07:00 hours from bus station which was a few kilometres from the railway station. We took a bus for Kalpetta (in Wayanad) at around 07:00. The destination of the buses were written in Malayalam, which we could not read. Once again, the locals helped us to get on to the bus to Kalpetta. Vadakara is not a big city and it can be hard to find people who know good Hindi or English, unlike Kochi. Despite language issues, I had no problem there in navigation, thanks to locals. I mostly spent time sleeping during the bus journey. A few hours later, the bus dropped us at Kalpetta. We had a booking at a hostel in Rippon village. It was 16 km from Kalpetta. On the way, we were treated with beautiful views of nature, which was present everywhere in Wayanad. The place was covered with tea gardens and our eyes were treated with beautiful scenery at every corner.
We were treated with such views during the Wayanad trip.
Rippon village was a very quiet place and I liked the calm atmosphere. This place is blessed by nature and has stunning scenery. I found English was more common than Hindi in Wayanad. Locals were very nice and helped me, even if they didn t know my language.
A road in Rippon.
After catching some sleep at the hostel, I went out in the afternoon. I hitchhiked to reach the main road from the hostel. I bought more spices from a nearby shop and realized that I should have waited for my visit to Wayanad to buy cardamom, which I already bought from Kochi. Then, I was looking for post office to send spices home. The people at the spices shop told me that the nearby Rippon post office was closed by that time, but the post office at Meppadi was open, which was 5 km from there. I went to Meppadi and saw the post office closes at 15:00, but I reached five minutes late. My packing was not very good and they asked me to pack it tighter. There was a shop near the post office and the people there gave me a cardboard and tapes, and helped pack my stuff for the post. By the time I went to the post office again, it was 15:30. But they accepted my parcel for post.

Day 4: Kanthanpara Falls, Zostel Wayanad and Karapuzha Dam Kanthanpara waterfalls were 2 km from the hostel. I hitchhiked to the place from the hostel on a scooty. Entry ticket was worth Rs 40. There were good views inside and nothing much to see except the waterfalls.
Entry to Kanthanpara Falls.
Kanthanpara Falls.
We had a booking at Zostel Wayanad for this day and so we shifted there. Again, as with their Ernakulam branch, they asked me to fill a form which required signing in using Google, but when I said I don t have a Google account they checked me in without that. There were tea gardens inside the Zostel boundaries and the property was beautiful.
A view of Zostel Wayanad.
A map of Wayanad showing tourist places.
A view from inside the Zostel Wayanad property.
Later in the evening, I went to Karapuzha Dam. I witnessed a beautiful sunset during the journey. Karapuzha dam had many activites, like ziplining, and was nice to roam around. Chembra Peak is near to the Zostel Wayanad. So, I was planning to trek to the heart shaped lake. It was suggested by Praveen and looking online, this trek seemed worth doing. There was an issue however. The charges for trek were Rs 1770 for upto five people. So, if I go alone I will have to spend Rs 1770 for the trek. If I go with another person, we split Rs 1770 into two, and so on. The optimal way to do it is to go in a group of five (you included :D). I asked front desk at Zostel if they can connect me with people going to Chembra peak the next day, and they told me about a group of four people planning to go to Chembra peak the next day. I got lucky! All four of them were from Kerala and worked in Qatar.

Day 5: Chembra peak trek The date was 1st September 2023. I woke up early (05:30 in the morning) for the Chembra peak trek. I had bought hiking shoes especially for trekking, which turned out to be a very good idea. The ticket counter opens at 07:00. The group of four with which I planned to trek met me around 06:00 in the Zostel. We went to the ticket counter around 06:30. We had breakfast at shops selling Maggi noodles and bread omlette near the ticket counter. It was a hot day and the trek was difficult for an inexperienced person like me. The scenery was green and beautiful throughout.
Terrain during trekking towards the Chembra peak.
Heart-shaped lake at the Chembra peak.
Me at the heart-shaped lake.
Views from the top of the Chembra peak.
View of another peak from the heart-shaped lake.
While returning from the trek, I found out a shop selling bamboo rice, which I bought and will make bamboo rice payasam out of it at home (I have some coconut milk from Kerala too ;)). We returned to Zostel in the afternoon. I had muscle pain after the trek and it has still not completely disappeared. At night, we took a bus from Kalpetta to Kozhikode in order to return to Kochi.

Day 6: Return to Kochi At midnight of 2nd of September, we reached Kozhikode bus stand. Then we roamed around for something to eat. I didn t find anything vegetarian to eat. No surprises there! Then we went to Kozhikode railway station and looked for retiring rooms, but no luck there. We waited at the station and took the next train to Kochi at 03:30 and reached Ernakulam Junction at 07:30 (half hours before train s scheduled time!). From there, we went to Zostel Fort Kochi and stayed one night there and checked out next morning.

Day 7: Roaming around in Fort Kochi On 3rd of September, we roamed around in Fort Kochi. We visited the usual places - St Francis Church, Dutch Palace, Jew Town, Pardesi Synagogue. I also visited some homestays and the owners were very happy to show their place even when I made it clear that I was not looking for a stay. In the evening, we went to Kakkanad to attend DebConf. The story continues in my DebConf23 blog post.

12 October 2023

Freexian Collaborators: Monthly report about Debian Long Term Support, September 2023 (by Santiago Ruano Rinc n)

Like each month, have a look at the work funded by Freexian s Debian LTS offering.

Debian LTS contributors In September, 21 contributors have been paid to work on Debian LTS, their reports are available:
  • Abhijith PA did 10.0h (out of 0h assigned and 14.0h from previous period), thus carrying over 4.0h to the next month.
  • Adrian Bunk did 7.0h (out of 17.0h assigned), thus carrying over 10.0h to the next month.
  • Anton Gladky did 9.5h (out of 7.5h assigned and 7.5h from previous period), thus carrying over 5.5h to the next month.
  • Bastien Roucari s did 16.0h (out of 15.5h assigned and 1.5h from previous period), thus carrying over 1.0h to the next month.
  • Ben Hutchings did 17.0h (out of 17.0h assigned).
  • Chris Lamb did 17.0h (out of 17.0h assigned).
  • Emilio Pozuelo Monfort did 30.0h (out of 30.0h assigned).
  • Guilhem Moulin did 18.25h (out of 18.25h assigned).
  • Helmut Grohne did 10.0h (out of 10.0h assigned).
  • Lee Garrett did 17.0h (out of 16.5h assigned and 0.5h from previous period).
  • Markus Koschany did 40.0h (out of 40.0h assigned).
  • Ola Lundqvist did 4.5h (out of 0h assigned and 24.0h from previous period), thus carrying over 19.5h to the next month.
  • Roberto C. S nchez did 5.0h (out of 12.0h assigned), thus carrying over 7.0h to the next month.
  • Santiago Ruano Rinc n did 7.75h (out of 16.0h assigned), thus carrying over 8.25h to the next month.
  • Sean Whitton did 7.0h (out of 7.0h assigned).
  • Sylvain Beucler did 10.5h (out of 17.0h assigned), thus carrying over 6.5h to the next month.
  • Thorsten Alteholz did 14.0h (out of 14.0h assigned).
  • Tobias Frost did 13.25h (out of 16.0h assigned), thus carrying over 2.75h to the next month.

