pudc - A PID 1 process that barks to the internet by mssola

Description

As a fun exercise in order to dig deeper into the Linux kernel, its interfaces, the RISC-V architecture, and all the dragons in between; I'm building a blog site cooked like this:

• The backend is written in a mixture of C and RISC-V assembly.
• The backend is actually PID1 (for real, not within a container).
• We poll and parse incoming HTTP requests ourselves.
• The frontend is a mere HTML page with htmx.

The project is meant to be Linux-specific, so I'm going to use io_uring, pidfs, namespaces, and Linux-specific features in order to drive all of this.

I'm open for suggestions and so on, but this is meant to be a solo project, as this is more of a learning exercise for me than anything else.

Goals

• Have a better understanding of different Linux features from user space down to the kernel internals.
• Most importantly: have fun.

Resources

• https://github.com/mssola/pudc

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Create openSUSE images for Arm and RISC-V boards by avicenzi

Project Description

Create openSUSE images (or test generic EFI images) for Arm and RISC-V boards that are not yet supported.

Goal for Hackweek

Create bootable images of Tumbleweed for SBCs that currently have no images available or are untested.

Consider generic EFI images where possible, as some boards can hold a bootloader.

Document in the openSUSE Wiki how to flash and use the image for a given board.

Hack Week 25

• Raspberry Pi 5
• Lichee RV
• Milk-V Jupiter
• SiFive HiFive Premier P550
• SiFive HiFive Unmatched Rev B

Hack Week 24

Hack Week 23

• SiFive HiFive Unmatched

Hack Week 22

• NanoPC T4

Hack Week 21

• NanoPi M4B
• Radxa Zero

Resources

• openSUSE Arm Portal
• openSUSE RISC-V Portal
• SiFive Development Boards
• Raspberry Pi 5

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pudc - A PID 1 process that barks to the internet by mssola

Description

As a fun exercise in order to dig deeper into the Linux kernel, its interfaces, the RISC-V architecture, and all the dragons in between; I'm building a blog site cooked like this:

• The backend is written in a mixture of C and RISC-V assembly.
• The backend is actually PID1 (for real, not within a container).
• We poll and parse incoming HTTP requests ourselves.
• The frontend is a mere HTML page with htmx.

The project is meant to be Linux-specific, so I'm going to use io_uring, pidfs, namespaces, and Linux-specific features in order to drive all of this.

I'm open for suggestions and so on, but this is meant to be a solo project, as this is more of a learning exercise for me than anything else.

Goals

• Have a better understanding of different Linux features from user space down to the kernel internals.
• Most importantly: have fun.

Resources

• https://github.com/mssola/pudc

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Tumbleweed on Mars-CM (RISC-V board) by ph03nix

RISC-V is awesome, Tumbleweed is awesome, chocolate cake is awesome. I'm planning to combine all of them in one project.

Project Description

I recently purchased a MILK-V Mars CM and managed to setup it up already using Debian Linux. My project for this Hackweek is to see how far I can get to run Tumbleweed on this compute module board.

Goal for this Hackweek

• Run Tumbleweed on the Compute Module

Resources

• http://milkv.io/mars-cm
• https://en.opensuse.org/HCL:VisionFive2

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Reassess HiFive Premier P550 board (for RISC-V virtualization) by a_faerber

Description

With growing interest in the RISC-V instruction set architecture, we need to re-evaluate ways of building packages for it:

Currently openSUSE OBS is using x86_64 build workers, using QEMU userspace-level (syscall) emulation inside KVM VMs. Occasionally this setup causes build failures, due to timing differences or incomplete emulation. Andreas Schwab and others have collected workarounds in projects like openSUSE:Factory:RISCV to deal with some of those issues.

Ideally we would be using native riscv64 KVM VMs instead. This requires CPUs with the H extension. Two generally available development boards feature the ESWIN 7700X System-on-Chip with SiFive P550 CPUs, HiFive Premier P550 and Milk-V Megrez. We've had access to the HiFive Premier P550 for some time now, but the early version (based on Yocto) had issues with the bootloader, and reportedly later boards were booting to a dracut emergency shell for lack of block device drivers.

