Re: [PATCH net-next v2 2/2] selftests: drv-net: Use cross-compilation environment for the io_uring check

[Matthieu Baerts <matttbe@kernel.org>]

On 07/09/2026 15:51, Maxime Chevallier wrote:
> Hi,
> 
> On 9/6/26 17:00, netdev-bot+sashiko@kernel.org wrote:
>> Thank you for your contribution! Sashiko AI review found 2 potential
>> issue(s) to consider:
>>
>> Critical: 0 · High: 0 · Medium: 1 · Low: 1
>>
>> - [Medium] Incomplete fix: the capability probe still uses a different
>>   compiler than the one lib.mk installs to build `iou-zcrx`, in two…
>> - [Low] Missing `Fixes:` tag.
>>
>> --
>>
>> selftests: drv-net: Use cross-compilation environment for the io_uring check
>>
>> This patch sets CC to $(CROSS_COMPILE)gcc at the top of
>> tools/testing/selftests/drivers/net/hw/Makefile so that the liburing
>> zero-copy capability probe (HAS_IOURING_ZCRX) is compiled with the
>> cross compiler instead of make's built-in default. The override is
>> guarded by ifeq ($(LLVM)$(CC),cc).
>>
>> [Severity: Low]
>>
>> Should this carry a Fixes: tag?  git blame on the baseline attributes the
>> whole probe block, including the ifeq ($(HAS_IOURING_ZCRX),y) gating, to
>> f81171fecd0c3 ("selftests: hw-net: auto-disable building the iouring C
>> code").  Since no CC is set before the probe in this Makefile, in
>> tools/testing/selftests/Makefile, or in lib.mk, that commit is where the
>> probe started evaluating with the built-in CC=cc in cross builds:
>>
>>   Fixes: f81171fecd0c3 ("selftests: hw-net: auto-disable building the iouring C code")
> 
> Yeah but OTHO this never worked, and apparently was never tested before.
> 
>>
>> On the changelog wording:
>>
>>> The CC value used for the io_uring library check defaults to the host
>>> compiler, which will fail in cross-compiling environments.
> 
> I'll reword yeah...
> 
> [...]
> 
>>
>> Since the probe is expanded well before include ../../../lib.mk, would it
>> be possible to mirror lib.mk's own CC derivation here, or to move the probe
>> after lib.mk is included, so the gate always matches the compiler that
>> builds iou-zcrx?
> 
> Well this is what I wanted to avoid :(
> 
> Let me reword the commit log for V2, Matthieu if that's OK I'll also keep your
> R-b, as I'll leave the code as-is unless someone has any objection ?

Fine by me to document this "limitation" but keep it as is: I think the
proposed "workaround" is enough for this case.

Cheers,
Matt