Jarkko Sakkinen
Posts
4213Following
299Followers
438Entrepreneur at Siltakatu Solutions Oy
OpenPGP: 3AB05486C7752FE1
@phoenix There's every single year employees of Meta, Google and Microsoft giving talks at FOSDEM. Why do you allow that to happen? :-)
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Jarkko Sakkinen
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masukomi
masukomi@connectified.comhow an interns attempts to familiarize themselves with a codebase, and spice up the comments resulting in finding a major security vulnerability. Via Reddit, via 🤷♀️
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Jarkko Sakkinen
jarkko
One more existential reason for v4l2-loopback: testing video4linux features other than v4l2-loopback.
It is always nice to have a module in the stack that can pretend to be a piece of hardware in various end-to-end tests.
Just writing these down so that I can make a credible cover letter at the time :-)
I did this one big refactor few days ago: https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/commit/?h=v4l2-loopback&id=ccb1b6e1247887be17bf22b3809c50848e87a4db
I'm still editing it up until I'm happy with capture/output separation and some other things related (e.g. life-cycle and removal).
Obviously once I sent a patch set I will squash everything before sending...
#video4linux #linux #kernel #media
It is always nice to have a module in the stack that can pretend to be a piece of hardware in various end-to-end tests.
Just writing these down so that I can make a credible cover letter at the time :-)
I did this one big refactor few days ago: https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/commit/?h=v4l2-loopback&id=ccb1b6e1247887be17bf22b3809c50848e87a4db
I'm still editing it up until I'm happy with capture/output separation and some other things related (e.g. life-cycle and removal).
Obviously once I sent a patch set I will squash everything before sending...
#video4linux #linux #kernel #media
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Jarkko Sakkinen
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Thorsten Leemhuis (acct. 1/4)
kernellogger@fosstodon.orgDesigning Custom #Linux Schedulers with sched_ext – slides and the recording of yesterdays #LinuxFoundation Mentorship session from @arighi are now online:
https://www.linuxfoundation.org/webinars/designing-custom-linux-schedulers-with-sched_ext
Direct link to the slides: https://events.linuxfoundation.org/wp-content/uploads/2025/01/Andrea-Righi-Mentorship-1_22_25-scx.pdf
Direct link to the recording: https://www.youtube.com/watch?v=jsLjg9tGuVI
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Jarkko Sakkinen
jarkko
Edited 1 month ago
I've talked to my colleagues that one thing that strikes me in presentations given about any blockchain technology, is that they have a problem that the presentation goes straight into cryptography and smart contracts.
What you *actually* should start with is how the network discovery works. I.e. plain and simple how network nodes find each other. It's not flashy but it is like the first question for any seasoned engineer.
In order to do the secret handshakes you need to first bump into someone else to do your dance.
What you *actually* should start with is how the network discovery works. I.e. plain and simple how network nodes find each other. It's not flashy but it is like the first question for any seasoned engineer.
In order to do the secret handshakes you need to first bump into someone else to do your dance.
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@cesarb @pid_eins Also even if all those procedure were taken care of (rescue password locked into PCR's), I would never use a computer, which has been physically compromised. A physical compromise is a game over as far as I'm concerned, and TPM's work best against software attacks :-) That has been the driving design goal in the standard.
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Jarkko Sakkinen
jarkko
Edited 1 month ago
Multiple capture/output devices issue in the OOT driver and v4l2-loopback. It has the unfinished "SPLIT_DEVICES" compilation options, which I DO NOT fully cope with. I don't get what the heck they are aiming for TBH.
A video device can be either something like camera or something that takes input from client and displays that, e.g. similar device to ChromeCast would be a good example in this context.
I'm aligning to a solution where the initial "ADD" ioctl has:
1. flags (for setting the RW properties)
2. video_nr
3. video_fd (for server to read OR write)
And the direction is determined by flags. I did not fully understand why OOT driver aimed to do both capture and output device simultaneously, which does bother me a bit since it would be best to know the original reasoning, even if the conclusions were wrong.
Moving slowly in this area still and experimenting with options.
#linux #kernel #media #video4linux
A video device can be either something like camera or something that takes input from client and displays that, e.g. similar device to ChromeCast would be a good example in this context.
I'm aligning to a solution where the initial "ADD" ioctl has:
1. flags (for setting the RW properties)
2. video_nr
3. video_fd (for server to read OR write)
And the direction is determined by flags. I did not fully understand why OOT driver aimed to do both capture and output device simultaneously, which does bother me a bit since it would be best to know the original reasoning, even if the conclusions were wrong.
Moving slowly in this area still and experimenting with options.
#linux #kernel #media #video4linux
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- The first API breaking change: https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/commit/?h=v4l2-loopback&id=64dd521682c305567ffa99929a09e2ba285be52e
- The reflective test change: https://codeberg.org/jarkko/v4l2-loopback-test/commit/436818003b9865a9a4af2d872bd09acae84c178e
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Jarkko Sakkinen
jarkkoAt least something done in the kernel side for the v4l2-loopback driver this week:
- The first baby step towards anonymous inode based loopback device: https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/commit/?h=v4l2-loopback&id=90235ae07630962e6dc7c6b2b67f9e94584a6b74
- And a reflective step in my test program: https://codeberg.org/jarkko/v4l2-loopback-test/commit/8950e975817e9d9b8012880dd9f2443d2fe13c77
The next small push is to split v4l2_loopback_fops into two: one for /dev/videoX and other for the anonymous inode returned back from the ioctl.
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Jarkko Sakkinen
jarkko
Edited 1 month ago
Got tired of updating clangd data manually so did a quick script to automate it :
#!/usr/bin/env bash
# Copyright (c) Jarkko Sakkinen 2025
set -e
run_build() {
make ARCH=x86_64 O=.clangd -j$(nproc)
scripts/clang-tools/gen_compile_commands.py -d .clangd
}
run_menuconfig() {
if [[ ! -d .clangd ]]; then
exit 1
fi
make ARCH=x86_64 O=.clangd menuconfig
run_build
}
while getopts ":m" opt; do
case $opt in
m)
run_menuconfig
exit 0
;;
*)
echo "Usage: $0 [-m]"
exit 1
;;
esac
done
if [[ ! -d .clangd ]]; then
make ARCH=x86_64 O=.clangd tinyconfig
fi
run_build
Jarkko Sakkinen
jarkko
Reported to rust-lang/rust if anything to get some ideas how to fix this in the downstream:
https://github.com/rust-lang/rust/issues/135704
It's weird...
#rust #rustlang
https://github.com/rust-lang/rust/issues/135704
It's weird...
#rust #rustlang
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