Re: [Buildroot] [PATCH 1/1] package/kmod: fix build with musl

[Fiona Klute via buildroot <buildroot@buildroot.org>]

Hi Thomas!

Am 09.05.24 um 22:51 schrieb Thomas Petazzoni:
> Hello Fiona,
>
> On Fri, 26 Apr 2024 23:51:44 +0200
> Fiona Klute via buildroot <buildroot@buildroot.org> wrote:
>
>> From: Fiona Klute <fiona.klute+wiwa@gmx.de>
>>
>> Patch from upstream PR still being discussed:
>> https://github.com/kmod-project/kmod/pull/32
>>
>> Signed-off-by: Fiona Klute <fiona.klute+wiwa@gmx.de>
>
> Thanks for the patch. One thing that I find strange is that I cannot
> reproduce. Yes, I get warnings due to basename(), but not an actual
> build failure (I'm using a toolchain based on musl 1.2.5). There are
> also no build failures in our autobuilders.
>
> Here is the defconfig that I tested:
>
> BR2_arm=y
> BR2_cortex_a9=y
> BR2_ARM_ENABLE_VFP=y
> BR2_TOOLCHAIN_EXTERNAL=y
> BR2_TOOLCHAIN_EXTERNAL_BOOTLIN=y
> BR2_TOOLCHAIN_EXTERNAL_BOOTLIN_ARMV7_EABIHF_MUSL_STABLE=y
> BR2_INIT_NONE=y
> BR2_SYSTEM_BIN_SH_NONE=y
> # BR2_PACKAGE_BUSYBOX is not set
> BR2_PACKAGE_KMOD=y
> BR2_PACKAGE_KMOD_TOOLS=y
> # BR2_TARGET_ROOTFS_TAR is not set
>
> I just get:
>
> tools/kmod.c: In function ‘kmod_help’:
> tools/kmod.c:71:40: warning: implicit declaration of function ‘basename’ [-Wimplicit-function-declaration]
>     71 |                         "Commands:\n", basename(argv[0]));
>        |                                        ^~~~~~~~
> tools/kmod.c:71:40: warning: nested extern declaration of ‘basename’ [-Wnested-externs]
> tools/kmod.c:65:16: warning: format ‘%s’ expects argument of type ‘char *’, but argument 2 has type ‘int’ [-Wformat=]
>     65 |         printf("kmod - Manage kernel modules: list, load, unload, etc\n"
>        |                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ......
>     71 |                         "Commands:\n", basename(argv[0]));
>        |                                        ~~~~~~~~~~~~~~~~~
>        |                                        |
>        |                                        int
>
>
> Thoughts?

That's exactly what I'm seeing too. The problem is that when you then
try to use the resulting binaries (e.g. modprobe) they segfault, because
what's expected to be a pointer is some other value (probably int, with
different length) and the result is an invalid pointer.

So the build passes, but the resulting kmod tools are unusable. That's
how I found the issue, I was wondering why no modules were loaded on my
board. I would've just switched to the Busybox equivalents, but they
can't handle compressed modules.

Sorry I wasn't clearer, I tried to keep the commit message short,
evidently too short.

Best regards,
Fiona

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