Evolution of the situation In September, we have released 44 DLAs. The month of September was a busy month for the LTS Team. A notable security issue fixed in September was the high-severity CVE-2023-4863, a heap buffer overflow that allowed remote attackers to perform an out-of-bounds memory write via a crafted WebP file. This CVE was covered by the three DLAs of different packages: firefox-esr, libwebp and thunderbird. The libwebp backported patch was sent to upstream, who adapted and applied it to the 0.6.1 branch. It is also worth noting that LTS contributor Markus Koschany included in his work updates to packages in Debian Bullseye and Bookworm, that are under the umbrella of the Security Team: xrdp, jetty9 and mosquitto. As every month, there was important behind-the-scenes work by the Front Desk staff, who triaged, analyzed and reviewed dozens of vulnerabilities, to decide if they warrant a security update. This is very important work, since we need to trade-off between the frequency of updates and the stability of the LTS release.

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10 October 2023

Matthias Klumpp: How to indicate device compatibility for your app in MetaInfo data

At the moment I am hard at work putting together the final bits for the AppStream 1.0 release (hopefully to be released this month). The new release comes with many new new features, an improved developer API and removal of most deprecated things (so it carefully breaks compatibility with very old data and the previous C API). One of the tasks for the upcoming 1.0 release was #481 asking about a formal way to distinguish Linux phone applications from desktop applications. AppStream infamously does not support any is-for-phone label for software components, instead the decision whether something is compatible with a device is based the the device s capabilities and the component s requirements. This allows for truly adaptive applications to describe their requirements correctly, and does not lock us into form factors going into the future, as there are many and the feature range between a phone, a tablet and a tiny laptop is quite fluid. Of course the match to current device capabilities check does not work if you are a website ranking phone compatibility. It also does not really work if you are a developer and want to know which devices your component / application will actually be considered compatible with. One goal for AppStream 1.0 is to have its library provide more complete building blocks to software centers. Instead of just a here s the data, interpret it according to the specification API, libappstream now interprets the specification for the application and provides API to handle most common operations like checking device compatibility. For developers, AppStream also now implements a few virtual chassis configurations , to roughly gauge which configurations a component may be compatible with. To test the new code, I ran it against the large Debian and Flatpak repositories to check which applications are considered compatible with what chassis/device type already. The result was fairly disastrous, with many applications not specifying compatibility correctly (many do, but it s by far not the norm!). Which brings me to the actual topic of this blog post: Very few seem to really know how to mark an application compatible with certain screen sizes and inputs! This is most certainly a matter of incomplete guides and good templates, so maybe this post can help with that a bit:

The ultimate cheat-sheet to mark your app chassis-type compatible As a quick reminder, compatibility is indicated using AppStream s relations system: A requires relation indicates that the system will not run at all or will run terribly if the requirement is not met. If the requirement is not met, it should not be installable on a system. A recommends relation means that it would be advantageous to have the recommended items, but it s not essential to run the application (it may run with a degraded experience without the recommended things though). And a supports relation means a given interface/device/control/etc. is supported by this application, but the application may work completely fine without it.

I have a desktop-only application A desktop-only application is characterized by needing a larger screen to fit the application, and requiring a physical keyboard and accurate mouse input. This type is assumed by default if no capabilities are set for an application, but it s better to be explicit. This is the metadata you need:
<component type="desktop-application">
  <id>org.example.desktopapp</id>
  <name>DesktopApp</name>
  [...]
  <requires>
    <display_length>768</display_length>
    <control>keyboard</control>
    <control>pointing</control>
  </requires>
  [...]
</component>
With this requires relation, you require a small-desktop sized screen (at least 768 device-independent pixels (dp) on its smallest edge) and require a keyboard and mouse to be present / connectable. Of course, if your application needs more minimum space, adjust the requirement accordingly. Note that if the requirement is not met, your application may not be offered for installation.
Note: Device-independent / logical pixels One logical pixel (= device independent pixel) roughly corresponds to the visual angle of one pixel on a device with a pixel density of 96 dpi (for historical X11 reasons) and a distance from the observer of about 52 cm, making the physical pixel about 0.26 mm in size. When using logical pixels as unit, they might not always map to exact physical lengths as their exact size is defined by the device providing the display. They do however accurately depict the maximum amount of pixels that can be drawn in the depicted direction on the device s display space. AppStream always uses logical pixels when measuring lengths in pixels.

I have an application that works on mobile and on desktop / an adaptive app Adaptive applications have fewer hard requirements, but a wide range of support for controls and screen sizes. For example, they support touch input, unlike desktop apps. An example MetaInfo snippet for these kind of apps may look like this:
<component type="desktop-application">
  <id>org.example.adaptive_app</id>
  <name>AdaptiveApp</name>
  [...]
  <requires>
    <display_length>360</display_length>
  </requires>
  <supports>
    <control>keyboard</control>
    <control>pointing</control>
    <control>touch</control>
  </supports>
  [...]
</component>
Unlike the pure desktop application, this adaptive application requires a much smaller lowest display edge length, and also supports touch input, in addition to keyboard and mouse/touchpad precision input.

I have a pure phone/table app Making an application a pure phone application is tricky: We need to mark it as compatible with phones only, while not completely preventing its installation on non-phone devices (even though its UI is horrible, you may want to test the app, and software centers may allow its installation when requested explicitly even if they don t show it by default). This is how to achieve that result:
<component type="desktop-application">
  <id>org.example.phoneapp</id>
  <name>PhoneApp</name>
  [...]
  <requires>
    <display_length>360</display_length>
  </requires>
  <recommends>
    <display_length compare="lt">1280</display_length>
    <control>touch</control>
  </recommends>
  [...]
</component>
We require a phone-sized display minimum edge size (adjust to a value that is fit for your app!), but then also recommend the screen to have a smaller edge size than a larger tablet/laptop, while also recommending touch input and not listing any support for keyboard and mouse. Please note that this blog post is of course not a comprehensive guide, so if you want to dive deeper into what you can do with requires/recommends/suggests/supports, you may want to have a look at the relations tags described in the AppStream specification.

