Open-source News

The HID subsystem updates for Linux 6.3 have been submitted and they contain a number of exciting input updates for this spring 2023 kernel version from the introduction of HID-BPF to native Steam Deck controller interface handling...

Linux Operating System Market Growth Research 2023-2027: by ... - Digital Journal

Google News - Wed, 02/22/2023 - 19:53

Linux Operating System Market Growth Research 2023-2027: by ... Digital Journal

Ubuntu Flavors/Spins Will No Longer Be Able To Install Flatpak By Default

Phoronix - Wed, 02/22/2023 - 19:25

While Ubuntu Linux hasn't provided Flatpak support out-of-the-box due to their preference of using their own Snap app packaging/distribution format, Ubuntu flavors/spins have to this point been able to pre-install Flatpak support if they desired. However, for the 23.04 "Lunar Lobster" cycle and moving forward, Ubuntu flavors will no longer be permitted to install Flatpak packages by default...

Ubuntu Flavors/Spins Will No Longer Be Able To Install Flatpak By Default - Phoronix

Google News - Wed, 02/22/2023 - 19:25

Ubuntu Flavors/Spins Will No Longer Be Able To Install Flatpak By Default Phoronix

Tailoring your Linux command prompt - Network World

Google News - Wed, 02/22/2023 - 19:10

Tailoring your Linux command prompt Network World

ARK Logic X.Org Driver Sees 2023 Update For 90's PCI Video Card

Phoronix - Wed, 02/22/2023 - 18:56

A week after seeing X.Org display driver updates for old Trident and S3 Graphics hardware, a new release of xf86-video-ark is now available that provides the open-source UMS display driver support for old ARK Logic hardware. ARK Logic only lasted through the 1990's as a purveyor of PCI video cards...

Computop debuts three new Linux-based payment terminals - Finextra

Google News - Wed, 02/22/2023 - 18:42

Computop debuts three new Linux-based payment terminals Finextra

Linux 6.3 Adds ath12k Driver For Qualcomm WiFi 7 Hardware Support

Phoronix - Wed, 02/22/2023 - 18:41

As part of the Linux networking updates for the Linux 6.3 cycle in addition to the BIG TCP support for IPv4 that can yield higher throughput and lower latency, another networking change worth pointing out is the introduction of the "ath12k" driver for Qualcomm WiFi 7 hardware support...

Linux 6.3 Adds ath12k Driver For Qualcomm WiFi 7 Hardware Support - Phoronix

Google News - Wed, 02/22/2023 - 18:41

Linux 6.3 Adds ath12k Driver For Qualcomm WiFi 7 Hardware Support Phoronix

Linus Torvalds Reacts to Poorly-Executed Pull Requests for Linux 6.3 - It's FOSS News

Google News - Wed, 02/22/2023 - 18:30

Linus Torvalds Reacts to Poorly-Executed Pull Requests for Linux 6.3 It's FOSS News

Microsoft .NET 8 bolsters Linux support - InfoWorld

Google News - Wed, 02/22/2023 - 16:00

Microsoft .NET 8 bolsters Linux support InfoWorld

How I do automated accessibility testing for my website

opensource.com - Wed, 02/22/2023 - 16:00

How I do automated accessibility testing for my website dmundra Wed, 02/22/2023 - 03:00

This article covers adding accessibility tests to your site using Pa11y (pa11y-ci with axe) and Cypress (with cypress-axe) in GitLab CI/CD. I use a Jekyll website as an example, but any website technology that runs in CI/CD can leverage this setup.

Prep your website

In addition to getting your website to run in CI/CD, I recommend enabling an XML sitemap feature. A sitemap allows the accessibility tests to parse all URLs to find accessibility issues across the site. I recommend the jekyll-sitemap plugin for Jekyll sites.

Collecting a list of all major URLs is a good alternate step if a sitemap is not possible. The URLs should cover all potential layouts of the website, such as pages with the highest traffic or the most landings. This approach won't catch all accessibility issues, especially content level concerns, but it will test the layout and main pages.

This scenario requires the npm or yarn package managers. I used npm for this article. If your project doesn't have npm initialized, run the npm init command to create the package.json file.

