Re: [Buildroot] [PATCH 4/5] package/kmod: switch to Meson build

From: "Yann E. MORIN via buildroot" <buildroot@buildroot.org>
To: Marcus Hoffmann <buildroot@bubu1.eu>
Cc: Fiona Klute <fiona.klute@gmx.de>,
	buildroot@buildroot.org,
	Eric Le Bihan <eric.le.bihan.dev@free.fr>,
	Julien Olivain <ju.o@free.fr>
Subject: Re: [Buildroot] [PATCH 4/5] package/kmod: switch to Meson build
Date: Fri, 1 May 2026 09:29:23 +0200	[thread overview]
Message-ID: <afRWU1jyiPy6AMtO@landeda> (raw)
In-Reply-To: <aa4a5ba1-eb8c-46e1-8aba-572b1cf23835@bubu1.eu>

Marcus, Fiona, All,

On 2026-05-01 00:22 +0200, Marcus Hoffmann spake thusly:
[--SNIP--]
> > > Is the bindir/sbindir logic still required actually?
[--SNIP--]
> Yann, maybe you have some input here?
[--SNIP--]
> In general, this is a bit hard to grasp from just reviewing the .mk file
> without building different variations of this, so uhm, what symlnks are we
> trying to create from where to where and why?

The reason why we care about all this mess, is that busybox does
install its tools (lsmod, insmod et al.) if they do not already exist
(the 'install-noclobber' install rule in busybox), so we have to have
those exist in the place busybox would otherwise install its owns.

Otherwise, we'd end up with, e.g.:

    /bin/busybox
    /usr/bin/kmod       <- the real stuff
    /usr/bin/lsmod      <- symlink to busybox
    /usr/sbin/lsmod     <- symlink to kmod

And then, depending on PATH, one may not get the lsmod one expects.
Hence all this dance with the symlinks...

Tis was introduced in 78f5ac2908b3 (kmod: add option to install module
utilities), at a time when individual packages would depend on busybox
to ensure they would "win over busybox", but the comment about the above
was removed in 273f23a45252 (package/busybox: invert dependency with
kmod) when we switched the dependency over, to avoid having packages
replace files from a previously package (in the hope to have a clean
PPD build).

I agree that the handlng is not optimal, but mostly we're comment
explaining the reason for this dance is missing.

> > Whether that makes sense with the kmod binary in /usr/bin is a different
> > question: If /usr is on a separate partition (the ancient reason for the
> > split), the symlinks will be broken until that is mounted. I simply kept
> > the same behavior as before. If placing the symlinks in /usr/sbin in
> > builds with BR2_ROOTFS_MERGED_USR=n is fine, we can remove this whole
> > mess of conditionals. :-)

Check where busybox installs its own symlinks/hardlinks/scripts before
you drop the symlink dance.

As for /usr on a separate partition, I think this is completely ruled
out for the merged-usr case anyway. With unmerged-usr, I am not sure
Buildroot ever officially supported this anyway: as you point out, the
kmod binary is in usr, so usr-on-a-separate-partition-with-kmod never
worked since at least 2012, when 78f5ac2908b3 was introduced...

Regards,
Yann E. MORIN.

-- 
.-----------------.--------------------.------------------.--------------------.
|  Yann E. MORIN  | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software  Designer | \ / CAMPAIGN     |  ___               |
| +33 561 099 427 `------------.-------:  X  AGAINST      |  \e/  There is no  |
| http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL    |   v   conspiracy.  |
'------------------------------^-------^------------------^--------------------'
_______________________________________________
buildroot mailing list
buildroot@buildroot.org
https://lists.buildroot.org/mailman/listinfo/buildroot