Validation It is still easy to make mistakes with the system requirements metadata, which is why AppStream 1.0 will provide more commands to check MetaInfo files for system compatibility. Current pre-1.0 AppStream versions already have an is-satisfied command to check if the application is compatible with the currently running operating system:
:~$ appstreamcli is-satisfied ./org.example.adaptive_app.metainfo.xml
Relation check for: */*/*/org.example.adaptive_app/*
Requirements:
   Unable to check display size: Can not read information without GUI toolkit access.
Recommendations:
   No recommended items are set for this software.
Supported:
   Physical keyboard found.
   Pointing device (e.g. a mouse or touchpad) found.
   This software supports touch input.
In addition to this command, AppStream 1.0 will introduce a new one as well: check-syscompat. This command will check the component against libappstream s mock system configurations that define a most common (whatever that is at the time) configuration for a respective chassis type. If you pass the --details flag, you can even get an explanation why the component was considered or not considered for a specific chassis type:
:~$ appstreamcli check-syscompat --details ./org.example.phoneapp.metainfo.xml
Chassis compatibility check for: */*/*/org.example.phoneapp/*
Desktop:
   Incompatible
   recommends: This software recommends a display with its shortest edge
   being << 1280 px in size, but the display of this device has 1280 px.
   recommends: This software recommends a touch input device.
Laptop:
   Incompatible
   recommends: This software recommends a display with its shortest edge 
   being << 1280 px in size, but the display of this device has 1280 px.
   recommends: This software recommends a touch input device.
Server:
   Incompatible
   requires: This software needs a display for graphical content.
   recommends: This software needs a display for graphical content.
   recommends: This software recommends a touch input device.
Tablet:
   Compatible (100%)
Handset:
   Compatible (100%)
I hope this is helpful for people. Happy metadata writing!

Russ Allbery: Review: Chilling Effect

Review: Chilling Effect, by Valerie Valdes
Series: Chilling Effect #1
Publisher: Harper Voyager
Copyright: September 2019
Printing: 2020
ISBN: 0-06-287724-0
Format: Kindle
Pages: 420
Chilling Effect is a space opera, kind of; more on the genre classification in a moment. It is the first volume of a series, although it reaches a reasonable conclusion on its own. It was Valerie Valdes's first novel. Captain Eva Innocente's line of work used to be less than lawful, following in the footsteps of her father. She got out of that life and got her own crew and ship. Now, the La Sirena Negra and its crew do small transport jobs for just enough money to stay afloat. Or, maybe, a bit less than that, when the recipient of a crate full of psychic escape-artist cats goes bankrupt before she can deliver it and get paid. It's a marginal and tenuous life, but at least she isn't doing anything shady. Then the Fridge kidnaps her sister. The Fridge is a shadowy organization of extortionists whose modus operandi is to kidnap a family member of their target, stuff them in cryogenic suspension, and demand obedience lest the family member be sold off as indentured labor after a few decades as a popsicle. Eva will be given missions that she and her crew have to perform. If she performs them well, she will pay off the price of her sister's release. Eventually. Oh, and she's not allowed to tell anyone. I found it hard to place the subgenre of this novel more specifically than comedy-adventure. The technology fits space opera: there are psychic cats, pilots who treat ships as extensions of their own body, brain parasites, a random intergalactic warlord, and very few attempts to explain anything with scientific principles. However, the stakes aren't on the scale that space opera usually goes for. Eva and her crew aren't going to topple governments or form rebellions. They're just trying to survive in a galaxy full of abusive corporations, dodgy clients, and the occasional alien who requires you to carry extensive documentation to prove that you can't be hunted for meat. It is also, as you might guess from that description, occasionally funny. That part of the book didn't mesh for me. Eva is truly afraid for her sister, and some of the events in the book are quite sinister, but the antagonist is an organization called The Fridge that puts people in fridges. Sexual harassment in a bar turns into obsessive stalking by a crazed intergalactic warlord who frequently interrupts the plot by randomly blasting things with his fleet, which felt like something from Hitchhiker's Guide to the Galaxy. The stakes for Eva, and her frustrations at being dragged back into a life she escaped, felt too high for the wacky, comic descriptions of the problems she gets into. My biggest complaint, though, is that the plot is driven by people not telling other people critical information they should know. Eva is keeping major secrets from her crew for nearly the entire book. Other people are also keeping information from Eva. There is a romance subplot driven almost entirely by both parties refusing to talk to each other about the existence of a romance subplot. For some people, this is catnip, but it's one of my least favorite fictional tropes and I found much of the book both frustrating and stressful. Fictional characters keeping important secrets from each other apparently raises my blood pressure. One of the things I did like about this book is that Eva is Hispanic and speaks like it. She resorts to Spanish frequently for curses, untranslatable phrases, aphorisms, derogatory comments, and similar types of emotional communication that don't feel right in a second language. Most of the time one can figure out the meaning from context, but Valdes doesn't feel obligated to hold the reader's hand and explain everything. I liked that. I think this approach is more viable in these days of ebook readers that can attempt translations on demand, and I think it does a lot to make Eva feel like a real person. I think the characters are the best part of this book, once one gets past the frustration of their refusal to talk to each other. Eva and the alien ship engineer get the most screen time, but Pink, Eva's honest-to-a-fault friend, was probably my favorite character. I also really enjoyed Min, the ship pilot whose primary goal is to be able to jack into the ship and treat it as her body, and otherwise doesn't particularly care about the rest of the plot as long as she gets paid. A lot of books about ship crews like this one lean hard into found family. This one felt more like a group of coworkers, with varying degrees of friendship and level of interest in their shared endeavors, but without the too-common shorthand of making the less-engaged crew members either some type of villain or someone who needs to be drawn out and turned into a best friend or love interest. It's okay for a job to just be a job, even if it's one where you're around the same people all the time. People who work on actual ships do it all the time. This is a half-serious, half-comic action romp that turned out to not be my thing, but I can see why others will enjoy it. Be prepared for a whole lot of communication failures and an uneven emotional tone, but if you're looking for a space-ships-and-aliens story that doesn't take itself very seriously and has some vague YA vibes, this may work for you. Followed by Prime Deceptions, although I didn't like this well enough to read on. Rating: 6 out of 10