Begin with Pa11y

Pa11y is a free and open source software that tests websites for accessibility issues. Pa11y-ci is the command line utility geared towards continuous integration (CI). Install pa11y-ci as a development dependency with npm:

$ npm i --save-dev pa11y-ci

After you complete the installation, edit the package.json and add the following commands to the scripts section:

"start-detached": "bundle exec jekyll serve --detach", "pa11y-ci:home": "pa11y-ci http://127.0.0.1:4000", "pa11y-ci:sitemap": "pa11y-ci --sitemap http://127.0.0.1:4000/sitemap.xml --sitemap-find https://accessibility.civicactions.com --sitemap-replace http://127.0.0.1:4000 --sitemap-exclude \"/*.pdf\""

start-detached: Starts the web server that will run Jekyll for testing.
pa11y-ci:home: Runs pa11y-ci tests on the home page. Useful for troubleshooting.
pa11y-ci:sitemap: Runs pa11y-ci tests using the sitemap and excludes PDFs. The sitemap will refer to the live site URLs, so replace those with local URLs for testing in the CI pipeline.

Add a JSON file named .pa11yci that configures pa11y-ci with various options. Here is a sample file:

{ "defaults": { "concurrency": 1, "standard": "WCAG2AA", "runners": ["axe", "htmlcs"], "ignore": [ "color-contrast", "frame-tested" ], "chromeLaunchConfig": { "args": ["--disable-dev-shm-usage", "--no-sandbox", "--disable-gpu"] }, "reporters": [ "cli", ["./pa11y-reporter-junit.js", { "fileName": "./pa11y-report-junit.xml" }] ] } }

concurrency: I reduced this set to 1 because increasing it caused errors (https://github.com/pa11y/pa11y-ci/issues/168 covers the bug, which might be fixed).
standard: I have stuck with the default WCAG2AA as the goal for this site.
runners: I ran axe (run tests using axe-core) and htmlcs (default, run tests using HTML CodeSniffer) to cover all potential accessibility issues.
ignore: With newer versions of axe and some of the changes to the site, I ran into color contrast false positives. I also have an embedded iframe that requires separate testing that axe will report about. I have follow-up issues to examine the axe results, so I am ignoring those criteria for now.
chromeLaunchConfig: pa11y-ci uses Chrome, and I found that the GitLab CI pipeline requires that the Chrome browser runs properly in the pipeline.
reports: I use the default command line reporter, but I also added a custom reporter that reports on the pa11y-ci results in a junit format. This came in handy for reporting the results in the GitLab CI pipeline.

That's it. Run this setup locally using npm, and you will see the following output (truncated for brevity):

dmundra in ~/workspace/accessibility/accessibility on branch main > npm run start-detached > start-detached > bundle exec jekyll serve --detach Configuration file: /Users/dmundra/workspace/accessibility/accessibility/_config.yml Source: /Users/dmundra/workspace/accessibility/accessibility Destination: /Users/dmundra/workspace/accessibility/accessibility/_site Incremental build: disabled. Enable with --incremental Generating... done in 8.217 seconds. Auto-regeneration: disabled when running server detached. Server address: http://127.0.0.1:4000 Server detached with pid '14850'. Run `pkill -f jekyll' or `kill -9 14850' to stop the server. dmundra in ~/workspace/accessibility/accessibility on branch main > npm run pa11y-ci:sitemap > pa11y-ci:sitemap > pa11y-ci --sitemap http://localhost:4000/sitemap.xml --sitemap-exclude "/*.pdf" Running Pa11y on 110 URLs: > http://localhost:4000/guide/glossary - 0 errors > http://localhost:4000/guide/introduction - 0 errors > http://localhost:4000/guide/history - 0 errors > http://localhost:4000/guide/design - 0 errors ... ✔ 110/110 URLs passed

The site passes the tests. Here is an example job running in GitLab. The pa11y configuration continues to test all site pages for accessibility issues and report on them.

What does an error look like? Here is an example:

> http://localhost:4000/guide/introduction - 1 errors Errors in http://localhost:4000/guide/introduction: •

, or elements (https://dequeuniversity.com/rules/axe/3.5/list?application=axeAPI) (#main-content > div:nth-child(2) > div > div > div > div:nth-child(1) > nav > ul)

Mapping the program counter back to the function name in your code

opensource.com - Wed, 02/22/2023 - 16:00

Mapping the program counter back to the function name in your code wcohen Wed, 02/22/2023 - 03:00

Compilers are commonly used to convert human-readable source code into a series of instructions that are directly executed by the computer. A common question is "How do the debuggers and error handlers report the place in the source code where the processor is currently at?" There are various methods to map instructions back to locations in the source code. With the compiler optimizing the code, there are also some complications in mapping the instructions back to the source code. This first article in the series describes how tools map the program counter (also known as the instruction pointer) back to the function name. Subsequent articles in this series will cover mapping the program counter back to the specific line in a source file. It also provides a backtrace describing the series of calls that resulted in the processor being in the current function.