Goals

• Update the boot firmware
• Test whether and how far openSUSE Tumbleweed boots

Results

• Boot firmware image 2025.11.00 successfully flashed onto board
  • Enables UEFI boot in U-Boot by default
  • U-Boot's embedded Flat Device Tree is lacking a timebase-frequency, required for recent (6.16.3) mainline kernels (panic leading to reset, visible via earlycon=sbi)
• Tested eswin/eic7700-hifive-premier-p550.dtb from Ubuntu 2025.11.00 image
  • Allows to boot past the above panic, but times out in JeOS image while waiting for block device, dropping to dracut emergency shell
  • No devices shown in lsblk -- 6.16 appears to be lacking device drivers still

Resources

• SiFive HiFive Premier P550 board
• Milk-V Megrez board

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Port OTPClient to GTK >= 4.18 by pstivanin

Project Description

OTPClient is currently using GTK3 and cannot easily be ported to GTK4. Since GTK4 came out, there have been quite some big changes. Also, there are now some new deprecation that will take effect with GTK5 (and are active starting from 4.10 as warnings), so I need to think ahead and port OTPClient without using any of those deprecated features.

Goal for this Hackweek

• fix the last 3 opened issues (https://github.com/paolostivanin/OTPClient/issues/402, https://github.com/paolostivanin/OTPClient/issues/404, https://github.com/paolostivanin/OTPClient/issues/406) and release a new version
• continue the rewrite from where we left last year
• if possible, finally close this 6 years old issue: https://github.com/paolostivanin/OTPClient/issues/123

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x64id: An x86/x64 instruction disassembler by m.crivellari

Description

This is an old side project. An x86/x64 machine code decoder. It is useful to get instructions' length and identify each of its fields.

Example:

C7 85 68 FF FF FF 00 00 00 00

This is the instruction:

MOV DWORD PTR SS:[LOCAL.38],0

What follows are some of the information collected by the disassembler, based on the specific instruction:

RAW bytes (hex): C7 85 68 FF FF FF 00 00 00 00
Instr. length: 10
Print instruction fields:
        Located Prefixes 0:

        OP: 0xC7
        mod_reg_rm: 0x85
        disp (4): 0xFFFFFF68
        Iimm: 0x0

Lacks the mnemonic representation: from the previous machine code is not able to produce the "MOV..." instruction, for example.

Goals

The goal is almost easy: partially implement the mnemonic representation. I have already started during the weekend, likely tomorrow I will push the branch!

Resources

• The project: https://github.com/DispatchCode/x64-Instruction-Decoder/
• This is useful to avoid gdb and objdump in local: https://defuse.ca/online-x86-assembler.htm
• Another interesting resource is https://godbolt.org/

Progress

• An initial implementation can be found at: https://github.com/DispatchCode/x64-Instruction-Decoder/tree/mnemonic-support It is described under the "Mnemonic translation" in the README file!

Let's consider this example:

[...other bytes...] 43 89 44 B5 00 01 00 [...other bytes...]

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Improve the picotm Transaction Manager by tdz

Picotm is a system-level transaction manager. It provides transactional semantics to low-level C operations, such as

• memory access,
• modifying data structures,
• (some) file I/O, and
• common interfaces from the C Standard Library and POSIX.

Picotm also handles error detection and recovery for all it's functionality. It's fully modular, so new functionality can be added.

For the Hackweek, I want to dedicate some time to picotm. I want to finish some of the refactoring work that I have been working on. If there's time left, I'd like to investigate two-phase commits and how to support them in picotm.

Picotm is available at http://picotm.org/.

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pudc - A PID 1 process that barks to the internet by mssola

Description

As a fun exercise in order to dig deeper into the Linux kernel, its interfaces, the RISC-V architecture, and all the dragons in between; I'm building a blog site cooked like this:

• The backend is written in a mixture of C and RISC-V assembly.
• The backend is actually PID1 (for real, not within a container).
• We poll and parse incoming HTTP requests ourselves.
• The frontend is a mere HTML page with htmx.

The project is meant to be Linux-specific, so I'm going to use io_uring, pidfs, namespaces, and Linux-specific features in order to drive all of this.

I'm open for suggestions and so on, but this is meant to be a solo project, as this is more of a learning exercise for me than anything else.

Goals

• Have a better understanding of different Linux features from user space down to the kernel internals.
• Most importantly: have fun.

Resources

• https://github.com/mssola/pudc

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Add a machine-readable output to dmidecode by jdelvare

Description

There have been repeated requests for a machine-friendly dmidecode output over the last decade. During Hack Week 19, 5 years ago, I prepared the code to support alternative output formats, but didn't have the time to go further. Last year, Jiri Hnidek from Red Hat Linux posted a proof-of-concept implementation to add JSON output support. This is a fairly large pull request which needs to be carefully reviewed and tested.

Goals

Review Jiri's work and provide constructive feedback. Merge the code if acceptable. Evaluate the costs and benefits of using a library such as json-c.