8 October 2023

Sahil Dhiman: Lap 24

Twenty-four is a big number. More than one/fourth (or more) of my life is behind me now. At this point, I truly feel like I have become an adult; mentally and physically. Another year seem to have gone by quickly. I still vividly remember writing 23 and Counting and here I m writing the next one so soon. Probably the lowest I felt ever on my birthday; with loss of Abraham and on the other hand, medical issues with a dear one. Didn t even felt like birthday was almost here. The loss of Abraham, taught me to care for people more and meet cherish everyone. I m grateful for all the people who supported and cared for me and others during times of grief when things went numb. Thank you! Also, for the first time ever, I went to office on my birthday. This probably would become a norm in coming years. Didn t felt like doing anything, so just went to office. The cake, wishes and calls kept coming in throughout the day. I m grateful for the all people around for remembering :) This year marked my first official job switch where I moved from MakeMyTrip to Unmukti as a GNU/Linux Network Systems engineer (that s a mouthful of a job role, I know) where I do anything and everything ranging from system admin, network engineering, a bit of social media, chronicling stuff on company blog and bringing up new applications as per requirement. Moving from MMT to Unmukti was a big cultural shift. From a full-blown corporate with more than 3 thousand employees to a small 5-person team. People still think I work for a startup on hearing the low head count, though Unmukti is a 13 year old organization. I get the freedom to work at my own pace and put my ideas in larger technical discussions, while also actively participating in the community, which I m truly grateful of. I go full geek here and almost everyone here is on the same spectrum, so things technical or societal discussions just naturally flow. The months of August-September again marked the Great Refresh. For reasons unforeseen, I have had to pack my stuff again and move, albeit to just next door for now, but that gave me the much need opportunity to sift through my belongings here. As usual, I threw a boatload of stuff which was of no use and/or just hogging space. My wardrobe cupboard finally got cleaned and sorted, with old and new clothes getting (re)discovered. The Refresh is always a pain with loads of collating stuff in carry worthy bags and hauling stuff but as usual, there s nothing else I can do other than just pack and move. This year also culminated our four plus years of work for organizing annual Debian conference, DebConf to India. DebConf23 happened in Kochi, Kerala from 3rd September to 17th September (including DebCamp). First concrete work to bring conference to India was done Raju Dev who made the first bid during DebConf18 in Hsinchu, Taiwan. We lost but won during the next year bid at DebConf19 Curitiba, Brazil in 2019. I joined the efforts after meeting the team online after DebConf20. Initially started with the publicity team, but we didn t need much publicity for event, I was later asked to join sponsors/fundraising team. That turned out to be quite an experience. Then the conference itself turned to be a good experience. More on that in an upcoming DebConf23 blog post, which will come eventually. After seeing how things work out in Debian in 2020, I had the goal to become a Debian Developer (DD) before DebConf23, which gave me almost three years to get involved and get recognized to become a DD. I was more excited to grab sahil AT debian.org, a short email with only my name and no number of characters after it. After, quite a while, I dropped the hope of become a DD because I wasn t successful in my attempts to meaningfully package and technically contribute to the project. But people in Debian India later convinced me that I have done enough to become a Debian Developer, non uploading, purely by showing up and helping around all for the Debian conferences. I applied and got sponsored (i.e. supported) for my request by srud and Praveen. Finally, on 23rd Feb, I officially became part of Debian project as 14th (at the moment) Debian Developer from India. Got sahil AT debian.org too :) For some grace, I also became a DD before DebConf23. Becoming a DD didn t change anything much though, I still believe, it might have helped secure me a job though. Also, worth mentioning is my increased interest in OpenStreetMap (OSM) mapping. I heavily mapped this year and went around for mapathon-meetups too. One step towards a better OSM and more community engagement around it. Looking back at my blog, this year around, it seems mostly dotted with Debian and one OSM post. Significant shift from the range of topics I use to write about in the past year but blogging this year wasn t a go-to activity. Other stuff kept me busy. Living in Gurugram has shown me many facades of life from which I was shielded or didn t come across earlier. It made me realize all the privileges which has helped me along the way, which became apparent while living almost alone here and managing thing by oneself.

6 October 2023

Russ Allbery: Review: The Far Reaches

Review: The Far Reaches, edited by John Joseph Adams
Publisher: Amazon Original Stories
Copyright: June 2023
ISBN: 1-6625-1572-3
ISBN: 1-6625-1622-3
ISBN: 1-6625-1503-0
ISBN: 1-6625-1567-7
ISBN: 1-6625-1678-9
ISBN: 1-6625-1533-2
Format: Kindle
Pages: 219
Amazon has been releasing anthologies of original short SFF with various guest editors, free for Amazon Prime members. I previously tried Black Stars (edited by Nisi Shawl and Latoya Peterson) and Forward (edited by Blake Crouch). Neither were that good, but the second was much worse than the first. Amazon recently released a new collection, this time edited by long-standing SFF anthology editor John Joseph Adams and featuring a new story by Ann Leckie, which sounded promising enough to give them another chance. The definition of insanity is doing the same thing over and over again and expecting different results. As with the previous anthologies, each story is available separately for purchase or Amazon Prime "borrowing" with separate ISBNs. The sidebar cover is for the first in the sequence. Unlike the previous collections, which were longer novelettes or novellas, my guess is all of these are in the novelette range. (I did not do a word count.) If you're considering this anthology, read the Okorafor story ("Just Out of Jupiter's Reach"), consider "How It Unfolds" by James S.A. Corey, and avoid the rest. "How It Unfolds" by James S.A. Corey: Humans have invented a new form of physics called "slow light," which can duplicate any object that is scanned. The energy expense is extremely high, so the result is not a post-scarcity paradise. What the technology does offer, however, is a possible route to interstellar colonization: duplicate a team of volunteers and a ship full of bootstrapping equipment, and send copies to a bunch of promising-looking exoplanets. One of them might succeed. The premise is interesting. The twists Corey adds on top are even better. What can be duplicated once can be duplicated again, perhaps with more information. This is a lovely science fiction idea story that unfortunately bogs down because the authors couldn't think of anywhere better to go with it than relationship drama. I found the focus annoying, but the ideas are still very neat. (7) "Void" by Veronica Roth: A maintenance worker on a slower-than-light passenger ship making the run between Sol and Centauri unexpectedly is called to handle a dead body. A passenger has been murdered, two days outside the Sol system. Ace is in no way qualified to investigate the murder, nor is it her job, but she's watched a lot of crime dramas and she has met the victim before. The temptation to start poking around is impossible to resist. It's been a long time since I've read a story built around the differing experiences of time for people who stay on planets and people who spend most of their time traveling at relativistic speeds. It's a bit of a retro idea from an earlier era of science fiction, but it's still a good story hook for a murder mystery. None of the characters are that memorable and Roth never got me fully invested in the story, but this was still a pleasant way to pass the time. (6) "Falling Bodies" by Rebecca Roanhorse: Ira is the adopted son of a Genteel senator. He was a social experiment in civilizing the humans: rescue a human orphan and give him the best of Genteel society to see if he could behave himself appropriately. The answer was no, which is how Ira finds himself on Long Reach Station with a parole officer and a schooling opportunity, hopefully far enough from his previous mistakes for a second chance. Everyone else seems to like Rebecca Roanhorse's writing better than I do, and this is no exception. Beneath the veneer of a coming-of-age story with a twist of political intrigue, this is brutal, depressing, and awful, with an ending that needs a lot of content warnings. I'm sorry that I read it. (3) "The Long Game" by Ann Leckie: The Imperial Radch trilogy are some of my favorite science fiction novels of all time, but I am finding Leckie's other work a bit hit and miss. I have yet to read a novel of hers that I didn't like, but the short fiction I've read leans more heavily into exploring weird and alien perspectives, which is not my favorite part of her work. This story is firmly in that category: the first-person protagonist is a small tentacled alien creature, a bit like a swamp-dwelling octopus. I think I see what Leckie is doing here: balancing cynicism and optimism, exploring how lifespans influence thinking and planning, and making some subtle points about colonialism. But as a reading experience, I didn't enjoy it. I never liked any of the characters, and the conclusion of the story is the unsettling sort of main-character optimism that seems rather less optimistic to the reader. (4) "Just Out of Jupiter's Reach" by Nnedi Okorafor: K rm n scientists have found a way to grow living ships that can achieve a symbiosis with a human pilot, but the requirements for that symbiosis are very strict and hard to predict. The result was a planet-wide search using genetic testing to find the rare and possibly nonexistent matches. They found seven people. The deal was simple: spend ten years in space, alone, in her ship. No contact with any other human except at the midpoint, when the seven ships were allowed to meet up for a week. Two million euros a year, for as long as she followed the rules, and the opportunity to be part of a great experiment, providing data that will hopefully lead to humans becoming a spacefaring species. The core of this story is told during the seven days in the middle of the mission, and thus centers on people unfamiliar with human contact trying to navigate social relationships after five years in symbiotic ships that reshape themselves to their whims and personalities. The ships themselves link so that the others can tour, which offers both a good opportunity for interesting description and a concretized metaphor about meeting other people. I adore symbiotic spaceships, so this story had me at the premise. The surface plot is very psychological, and I didn't entirely click with it, but the sense of wonder vibes beneath that surface were wonderful. It also feels fresh and new: I've seen most of the ideas before, but not presented or written this way, or approached from quite this angle. Definitely the best story of the anthology. (8) "Slow Time Between the Stars" by John Scalzi: This, on the other hand, was a complete waste of time, redeemed only by being the shortest "story" in the collection. "Story" is generous, since there's only one character and a very dry, linear plot that exists only to make a philosophical point. "Speculative essay" may be closer. The protagonist is the artificial intelligence responsible for Earth's greatest interstellar probe. It is packed with a repository of all of human knowledge and the raw material to create life. Its mission is to find an exoplanet capable of sustaining that life, and then recreate it and support it. The plot, such as it is, follows the AI's decision to abandon that mission and cut off contact with Earth, for reasons that it eventually explains. Every possible beat of this story hit me wrong. The sense of wonder attaches to the most prosaic things and skips over the moments that could have provoked real wonder. The AI is both unbelievable and irritating, with all of the smug self-confidence of an Internet reply guy. The prose is overwrought in all the wrong places ("the finger of God, offering the spark to animate the dirt of another world" would totally be this AI's profile quote under their forum avatar). The only thing I liked about the story is the ethical point that it slowly meanders into, which I think I might agree with and at least find plausible. But it's delivered by the sort of character I would actively leave rooms to avoid, in a style that's about as engrossing as a tax form. Avoid. (2) Rating: 5 out of 10