The function entry symbols

When translating source code into an executable binary, the compiler keeps symbol information about the entry to each function. Keeping this information available makes it possible for the linker to assemble multiple object files (.o suffix) into a single executable file. Before the object files are processed by the linker, the final addresses of functions and variables are not known. The object files have placeholders for the symbols that do not yet have addresses. The linker will resolve the addresses when creating the executable. Assuming that the resulting executable is not stripped, those symbols describing the entry of each function are still available. You can see an example of this by compiling the following simple program:

#include #include int a; double b; int main(int argc, char* argv[]) { a = atoi(argv[1]); b = atof(argv[2]); a = a + 1; b = b / 42.0; printf ("a = %d, b = %f\n", a, b); return 0; }

Compile the code:

$ gcc -O2 example.c -o example

You can see where the main function starts at 0x401060 with the following command:

$ nm example |grep main U __libc_start_main@GLIBC_2.34 0000000000401060 T main

Even though the code is compiled without debugging information (-g option), gdb can still find the start of the main function with the symbol information:

$ gdb example GNU gdb (GDB) Fedora 12.1-1.fc36 … (No debugging symbols found in example) (gdb) break main Breakpoint 1 at 0x401060

Step through the code with the GDB nexti command. GDB reports the address it is currently at in the main function:

(gdb) nexti 0x0000000000401061 in main () (gdb) nexti 0x0000000000401065 in main () (gdb) where #0 0x0000000000401065 in main ()

This minimal information is useful but is not ideal. The compiler can optimize functions and split functions into non-contiguous sections to make code associated with the function not obviously tied to the listed function entry. A portion of the function's instructions might be separated from the function entry by other functions' entries. Also, the compiler may generate alternative names that do not directly match the original function names. This makes it more difficult to determine which function in the source code the instructions are associated with.

DWARF information

Code compiled with the -g option includes additional information to map between the source code and the binary executable. By default RPMs with code compiled on Fedora have the debug information generation enabled. Then this information is put into a separate debuginfo RPM, which can be installed as a supplement to the RPMs containing the binaries. This makes it easier to analyze crash dumps and debug programs. With debuginfo, you can get address ranges that map back to particular function names. It also provides the line number and file name that each instruction maps back to. The mapping information is encoded in the DWARF standard.

The DWARF function description

For each function with a function entry there is a DWARF Debug Information Entry (DIE) describing it. This information is in a machine-readable format, but there are a number of tools including llvm-dwarfdump and eu-readelf that produce human-readable output of the DWARF debug information. Below is the llvm-dwarfdump output of the example main function DIE describing the main function of the earlier example.c program.

The DIE starts with the DW_TAG_subprogram to indicate it describes a function. There are other kinds of DWARF tags used to describe other components of programs such as types and variables.

The DIE for the function has multiple attributes each starting with DW_AT_ that describe the characteristics of the function. These attributes provide information about the function, such as where the function is located in the executable binary. It also points where to find it in the original source code.

A few lines down from the DW_TAG_subprogram is the DW_AT_name attribute that describes the source code function name as main. The DW_AT_decl_file and DW_AT_decl_line DWARF attributes describe the file and line number respectively where the function came from. This allows the debugger to find the appropriate location in a file to show you the source code associated with the function. Column information is also included with the DW_AT_decl_column.

The other key pieces of information for mapping between the binary instructions and the source code are the DW_AT_low_pc and DW_AT_high_pc attributes. The use of the DW_AT_low_pc and DW_AT_high_pc indicates that the code for this function is contiguous, ranging from 0x401060 (the same value as provided by nm command earlier) up to but not including 0x4010b7. The DW_AT_ranges attribute is used to describe functions if the function covers non-contiguous regions.

With the program counter, you can map the processor's program counter to the function name and find the file and line number where the function is:

$ llvm-dwarfdump example --name=main example: file format elf64-x86-64 0x00000113: DW_TAG_subprogram DW_AT_external (true) DW_AT_name ("main") DW_AT_decl_file ("/home/wcohen/present/202207youarehere/example.c") DW_AT_decl_line (8) DW_AT_decl_column (0x01) DW_AT_prototyped (true) DW_AT_type (0x00000031 "int") DW_AT_low_pc (0x0000000000401060) DW_AT_high_pc (0x00000000004010b7) DW_AT_frame_base (DW_OP_call_frame_cfa) DW_AT_call_all_calls (true) DW_AT_sibling (0x000001ea)Inlined functions

A compiler can optimize code by replacing a call to another function with instructions that implement the operations of that called function. An inlined function eliminates control flow changes caused by function call and return instructions to implement the traditional function calls. For an inlined function, there is no need for executing additional function prologue and epilogue instructions required to conform to the Application Binary Interface (ABI) of traditional function calls.

