On 19/03/2025 23:10, Sam James wrote:
Nowa Ammerlaan <n...@gentoo.org> writes:
On 19/03/2025 02:07, Ionen Wolkens wrote:
On Tue, Mar 18, 2025 at 08:34:43PM -0400, Ionen Wolkens wrote:
On Tue, Mar 18, 2025 at 03:14:13AM -0000, Duncan wrote:
Nowa Ammerlaan posted on Mon, 17 Mar 2025 11:11:06 +0100 as excerpted:
I had really hoped to receive more comments on my earlier RFC. [...]
I really do want to know what others think so I can
make a better judgment on whether or not my idea is really this crazy
and if I should just shut up about it or not (so dear reader if you have
an opinion then please share).
So because I carried over my own already "works for me" kernel maintenance
scripts from Mandrake when I switched in 2004 and have continued
maintaining and using them over the decades since, I normally try to stay
out of Gentoo kernel packaging discussion. But given both the above
explicit invitation and that as I've read the thread a thought occurred to
me...
First, DKMS /is/ a cross-distro standard solution. As such, I believe in
general it should be reasonably supported in Gentoo unless it simply
doesn't make sense (note that "doesn't make sense" can also include the
case of simply no one stepping up to do it, not the case here).
But, the thought that occurred to me reading the thread, was that there
are obvious parallels between this and another very significant and
controversial now "cross distro standard solution" (which I guess I don't
need to name explicitly).
As there, I believe "the Gentoo approach" should (again assuming developer
willingness to do the work, seemingly the case here) make it available as
an additional integrated *option*, while keeping the current Gentoo option
as well.
So I support DKMS integration /as/ /an/ /option/.
If anything, if go forward with this, I'd rather that it be with the
plan to (eventually) either make it the default after enough testing
and then later drop support for the old way entirely (then merge the
eclasses), or revert if we think it's no good.
As I have already stated elsewhere, DKMS can do things that we cannot
achieve with the package manager, and the package manager can do
things that we cannot achieve with DKMS. Each pathway has its use
cases. And for that reason DKMS is not a replacement for the package
manager. Nor can I think of a possible future package manager based
solution that can fully replace what DKMS does (though who knows,
maybe someone will prove me wrong in 20 years)
This dual-approach is not controversial either, other distributions
often offer a "normal" package as well as a DKMS package. Now since we
have USE flags we do not have to make two separate packages, but
nonetheless the core of letting the user choose to use DKMS or not
remains the same.
One of the thing I did not like here is the idea to gain more ways
to do the same thing that need to be tested to ensure some quality.
Can't ignore it and leave it all to Nowa given if e.g. nvidia changes
some path or something else and I don't test it on bump, then I push
a broken package for all dkms users until someone reports it. Would
even need to boot with it to be sure.
I'll grant that you'd indeed have to test both USE=dkms and USE=-dkms,
especially if the ebuild does not use a modlist and therefore the
dkms.conf is not constructed fully automatically. Though I do not see
why this would require actually rebooting the system for both
cases. DKMS either builds and installs the module successfully in
postinst or it does not. And regardless of who did the module
installing, it either loads successfully or it does not. Note that we
are intentionally using the exact same commands to actually build the
module in DKMS.
If we're doing it orphaned, it should be done as hooks instead rather
than with any integration in the ebuild, though. postinst / orphaned
files are broadly a hack. Orphaned files break a bunch of invariants
including Just Working for binpkgs properly.
I'm sorry but this does not make any sense to me. What is orphaned here?
The module sources are owned by the package (installed in src_install),
the only thing that is not owned by the package is the built kernel
module itself. And, by design, this is already effectively orphaned
since the package manager does not remove files from /lib/modules
anyway. I don't see how my proposal is orphaning more files.
I also agree with Ionen that this is important enough that I'd want this
to be the primary path (and fully tested & supported), not done at
all. But wanting to support *both* long-time makes me uneasy.
[...]
It's nice to have choices in general, but still need to draw some
lines to keep things maintainable.
This maintainability argument would be a lot stronger if I was
reinventing the wheel and proposing some custom Gentoo specific
solution to the problem at hand. Note though that this is not what I
am doing (in fact one could even turn that around and say that this is
what you are doing). You are of course right that more options means
more things to test. But really, it's not a lot of work, I know
because I did the work for almost all of the kernel module ebuilds we
have in ::gentoo and was finished in half a day. The bulk of the work
was designing and writing the eclass and figuring out all the
different cases that should be supported, that part is done now.
But none of this does feel particularly native to Gentoo. Most of the
Linux world is of binary distros, so while it may not be NIH, it
somewhat is NIH wrt source distros (or can feel like that).
Can you explain to me what exactly about DKMS makes you feel like it is
not for Gentoo? I do not share this feeling and I am having a hard time
wrapping my head around it. As I already said elsewhere, binary distros
(e.g. Arch) can and do offer *both* prebuilt packages *and* dkms source
packages. So evidently binary distros do not have to use DKMS if they do
not want to, though many choose to because it is convenient. This
convenience of dynamically managing the kernel modules instead of
statically applies to Gentoo just as much as it does to other
distributions. It has absolutely nothing to do with the package manager
being able to build from source itself or not.
It is inherent to the nature of the kernel modules that they will have
to be built from source (by the user or the packager) targeting a
specific kernel version. All I am changing here is *when* the module is
built and installed (dynamically versus statically). And I believe this
choice of when the module is built should be left to the user (just as
we have gentoo-sources vs gentoo-kernel).
In the same way, Eli and I have some different opinions on splitpkgs --
he's sort of convinced me that there's some utility in them, but they're
in no way *as useful* as they are on primarily-binary distributions.
But I don't consider myself an expert on kernel modules either, just the
fact that Ionen shares my unease (or I share his) makes me feel like
mine isn't unwarranted.
[...]
thanks,
sam