5 October 2023

Scarlett Gately Moore: KDE: Why KDE snaps Love KDE neon and the Big Move.

KDE neonKDE neon
KDE neon: KDE neon is extremely important to the KDE snaps eco-system as I briefly mentioned in my last post. Why? KDE neon is based on Jammy LTS which is the same as Core 22 base for snaps. Neon has a very useful continuous integration system in place that tests all the things, including dependencies, qml, cmake errors, debian packaging lintian tool and the list go on. This is very important to get packages out that don t break things on user desktops. Once the packages are a lovely shade of green on the neon CI ( or at least all the important issues are resolved ) it is in good shape for snapping. I have scripts that pull the build and runtime dependency information for our application package to use in the snapcraft.yaml. We know this list is complete, because it passed the tests! As applications gain features, they requires newer dependencies than what is provided in the ubuntu jammy repositories. Neon builds those newer dependencies and provides them to our users in the neon aptly repositories. It is much easier and more reliable than tracking down PPAs and hoping they stay maintained. We use the neon user edition repository in our snapcraft file to ensure we are up to date on KDE applications dependency needs. This week my work in Neon included turning jobs green and fixing kio-gdrive which is still qt5, but it s dependency libkgapi is qt6! We have to provide both versions in cases like this which entails tracking both master and the qt5 release branch. Snaps:
KMymoney 5.1
This week begun the big transition from single repository remote-builds to per repository snapcraft and using snap recipes on launchpad. This is an important move for a couple of reasons. We were having major issues with build failures as I pointed out in this bug report on launchpad: https://bugs.launchpad.net/launchpad/+bug/2031307 . This was due to the way remote-build works. It creates temporary snap recipes that builds once and sends back the snap or failure status. This made it very difficult to debug build failures as once the failure status was sent the job disappeared off of launchpad, taking all build logs with it. Now with the per repository snapcraft files, I have set up proper snap recipes on launchpad and the builds are automated by polling the github mirror for changes and it publishes the shiny new snap to candidate for testing or sends me the failure log that I can view at my convenience. This of course is a work in progress as we have 186 snaps currently and there are a few steps to get each one done. But once it is done, it will reduce my workload immensely and make debugging build issues faster. While making the move, I am also updating the snapcraft files for changes within snapcraft, adding cleanup to decrease bloat and fixing bugs! Snap move complete:
Artikulate with Courses
Current WIP: Audiotube, Digikam, Cantor, Neochat I also made a new content pack with KDE frameworks 5.110, but a new Qt 5.15.11 was just released so I will be making a new one tomorrow. The kf6 content snap has come to a halt as the qt6 content snap has stalled. I asked to be given access to the snapcraft file so that I may collaborate, but have not heard back. My mysterious project has reached its end for me. I might get a part time gig doing snaps out of it, but I do not meet the requirements to do any of the engineering of it. It is what it is. Thank you to all who vouched for me, alas it wasn t meant to be. If you can spare some change, I would appreciate it, especially to pay my phone/Internet bill so I can do more Neon and snaps  Thank you for stopping by. Donate https://gofund.me/b8b69e54