Inline functions also provide additional opportunities for optimizations as the compiler can intermix instructions between the caller and the inlined invoked function. This provides a complete picture of what code can safely be eliminated. However, if you just used the address ranges from the real functions described by the DW_TAG_subprogram, then you might misattribute an instruction to the function that called the inlined function, rather than the actual inlined function containing it. For that reason, DWARF has the DW_TAG_inlined_subroutine to provide information about inlined functions.

Surprisingly, even example.c, the simple example provided in this article, has inlined functions in the generated code, atoi and atof. The code block below shows the output of llvm-dwarfdump for atoi. There are two parts, a DW_TAG_inlined_subroutine to describe each place atoi was actually inlined and a DW_TAG_subprogram describing the generic information that does not change between the multiple inlined copies.

The DW_AT_abstract_origin in the DW_TAG_inlined_subroutine points to the associated DW_TAG_subprogram that describes the file with DW_AT_decl_file and DW_AT_decl_line just like a DWARF DIE describing a regular function. In this case, you see that this inlined function is coming from line 362 of system file /usr/include/stdlib.h.

The actual range of addresses that are associated with atof is non-contiguous and described by DW_AT_ranges, [0x401060,0x401060), [0x401061, 0x401065), [0x401068,0x401074), and [0x40107a,0x41080). The DW_TAG_inlined_subroutine has a DW_AT_entry_pc to indicate what location is considered to be the start of the inlined function. With the compiler reordering instructions it may not be obvious what would be considered the first instruction of an inlined function:

$ llvm-dwarfdump example --name=atoi example: file format elf64-x86-64 0x00000159: DW_TAG_inlined_subroutine DW_AT_abstract_origin (0x00000208 "atoi") DW_AT_entry_pc (0x0000000000401060) DW_AT_GNU_entry_view (0x02) DW_AT_ranges (0x0000000c [0x0000000000401060, 0x0000000000401060) [0x0000000000401061, 0x0000000000401065) [0x0000000000401068, 0x0000000000401074) [0x000000000040107a, 0x0000000000401080)) DW_AT_call_file ("/home/wcohen/present/202207youarehere/example.c") DW_AT_call_line (10) DW_AT_call_column (6) DW_AT_sibling (0x00000196) 0x00000208: DW_TAG_subprogram DW_AT_external (true) DW_AT_name ("atoi") DW_AT_decl_file ("/usr/include/stdlib.h") DW_AT_decl_line (362) DW_AT_decl_column (0x01) DW_AT_prototyped (true) DW_AT_type (0x00000031 "int") DW_AT_inline (DW_INL_declared_inlined)

Programming and development Red Hat Developers Blog Programming cheat sheets Try for free: Red Hat Learning Subscription eBook: An introduction to programming with Bash Bash shell scripting cheat sheet eBook: Modernizing Enterprise Java An open source developer's guide to building applications Implications of inline functions

Most programmers think of the processor completely executing one line in the source code before moving on to the next. Similarly, with the expected function call ABI programmers think of where the caller function completes operations in the statements before the call and statements after the call are not started until the callee function return may not hold. With inlined function, the boundaries between functions become fuzzy. Instructions from the caller function may be scheduled before or after the instructions from the inlined functions regardless of where they were in the source code if the compiler determines that the final result will be the same. This may lead to unexpected values when inspecting variables before and after the inlined functions.

UR Solutions News

Linux Foundation Welcomes New Open Source Projects from Peraton Labs to Scale 5G Security - Yahoo Finance

Linux Foundation Welcomes New Open Source Projects from ... - PR Newswire

Intel LKGS, AMD Automatic IBRS & Caching AMD Debug Registers Merged For Linux 6.3

Intel LKGS, AMD Automatic IBRS & Caching AMD Debug Registers Merged For Linux 6.3 - Phoronix

iXsystems Introduces TrueNAS Mini R Appliance with Linux-based ... - insideHPC

Microsoft .NET Runtime Lands Initial Code For RISC-V Support

HID-BPF Ready For Linux 6.3 Along With Steam Deck Controller ... - Phoronix

HID-BPF Ready For Linux 6.3 Along With Steam Deck Controller Interface