Hey Denis, My reply got out of control here. Apologies for the length, feel
free to ignore the top and just skip to my replies. :)
The points you bring up are definitely valid, but coreboot isn't Linux. We
don't have the same infrastructure, or investment from companies. coreboot has
no "full time" contributors as such. We have a number of contributors from
various companies who need to get their products shipped, but they all have
varying amounts of time to spend on the project. It's a tiny tiny fraction of
what Linux gets.
I don't mean to say that coreboot is a small project - we're not. In the past
year, we've gotten contributions from over 350 different people. Most of these
contributions are from people who work on coreboot as a job. Those aren't the
people who keep the project alive though. There are really just a couple of
dozen people at any given time who actually do the work on the coreboot project
outside of the individual patches they're assigned to do for their jobs.
Unfortunately, that's simply not enough people to maintain all of the platforms
and chips in the tree the way things are currently. We could do something like
add a requirement that each platform added needs to donate two (or choose an
arbitrary number) boards to the coreboot project that we install somewhere and
test on a (daily/weekly/monthly) basis to make sure that they're working.
Currently we don't have the funds or a place to do that. It also puts a burden
on an individual who wants to add a board to the coreboot tree. It creates
problems for companies that use coreboot for an embedded system that isn't easy
to test.
Looking forward:
coreboot just got our first "large" donation from Google to support the build
servers for the next year. Until now, the build servers have mainly been
running from my house. We've reached the point where the project can no longer
run as a hobby-project on a hobby-project budget.
If we're going to actually be more than a hobby-project going forward, I think
we're going to need to expand our scope and make changes to the way we do
things. This is going to require making changes to better define how things
like code deprecation is handled.
I think you're right that we need some way to guarantee that boards added to
coreboot aren't going to be dropped again in a short period of time, but that
requires investment from companies using coreboot to make sure that it happens.
When a chip is added to coreboot, how long is a company expected to maintain
that chip in the coreboot repository? If we make it too short, nobody wants to
develop mainboards for it. If we make that time too long, chip vendors aren't
going to want to add their chips to the tree. I'm not sure how to balance that.
Jan 3, 2023, 17:17 by gnu...@cyberdimension.org:
> On Tue, 3 Jan 2023 18:38:02 +0100 (CET)
> Martin Roth <gauml...@tutanota.com> wrote:
>
>> Hi Denis,
>> - Responses inline
>>
> Hi,
>
> Thanks for the answers.
>
>> Jan 2, 2023, 17:16 by gnu...@cyberdimension.org:
>>
>> > Hi,
>> >
>> > The MAINTAINERS file has the following:
>> >
>> >> PC ENGINES ALL MAINBOARDS
>> >> M: Piotr Król <piotr.k...@3mdeb.com>
>> >> M: Michał Żygowski <michal.zygow...@3mdeb.com>
>> >> S: Supported
>> >> F: src/mainboard/pcengines/
>> >>
>> >
>> > But the commit f9decbb0c720662d8e71fe221aef55b7ecf76196 ("mb/*/*:
>> > Remove AMD family14 boards") actually removed the apu1
>> > (src/mainboard/pcengines/).
>> >
>> > Is there some policy somewhere that describes what kind of support
>> > to expect from maintained boards?
>> Yes, It's in the maintainers file itself:
>>
>> Supported: Someone is continuously paid to look after
>> this and a reaction to review requests can be expected
>> within a few days, a month at most.
>>
> [...]
>
>> Because the maintainers may not notice the patches, it's always
>> suggested to reach out to the maintainers directly for reviews.
>>
> As I understand that file tells only about patch review delays and not
> what kind of patches are acceptable or not or who is supposed to do the
> work of converting a board to the newer APIs. I'm mostly interested in
> two last aspects.
>
> For instance as a Linux contributor, I can send a patch to add a
> computer (like a smartphone for instance) or contribute fixes and new
> support to existing drivers, and usually the code gets maintained
> somehow automatically:
> - New patches are required not to break existing code, so they have to
> take care to either keep the compatibility with the old code or
> update it along the way.
>
> Though older code doesn't necessarily benefit from new features (for
> instance, for ARM, if nobody converts old C board code to the
> devicetree, it will still works if people compile support for that
> ARM computer, but the resulting kernel will only be able to boot on
> that computer).
>
> The code quality requirements is usually very high in order to reduce
> the amount of time required to maintain the code.
>
> - If I'd contribute a driver instead, I may end up being its maintainer
> somehow, so I'd have to review patches. Who will maintain the driver
> might also be part of the discussion when upstream will decide or not
> to accept the patch for the new driver.
>
> - Users can test the code and report bugs. If the bugs are reported
> during patch review, the burden to fix the bug is on the person who
> sent the patch.
>
> Since there are different policies in Coreboot, I'm trying to
> understand if it's possible to somehow find ways to get the same kind
> of assurances than with Linux so that specific mainboards will not be
> removed, and if so how to do it, how much resources it requires, etc.
>
We don't currently have any way to make this assurance. It depends on a number
of things. Imagine that there's a mainboard maintainer, but no chipset
maintainer. If the chipset isn't being maintained and is being removed from ToT
because it's not supported and has become problematic, it's not like the
mainboard can stay independently.
As far as the resources needed, that's difficult for me to say. It depends on
the chipset and the changes that are needed.
Remember that the boards that are removed from ToT are not gone. We've created
branches, and the boards that have been removed from ToT can be maintained on
those branches. We have builders set up to test patches pushed to those
branches for that reason. Those boards may not get all of the latest features
automatically, but do they really need all of the latest features? Does the
KGPE-D16 need an eSPI driver? No - it doesn't support eSPI.