30 September 2023

Ian Jackson: DKIM: rotate and publish your keys

If you are an email system administrator, you are probably using DKIM to sign your outgoing emails. You should be rotating the key regularly and automatically, and publishing old private keys. I have just released dkim-rotate 1.0; dkim-rotate is a tool to do this key rotation and publication. If you are an email user, your email provider ought to be doing this. If this is not done, your emails are non-repudiable , meaning that if they are leaked, anyone (eg, journalists, haters) can verify that they are authentic, and prove that to others. This is not desirable (for you). Non-repudiation of emails is undesirable This problem was described at some length in Matthew Green s article Ok Google: please publish your DKIM secret keys. Avoiding non-repudiation sounds a bit like lying. After all, I m advising creating a situation where some people can t verify that something is true, even though it is. So I m advocating casting doubt. Crucially, though, it s doubt about facts that ought to be private. When you send an email, that s between you and the recipient. Normally you don t intend for anyone, anywhere, who happens to get a copy, to be able to verify that it was really you that sent it. In practical terms, this verifiability has already been used by journalists to verify stolen emails. Associated Press provide a verification tool. Advice for all email users As a user, you probably don t want your emails to be non-repudiable. (Other people might want to be able to prove you sent some email, but your email system ought to serve your interests, not theirs.) So, your email provider ought to be rotating their DKIM keys, and publishing their old ones. At a rough guess, your provider probably isn t :-(. How to tell by looking at email headers A quick and dirty way to guess is to have a friend look at the email headers of a message you sent. (It is important that the friend uses a different email provider, since often DKIM signatures are not applied within a single email system.) If your friend sees a DKIM-Signature header then the message is DKIM signed. If they don t, then it wasn t. Most email traversing the public internet is DKIM signed nowadays; so if they don t see the header probably they re not looking using the right tools, or they re actually on the same email system as you. In messages signed by a system running dkim-rotate, there will also be a header about the key rotation, to notify potential verifiers of the situation. Other systems that avoid non-repudiation-through-DKIM might do something similar. dkim-rotate s header looks like this:
DKIM-Signature-Warning: NOTE REGARDING DKIM KEY COMPROMISE
 https://www.chiark.greenend.org.uk/dkim-rotate/README.txt
 https://www.chiark.greenend.org.uk/dkim-rotate/ae/aeb689c2066c5b3fee673355309fe1c7.pem
But an email system might do half of the job of dkim-rotate: regularly rotating the key would cause the signatures of old emails to fail to verify, which is a good start. In that case there probably won t be such a header. Testing verification of new and old messages You can also try verifying the signatures. This isn t entirely straightforward, especially if you don t have access to low-level mail tooling. Your friend will need to be able to save emails as raw whole headers and body, un-decoded, un-rendered. If your friend is using a traditional Unix mail program, they should save the message as an mbox file. Otherwise, ProPublica have instructions for attaching and transferring and obtaining the raw email. (Scroll down to How to Check DKIM and ARC .) Checking that recent emails are verifiable Firstly, have your friend test that they can in fact verify a DKIM signature. This will demonstrate that the next test, where the verification is supposed to fail, is working properly and fails for the right reasons. Send your friend a test email now, and have them do this on a Linux system:
    # save the message as test-email.mbox
    apt install libmail-dkim-perl # or equivalent on another distro
    dkimproxy-verify <test-email.mbox
You should see output containing something like this:
    originator address: ijackson@chiark.greenend.org.uk
    signature identity: @chiark.greenend.org.uk
    verify result: pass
    ...
If the output ontains verify result: fail (body has been altered) then probably your friend didn t manage to faithfully save the unalterered raw message. Checking old emails cannot be verified When you both have that working, have your friend find an older email of yours, from (say) month ago. Perform the same steps. Hopefully they will see something like this:
    originator address: ijackson@chiark.greenend.org.uk
    signature identity: @chiark.greenend.org.uk
    verify result: fail (bad RSA signature)
or maybe
    verify result: invalid (public key: not available)
This indicates that this old email can no longer be verified. That s good: it means that anyone who steals a copy, can t verify it either. If it s leaked, the journalist who receives it won t know it s genuine and unmodified; they should then be suspicious. If your friend sees verify result: pass, then they have verified that that old email of yours is genuine. Anyone who had a copy of the mail can do that. This is good for email thieves, but not for you. For email admins: announcing dkim-rotate 1.0 I have been running dkim-rotate 0.4 on my infrastructure, since last August. and I had entirely forgotten about it: it has run flawlessly for a year. I was reminded of the topic by seeing DKIM in other blog posts. Obviously, it is time to decreee that dkim-rotate is 1.0. If you re a mail system administrator, your users are best served if you use something like dkim-rotate. The package is available in Debian stable, and supports Exim out of the box, but other MTAs should be easy to support too, via some simple ad-hoc scripting. Limitation of this approach Even with this key rotation approach, emails remain nonrepudiable for a short period after they re sent - typically, a few days. Someone who obtains a leaked email very promptly, and shows it to the journalist (for example) right away, can still convince the journalist. This is not great, but at least it doesn t apply to the vast bulk of your email archive. There are possible email protocol improvements which might help, but they re quite out of scope for this article.
Edited 2023-10-01 00:20 +01:00 to fix some grammar


comment count unavailable comments

29 September 2023

Scarlett Gately Moore: KDE: Another Busy Week! KDE neon, Debian, Snaps Oh My!

KDE Plasma 6KDE Plasma 6
I would like to welcome you to my revamped site. It is still a work in progress, so please be patient while I work out the kinks! I have also explained a bit more about myself in my About Me page for those that may have questions about my homesteader lifestyle. Check it out when you have time. My site is mostly my adventures in packaging software in Linux in a variety of formats ( mostly Debian and Ubuntu Snaps containerized packages ). This keeps me very busy, as folks don t realize the importance of packaging. Without it, applications remain in source code form which isn t very usable by the users! While turning the source code into something user friendly we often run into issues and work with upstream ( I am a very strong believer in upstream first ) to resolve any issues. This makes for a better user experience and less buggy software. Workarounds are very hard to maintain and thus fixing it right the first time is the best path! With this said, while I am not strong in any one programming language ( Well maybe Ruby from my CI tooling background ) I am versed in many languages, as I have to understand the code that I am filing bug reports for! We have to have a strong knowledge of being able to understand build failures, debug runtime failures and most importantly we have to be able to fix them, or find the resources to assist in fixing them. As most of you know I am KDE s biggest fan ( There is nothing wrong with Gnome, its a great platform ). So a big portion of my work is dedicated to KDE. A fantastic tool for working on my KDE packaging has been KDE Neon! With the developer version I have all the tools necessary to debug and fix issues that arise. There is also the added bonus of living on the edge and finding out runtime issues right away! That is enough about me for now and on to my weekly round up! KDE neon: Carlos ( check out his new blog! https://www.ethicalconstruct.au/dotclear_blog/ ) and I have been very busy with another round of KDE applications making the move to Qt6. We have finished KDE PIM and KDE Games in Neon/unstable! I have worked out issues with print-manager and re-enabled it in experimental as it s qt6 development is still happening in kf6 branch. Instructions here: https://blog.neon.kde.org/2023/08/04/announcing-kde-neon-experimental/ Fixed issues with a broken kscreenlocker and missing window decorations. You can now safely leave your computer and not worry about that dreaded black screen. Debian: I have uploaded the newest squashfuse to unstable. I have uploaded another NEW dependency for bubblegum golang-github-alecthomas-mango-kong-dev Ubuntu Snaps: This week continues working closely with Jarred Wilson of Canonical in getting his Qt6 content snap in shape for use with my KDE Frameworks 6 snap ( an essential snap to move forward with our next generation Qt6 applications and of course the Plasma snap. I spent some time debugging the neochat snap and fixed some QML issues, but I am now facing issues with wayland. It now works fine for those of us still on X11. I will continue working out wayland. Thank you! I rely on donations to upkeep my everyday living and so far thanks to each and every one of you I have survived almost a full year! It has been scary from time to time, but I am surviving. Until my snap project goes through I must rely on the kindness of my supporters. The proceeds of my donations goes to the following: I have joined the kool kids and moved to Donorbox for donations. Donate I still have Gofundme for those that don t want to signup for yetanotherdonationplatform. https://gofund.me/b8b69e54

22 September 2023

Ravi Dwivedi: Debconf23

Official logo of DebConf23

Introduction DebConf23, the 24th annual Debian Conference, was held in India in the city of Kochi, Kerala from the 3rd to the 17th of September, 2023. Ever since I got to know about it (which was more than an year ago), I was excited to attend DebConf in my home country. This was my second DebConf, as I attended one last year in Kosovo. I was very happy that I didn t need to apply for a visa to attend. I got full bursary to attend the event (thanks a lot to Debian for that!) which is always helpful in covering the expenses, especially if the venue is a five star hotel :) For the conference, I submitted two talks. One was suggested by Sahil on Debian packaging for beginners, while the other was suggested by Praveen who opined that a talk covering broader topics about freedom in self-hosting services will be better, when I started discussing about submitting a talk about prav app project. So I submitted one on Debian packaging for beginners and the other on ideas on sustainable solutions for self-hosting. My friend Suresh - who is enthusiastic about Debian and free software - wanted to attend the DebConf as well. When the registration started, I reminded him about applying. We landed in Kochi on the 28th of August 2023 during the festival of Onam. We celebrated Onam in Kochi, had a trip to Wayanad, and returned to Kochi. On the evening of the 3rd of September, we reached the venue - Four Points Hotel by Sheraton, at Infopark Kochi, Ernakulam, Kerala, India.
Suresh and me celebrating Onam in Kochi.

