Jarkko Sakkinen
Posts
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491OpenPGP: 3AB05486C7752FE1
@Conan_Kudo @wtay So the other problem is racy /dev/videoX instance. The problem is in that state changes of the video device are racy by definition. That is obviously unacceptable.
I.e. probably APi should be something along lines of:
1. fd = open("/dev/video_loop")
2. ioctl(fd, "set properties")
2. ioctl(fd, "create")
And post that anything that the device is written goes through that fd and is tied to its life-cycle. That is the only way to guarantee that it is tied to life-cycle of the device per se. Only when the fd is written nothing ever happens in the state of /dev/videoX.
For testing a tool is needed for "capture devices", which will create something for ffmepg to write to so that another ffmpeg instance can play it from /dev/videoX.
I.e. probably APi should be something along lines of:
1. fd = open("/dev/video_loop")
2. ioctl(fd, "set properties")
2. ioctl(fd, "create")
And post that anything that the device is written goes through that fd and is tied to its life-cycle. That is the only way to guarantee that it is tied to life-cycle of the device per se. Only when the fd is written nothing ever happens in the state of /dev/videoX.
For testing a tool is needed for "capture devices", which will create something for ffmepg to write to so that another ffmpeg instance can play it from /dev/videoX.
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Jarkko Sakkinen
jarkko
@Conan_Kudo @wtay
OK, so I think what goes wrong in high-level in the OOT driver and its uapi goes in core essence into: if you provide a service, you DO NOT use the client API to implement your service. Just basic API bullshit, overall, not like in kernel particular...
So instead when you open an fd then "you are /dev/videoX" or whatever. I.e. write ops go to the fd not any of /dev/videoX.
So... based on these it's a fuse alike driver for webcams. There really should maybe one /dev/video_loop device or whatever is a good name , and when you open that file, the creation of that file implies the creation of /dev/videoX.
After that the fd interface in user space gives all data and meta-data that you could expect similar devices.
So I think this is the gist of getting it wrong in uapi in that driver. But yeah like internals and thinking went on those can be quite easlily refactored out and wrapped in a nicer API package.
So yeah I'll do what I do put this in clean shape and send RFC patch set. So can CC obviously people to that once I get it out (few weeks smthng).
OK, so I think what goes wrong in high-level in the OOT driver and its uapi goes in core essence into: if you provide a service, you DO NOT use the client API to implement your service. Just basic API bullshit, overall, not like in kernel particular...
So instead when you open an fd then "you are /dev/videoX" or whatever. I.e. write ops go to the fd not any of /dev/videoX.
So... based on these it's a fuse alike driver for webcams. There really should maybe one /dev/video_loop device or whatever is a good name , and when you open that file, the creation of that file implies the creation of /dev/videoX.
After that the fd interface in user space gives all data and meta-data that you could expect similar devices.
So I think this is the gist of getting it wrong in uapi in that driver. But yeah like internals and thinking went on those can be quite easlily refactored out and wrapped in a nicer API package.
So yeah I'll do what I do put this in clean shape and send RFC patch set. So can CC obviously people to that once I get it out (few weeks smthng).
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Jarkko Sakkinen
jarkko
I have a dev-tree: https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/log/?h=v4l2-loopback-dev
1. Suck inner guts out of the OOT driver.
2. Wrap it up tpm_vtpm_proxy
So generally looking for advice on:
1. #Pipewire interaction
2. #Gstreamer interaction
Focus on what instead of how. I.e. if this existed how would uapi play for those upstream projects?
#linux #kernel #video4linux #webcam
1. Suck inner guts out of the OOT driver.
2. Wrap it up tpm_vtpm_proxy
So generally looking for advice on:
1. #Pipewire interaction
2. #Gstreamer interaction
Focus on what instead of how. I.e. if this existed how would uapi play for those upstream projects?
#linux #kernel #video4linux #webcam
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@pavel @vbabka i've tried to give feedback in some reviews to make sure that test script would be busybox ash (i.e. #!/usr/bin/env sh) compatible but some others have downplayed that feedback ;-) at least i've tried...
especially with preproduction hardware it is not uncommon start with fpga so it would somewhat feasible to reduce image size for kernel + kselftest... because loading is SLOW
especially with preproduction hardware it is not uncommon start with fpga so it would somewhat feasible to reduce image size for kernel + kselftest... because loading is SLOW
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Jarkko Sakkinen
jarkko
@Aissen yeah that is what I'm doing small iteration at a time :-) i've read my joel on software in the distant past https://www.joelonsoftware.com/2000/04/06/things-you-should-never-do-part-i/
non taken! and my rants neither should be taken too seriously. i'm basically and idiot trying to find idiomatic patterns :-)
non taken! and my rants neither should be taken too seriously. i'm basically and idiot trying to find idiomatic patterns :-)
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Jarkko Sakkinen
repeated
repeated
Dare Obasanjo
carnage4life@mas.toThis is like something out of medieval king’s court converted into a tweet.
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Jarkko Sakkinen
jarkko
Edited 11 months ago
Well, I heard someone working in game industry that the figures I get with Rust when compiling and linking are in par with C++ projects :-) Like compiling Unreal Engine for instance.
Based on Unreal Engine figures 9950X(3D) should be a decent CPU so with "matching" parts on non-ECC memory (with ThreadRipper I'd actually go with ECC memory), we are talking about 4k investment so be it.
Based on Unreal Engine figures 9950X(3D) should be a decent CPU so with "matching" parts on non-ECC memory (with ThreadRipper I'd actually go with ECC memory), we are talking about 4k investment so be it.
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Jarkko Sakkinen
jarkko
@litchipi Yeah, actually it is the linking that is nasty given the build artifacts that Rust makes but yeah you have a point :-) This was mostly just my stupid ranting that helps me to get over the work day stress, that's the weight of this nonsense really :-)
This goes to non-scientific speculation at best but I'd figure that over the time more innovation will be done for the linking phase as you could probably take advantage (in caching) of the heuristics of the linking phase (blobs build a huge static blob) perhaps... Perhaps even doing some of the compiler backend work specifically targeted to Rust.
This goes to non-scientific speculation at best but I'd figure that over the time more innovation will be done for the linking phase as you could probably take advantage (in caching) of the heuristics of the linking phase (blobs build a huge static blob) perhaps... Perhaps even doing some of the compiler backend work specifically targeted to Rust.
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Jarkko Sakkinen
jarkko
This is literally my certificate of ownership for my downtown apartment in Tampere, Finland. I'd call this a proper stock :-) Especially love the tape fix in the middle.
Still I'm now looking into putting my place to digital register and hang this to my wall...
Still I'm now looking into putting my place to digital register and hang this to my wall...
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Jarkko Sakkinen
jarkko
@raven667 yeah, so no apologies needed. I think you got the post right, I was not 100% dead serious with the post in the first place :-) Sometimes you need to do posts like this just for ranting and blow some steam out of your system... Especially on stuff that you need confront at your work on daily basis...
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@raven667 Also, I think your points are fair :-) Not necessarily disagreeing.
Zed has been BTW a great help browsing large projects. I don't know how its LSP engine is exactly implemented but it is probably caching the JSON data somehow. It can show immediately errors, warnings etc based on data and then it refreshes that. E.g. with my Thinkpad it helps a lot :-)
Zed has been BTW a great help browsing large projects. I don't know how its LSP engine is exactly implemented but it is probably caching the JSON data somehow. It can show immediately errors, warnings etc based on data and then it refreshes that. E.g. with my Thinkpad it helps a lot :-)
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