Because coreboot is a firmware project, it's very different than something
that's pure software and can be tested easily. If people want to keep the
chipsets and boards on ToT, we need to have people actually working to keep
them there. There are a very few people at coreboot doing a LOT of work to
keep the project running. We can't do everything for every board on our own.
We need other volunteers who own the boards to test them, submit bugs and
patches, and help with the project. Without that, coreboot has no way of even
knowing if a board is actually working.
> If I look at Linux, in the worst case scenario I can look at the number
> of maintainers for a given driver and expect that the maintainers will
> at worse, work full time on reviewing patches, so that can be roughly
> calculated.
>
> There is also information on how to setup automatic test infrastructure
> (for instance with LAVA) so the resources needed for that can also be
> predicted somehow.
>
> Here this interest me because I'm trying to evaluate if it makes sense
> for me and other interested people to contribute big changes to
> Coreboot, for instance by adding back a mainboard like the Asus
> KGPE-D16. If we do a lot of work and that this work is removed right
> after, it's not worth it, so it's best to check beforehand than to have
> some drama if the huge work is removed.
>
> The issue with Coreboot is that I'm unsure if I can do the same kind of
> calculation than with Linux: The APU1 was removed despite the fact that
> the mainboard was "supported".
>
As mentioned in the scenario above, the mainboard was marked as being
supported, but the chipset was not. Unless someone is willing to step up as
the supporter of the chipset, I don't know what to tell you. We can't really
keep the mainboard without the chipset. I don't know if there's something
similar in the linux hierarchy to look at, but if there is, I'd be interested
in knowing how it's handled there.
> So this is why I'm trying to understand how much work it is to convert
> boards and for that understanding how deprecation are decided could
> give me hints of the amount of work to expect in the worst case.
>
>> The usual reason is progress: Infrastructure module X has been
>> replaced byinfrastructure module X+1. Removing X helps keep the
>> sources manageableand likely opens opportunities to improve the
>> codebase even more.
>>
> Here I am wondering precisely how the deprecation of module X is
> decided. For instance can anyone convert some code in Rust and expect
> everybody else to learn Rust and rewrite everything in Rust?
>
> Is it up to maintainers of each module to decide when to deprecate
> module X in favor of module X+1?
>
This is typically suggested on the mailing list, beaten to a pulp, then
discussed in the coreboot leadership meeting for a decision
> If so what are usually the factors taken into account? I assume that if
> there is too much change to do (like completely rewriting Coreboot in
> Rust), I assume that they won't be able to force a change like that on
> the rest of the Coreboot contributors. If that's the case it gives some
> indication of the amount of work required to convert to newer modules.
>
> It also brings the question of what is taken into account when deciding
> to deprecate module X. For instance is the maintainability of each
> "modules" the only concern, or are the amount of supported mainboards
> and end users a concern too?
>
> Is the amount of work needed to convert from module X to module X+1
> taken into account? And is there usually some documentation that
> explains how to do the conversion? Or are do people need to find out by
> looking at the release notes and other boards being converted?
>
We don't currently have a written policy about it.
>> > Is there also a policy that explains when boards are removed? Or
>> > what to do to prevent boards from being removed?
>> >
>> We do have that policy, though it could probably be written a bit
>> more plainly.
>>
>> Here's the search in the coreboot documentation.
>> https://doc.coreboot.org/search.html?q=deprecation&check_keywords=yes&area=default
>>
>> Here's the template for the release notes:
>>
>> Deprecation notices are part of release notes to act as a warning: at
>> somepoint in the future some part of coreboot gets removed. That
>> point must beat least 6 months after the release of the notice and it
>> must be right aftersome release: That is, the specified release must
>> still contain the part inquestion while one git commit later it might
>> be removed.
>>
> That is good: at least we have a way to find that out.
>
>> > For instance u-boot warns when building that a boards needs to be
>> > adjusted to the newer driver model. So just by building u-boot you
>> > know in advance what needs to be fixed and for when.
>> >
>> > I've looked in the Coreboot documentation but I didn't find any
>> > information about that.
>> >
>>
>> Someone could definitely add something to put up a notice when doing
>> the build, but that doesn't exist right now. If it's not something
>> that you're interested in doing, you could file a bug if you think it
>> should be added.`
>>
> I'm not sure I'm the right person to do that, and if so how I could do
> it. I could probably propose a patch to the documentation though, if
> it's the right place to do it.
>
> For the code, it's probably best if it's done in the commit that
> deprecates something. For instance for CONFIG_LEGACY_SMP_INIT, we could
> add the following to the Makefile in the top directory:
>
> ifneq ($(CONFIG_LEGACY_SMP_INIT),)
> @echo "+----------------------- /!\ WARNING /!\ ---------------------+"
> @echo "| CONFIG_LEGACY_SMP_INIT is deprecated. |"
> @echo "| It will be removed in Coreboot release 4.18 (November 2022).|"
> @echo "| Please migrate your mainboard to CONFIG_PARALLEL_MP, |"
> @echo "| or it will be removed right after the Coreboot 4.18 release.|"
> @echo "| See the Coreboot release notes[1] for more details. |"
> @echo "| [1]Documentation/releases/coreboot-4.16-relnotes.md |"
> @echo "+-------------------------------------------------------------+"
> endif
>
> If we add that at the end of the Makefile, to have it show up at the
> end of the build. We could also add a deprecation target if needed.
> This way if we do that and that we use a similar format for all
> deprecations, people building Coreboot will most likely see it.
>
> This way users will not have to read all the release notes at each
> releases to catch that kind of issues, and if distributions start
> packaging coreboot or other projects based on Coreboot, then they would
> see that too.
>
I'm all in favor of that. I'll add it to the discussion of the coreboot
leadership meeting on the 11th.
Martin
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