Hotel overview The hotel had 14 floors, and featured a swimming pool and gym (these were included in our package). The hotel gave us elevator access for only our floor, along with public spaces like the reception, gym, swimming pool, and dining areas. The temperature inside the hotel was pretty cold and I had to buy a jacket to survive. Perhaps the hotel was in cahoots with winterwear companies? :)
Four Points Hotel by Sheraton was the venue of DebConf23. Photo credits: Bilal
Photo of the pool. Photo credits: Andreas Tille.
View from the hotel window.

Meals On the first day, Suresh and I had dinner at the eatery on the third floor. At the entrance, a member of the hotel staff asked us about how many people we wanted a table for. I told her that it s just the two of us at the moment, but (as we are attending a conference) we might be joined by others. Regardless, they gave us a table for just two. Within a few minutes, we were joined by Alper from Turkey and urbec from Germany. So we shifted to a larger table but then we were joined by even more people, so we were busy adding more chairs to our table. urbec had already been in Kerala for the past 5-6 days and was, on one hand, very happy already with the quality and taste of bananas in Kerala and on the other, rather afraid of the spicy food :) Two days later, the lunch and dinner were shifted to the All Spice Restaurant on the 14th floor, but the breakfast was still served at the eatery. Since the eatery (on the 3rd floor) had greater variety of food than the other venue, this move made breakfast the best meal for me and many others. Many attendees from outside India were not accustomed to the spicy food. It is difficult for locals to help them, because what we consider mild can be spicy for others. It is not easy to satisfy everyone at the dining table, but I think the organizing team did a very good job in the food department. (That said, it didn t matter for me after a point, and you will know why.) The pappadam were really good, and I liked the rice labelled Kerala rice . I actually brought that exact rice and pappadam home during my last trip to Kochi and everyone at my home liked it too (thanks to Abhijit PA). I also wished to eat all types of payasams from Kerala and this really happened (thanks to Sruthi who designed the menu). Every meal had a different variety of payasam and it was awesome, although I didn t like some of them, mostly because they were very sweet. Meals were later shifted to the ground floor (taking away the best breakfast option which was the eatery).
This place served as lunch and dinner place and later as hacklab during debconf. Photo credits: Bilal

The excellent Swag Bag The DebConf registration desk was at the second floor. We were given a very nice swag bag. They were available in multiple colors - grey, green, blue, red - and included an umbrella, a steel mug, a multiboot USB drive by Mostly Harmless, a thermal flask, a mug by Canonical, a paper coaster, and stickers. It rained almost every day in Kochi during our stay, so handing out an umbrella to every attendee was a good idea.
Picture of the awesome swag bag given at DebConf23. Photo credits: Ravi Dwivedi

A gift for Nattie During breakfast one day, Nattie (Belgium) expressed the desire to buy a coffee filter. The next time I went to the market, I bought a coffee filter for her as a gift. She seemed happy with the gift and was flattered to receive a gift from a young man :)

Being a mentor There were many newbies who were eager to learn and contribute to Debian. So, I mentored whoever came to me and was interested in learning. I conducted a packaging workshop in the bootcamp, but could only cover how to set up the Debian Unstable environment, and had to leave out how to package (but I covered that in my talk). Carlos (Brazil) gave a keysigning session in the bootcamp. Praveen was also mentoring in the bootcamp. I helped people understand why we sign GPG keys and how to sign them. I planned to take a workshop on it but cancelled it later.

My talk My Debian packaging talk was on the 10th of September, 2023. I had not prepared slides for my Debian packaging talk in advance - I thought that I could do it during the trip, but I didn t get the time so I prepared them on the day before the talk. Since it was mostly a tutorial, the slides did not need much preparation. My thanks to Suresh, who helped me with the slides and made it possible to complete them in such a short time frame. My talk was well-received by the audience, going by their comments. I am glad that I could give an interesting presentation.
My presentation photo. Photo credits: Valessio

Visiting a saree shop After my talk, Suresh, Alper, and I went with Anisa and Kristi - who are both from Albania, and have a never-ending fascination for Indian culture :) - to buy them sarees. We took autos to Kakkanad market and found a shop with a great variety of sarees. I was slightly familiar with the area around the hotel, as I had been there for a week. Indian women usually don t try on sarees while buying - they just select the design. But Anisa wanted to put one on and take a few photos as well. The shop staff did not have a trial saree for this purpose, so they took a saree from a mannequin. It took about an hour for the lady at the shop to help Anisa put on that saree but you could tell that she was in heaven wearing that saree, and she bought it immediately :) Alper also bought a saree to take back to Turkey for his mother. Me and Suresh wanted to buy a kurta which would go well with the mundu we already had, but we could not find anything to our liking.
Selfie with Anisa and Kristi. Photo credits: Anisa.

Cheese and Wine Party On the 11th of September we had the Cheese and Wine Party, a tradition of every DebConf. I brought Kaju Samosa and Nankhatai from home. Many attendees expressed their appreciation for the samosas. During the party, I was with Abhas and had a lot of fun. Abhas brought packets of paan and served them at the Cheese and Wine Party. We discussed interesting things and ate burgers. But due to the restrictive alcohol laws in the state, it was less fun compared to the previous DebConfs - you could only drink alcohol served by the hotel in public places. If you bought your own alcohol, you could only drink in private places (such as in your room, or a friend s room), but not in public places.
Me helping with the Cheese and Wine Party.

Party at my room Last year, Joenio (Brazilian) brought pastis from France which I liked. He brought the same alocholic drink this year too. So I invited him to my room after the Cheese and Wine party to have pastis. My idea was to have them with my roommate Suresh and Joenio. But then we permitted Joenio to bring as many people as he wanted and he ended up bringing some ten people. Suddenly, the room was crowded. I was having good time at the party, serving them the snacks given to me by Abhas. The news of an alcohol party at my room spread like wildfire. Soon there were so many people that the AC became ineffective and I found myself sweating. I left the room and roamed around in the hotel for some fresh air. I came back after about 1.5 hours - for most part, I was sitting at the ground floor with TK Saurabh. And then I met Abraham near the gym (which was my last meeting with him). I came back to my room at around 2:30 AM. Nobody seemed to have realized that I was gone. They were thanking me for hosting such a good party. A lot of people left at that point and the remaining people were playing songs and dancing (everyone was dancing all along!). I had no energy left to dance and to join them. They left around 03:00 AM. But I am glad that people enjoyed partying in my room.
This picture was taken when there were few people in my room for the party.