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pudc - A PID 1 process that barks to the internet by mssola

Description

As a fun exercise in order to dig deeper into the Linux kernel, its interfaces, the RISC-V architecture, and all the dragons in between; I'm building a blog site cooked like this:

• The backend is written in a mixture of C and RISC-V assembly.
• The backend is actually PID1 (for real, not within a container).
• We poll and parse incoming HTTP requests ourselves.
• The frontend is a mere HTML page with htmx.

The project is meant to be Linux-specific, so I'm going to use io_uring, pidfs, namespaces, and Linux-specific features in order to drive all of this.

I'm open for suggestions and so on, but this is meant to be a solo project, as this is more of a learning exercise for me than anything else.

Goals

• Have a better understanding of different Linux features from user space down to the kernel internals.
• Most importantly: have fun.

Resources

• https://github.com/mssola/pudc

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Improve UML page fault handler by ptesarik

Description

Improve UML handling of segmentation faults in kernel mode. Although such page faults are generally caused by a kernel bug, it is annoying if they cause an infinite loop, or panic the kernel. More importantly, a robust implementation allows to write KUnit tests for various guard pages, preventing potential kernel self-protection regressions.

Goals

Convert the UML page fault handler to use oops_* helpers, go through a few review rounds and finally get my patch series merged in 6.14.

Resources

Wrong initial attempt: https://lore.kernel.org/lkml/20231215121431.680-1-petrtesarik@huaweicloud.com/T/

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Add Qualcomm Snapdragon 765G (SM7250) basic device tree to mainline linux kernel by pvorel

Qualcomm Snapdragon 765G (SM7250) (smartphone SoC) has no support in the linux kernel, nor in u-boot. Try to add basic device tree support. The hardest part will be to create boot.img which will be accepted by phone.

UART is available for smartphone :).

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early stage kdump support by mbrugger

Project Description

When we experience a early boot crash, we are not able to analyze the kernel dump, as user-space wasn't able to load the crash system. The idea is to make the crash system compiled into the host kernel (think of initramfs) so that we can create a kernel dump really early in the boot process.

Goal for the Hackweeks

1. Investigate if this is possible and the implications it would have (done in HW21)
2. Hack up a PoC (done in HW22 and HW23)
3. Prepare RFC series (giving it's only one week, we are entering wishful thinking territory here).

update HW23

• I was able to include the crash kernel into the kernel Image.
• I'll need to find a way to load that from init/main.c:start_kernel() probably after kcsan_init()
• I workaround for a smoke test was to hack kexec_file_load() systemcall which has two problems:
  1. My initramfs in the porduction kernel does not have a new enough kexec version, that's not a blocker but where the week ended
  2. As the crash kernel is part of init.data it will be already stale once I can call kexec_file_load() from user-space.

The solution is probably to rewrite the POC so that the invocation can be done from init.text (that's my theory) but I'm not sure if I can reuse the kexec infrastructure in the kernel from there, which I rely on heavily.

update HW24

• Day1
  • rebased on v6.12 with no problems others then me breaking the config
  • setting up a new compilation and qemu/virtme env
  • getting desperate as nothing works that used to work
• Day 2
  • getting to call the invocation of loading the early kernel from __init after kcsan_init()

• Day 3

  • fix problem of memdup not being able to alloc so much memory... use 64K page sizes for now
  • code refactoring
  • I'm now able to load the crash kernel
  • When using virtme I can boot into the crash kernel, also it doesn't boot completely (major milestone!), crash in elfcorehdr_read_notes()

• Day 4

  • crash systems crashes (no pun intended) in copy_old_mempage() link; will need to understand elfcorehdr...
  • call path vmcore_init() -> parse_crash_elf_headers() -> elfcorehdr_read() -> read_from_oldmem() -> copy_oldmem_page() -> copy_to_iter()

• Day 5

  • hacking arch/arm64/kernel/crash_dump.c:copy_old_mempage() to see if crash system really starts. It does.
  • fun fact: retested with more reserved memory and with UEFI FW, host kernel crashes in init but directly starts the crash kernel, so it works (somehow) \o/

update HW25

• Day 1
  • rebased crash-kernel on v6.12.59 (for now), still crashing

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bpftrace contribution by mkoutny

Description

bpftrace is a great tool, no need to sing odes to it here. It can access any kernel data and process them in real time. It provides helpers for some common Linux kernel structures but not all.

Goals

• set up bpftrace toolchain
• learn about bpftrace implementation and internals
• implement support for percpu_counters
• look into some of the first issues
• send a refined PR (on Thu)

Resources

• https://bpftrace.org/
• https://docs.kernel.org/

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