Sadhya Thali On the 12th of September, we had a sadhya thali for lunch. It is a vegetarian thali served on a banana leaf on the eve of Thiruvonam. It wasn t Thiruvonam on this day, but we got a special and filling lunch. The rasam and payasam were especially yummy.
Sadhya Thali: A vegetarian meal served on banana leaf. Payasam and rasam were especially yummy! Photo credits: Ravi Dwivedi.
Sadhya thali being served at debconf23. Photo credits: Bilal

Day trip On the 13th of September, we had a daytrip. I chose the daytrip houseboat in Allepey. Suresh chose the same, and we registered for it as soon as it was open. This was the most sought-after daytrip by the DebConf attendees - around 80 people registered for it. Our bus was set to leave at 9 AM on the 13th of September. Me and Suresh woke up at 8:40 and hurried to get to the bus in time. It took two hours to reach the venue where we get the houseboat. The houseboat experience was good. The trip featured some good scenery. I got to experience the renowned Kerala backwaters. We were served food on the boat. We also stopped at a place and had coconut water. By evening, we came back to the place where we had boarded the boat.
Group photo of our daytrip. Photo credits: Radhika Jhalani

A good friend lost When we came back from the daytrip, we received news that Abhraham Raji was involved in a fatal accident during a kayaking trip. Abraham Raji was a very good friend of mine. In my Albania-Kosovo-Dubai trip last year, he was my roommate at our Tirana apartment. I roamed around in Dubai with him, and we had many discussions during DebConf22 Kosovo. He was the one who took the photo of me on my homepage. I also met him in MiniDebConf22 Palakkad and MiniDebConf23 Tamil Nadu, and went to his flat in Kochi this year in June. We had many projects in common. He was a Free Software activist and was the designer of the DebConf23 logo, in addition to those for other Debian events in India.
A selfie in memory of Abraham.
We were all fairly shocked by the news. I was devastated. Food lost its taste, and it became difficult to sleep. That night, Anisa and Kristi cheered me up and gave me company. Thanks a lot to them. The next day, Joenio also tried to console me. I thank him for doing a great job. I thank everyone who helped me in coping with the difficult situation. On the next day (the 14th of September), the Debian project leader Jonathan Carter addressed and announced the news officially. THe Debian project also mentioned it on their website. Abraham was supposed to give a talk, but following the incident, all talks were cancelled for the day. The conference dinner was also cancelled. As I write, 9 days have passed since his death, but even now I cannot come to terms with it.

Visiting Abraham s house On the 15th of September, the conference ran two buses from the hotel to Abraham s house in Kottayam (2 hours ride). I hopped in the first bus and my mood was not very good. Evangelos (Germany) was sitting opposite me, and he began conversing with me. The distraction helped and I was back to normal for a while. Thanks to Evangelos as he supported me a lot on that trip. He was also very impressed by my use of the StreetComplete app which I was using to edit OpenStreetMap. In two hours, we reached Abraham s house. I couldn t control myself and burst into tears. I went to see the body. I met his family (mother, father and sister), but I had nothing to say and I felt helpless. Owing to the loss of sleep and appetite over the past few days, I had no energy, and didn t think it was good idea for me to stay there. I went back by taking the bus after one hour and had lunch at the hotel. I withdrew my talk scheduled for the 16th of September.

A Japanese gift I got a nice Japanese gift from Niibe Yutaka (Japan) - a folder to keep papers which had ancient Japanese manga characters. He said he felt guilty as he swapped his talk with me and so it got rescheduled from 12th September to 16 September which I withdrew later.
Thanks to Niibe Yutaka (the person towards your right hand) from Japan (FSIJ), who gave me a wonderful Japanese gift during debconf23: A folder to keep pages with ancient Japanese manga characters printed on it. I realized I immediately needed that :)
This is the Japanese gift I received.

Group photo On the 16th of September, we had a group photo. I am glad that this year I was more clear in this picture than in DebConf22.
Click to enlarge

Volunteer work and talks attended I attended the training session for the video team and worked as a camera operator. The Bits from DPL was nice. I enjoyed Abhas presentation on home automation. He basically demonstrated how he liberated Internet-enabled home devices. I also liked Kristi s presentation on ways to engage with the GNOME community.
Bits from the DPL. Photo credits: Bilal
Kristi on GNOME community. Photo credits: Ravi Dwivedi.
Abhas' talk on home automation. Photo credits: Ravi Dwivedi.
I also attended lightning talks on the last day. Badri, Wouter, and I gave a demo on how to register on the Prav app. Prav got a fair share of advertising during the last few days.
I was roaming around with a QR code on my T-shirt for downloading Prav.

The night of the 17th of September Suresh left the hotel and Badri joined me in my room. Thanks to the efforts of Abhijit PA, Kiran, and Ananthu, I wore a mundu.
Me in mundu. Picture credits: Abhijith PA
I then joined Kalyani, Mangesh, Ruchika, Anisa, Ananthu and Kiran. We took pictures and this marked the last night of DebConf23.

Departure day The 18th of September was the day of departure. Badri slept in my room and left early morning (06:30 AM). I dropped him off at the hotel gate. The breakfast was at the eatery (3rd floor) again, and it was good. Sahil, Saswata, Nilesh, and I hung out on the ground floor.
From left: Nilesh, Saswata, me, Sahil. Photo credits: Sahil.
I had an 8 PM flight from Kochi to Delhi, for which I took a cab with Rhonda (Austria), Michael (Nigeria) and Yash (India). We were joined by other DebConf23 attendees at the Kochi airport, where we took another selfie.
Ruchika (taking the selfie) and from left to right: Yash, Joost (Netherlands), me, Rhonda
Joost and I were on the same flight, and we sat next to each other. He then took a connecting flight from Delhi to Netherlands, while I went with Yash to the New Delhi Railway Station, where we took our respective trains. I reached home on the morning of the 19th of September, 2023.
Joost and me going to Delhi. Photo credits: Ravi.

Big thanks to the organizers DebConf23 was hard to organize - strict alcohol laws, weird hotel rules, death of a close friend (almost a family member), and a scary notice by the immigration bureau. The people from the team are my close friends and I am proud of them for organizing such a good event. None of this would have been possible without the organizers who put more than a year-long voluntary effort to produce this. In the meanwhile, many of them had organized local events in the time leading up to DebConf. Kudos to them. The organizers also tried their best to get clearance for countries not approved by the ministry. I am also sad that people from China, Kosovo, and Iran could not join. In particular, I feel bad for people from Kosovo who wanted to attend but could not (as India does not consider their passport to be a valid travel document), considering how we Indians were so well-received in their country last year.

Note about myself I am writing this on the 22nd of September, 2023. It took me three days to put up this post - this was one of the tragic and hard posts for me to write. I have literally forced myself to write this. I have still not recovered from the loss of my friend. Thanks a lot to all those who helped me. PS: Credits to contrapunctus for making grammar, phrasing, and capitalization changes.

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