Re: [PATCH] x86/mce: Fix build warning after MSR-interface switch

Jürgen Groß <[email protected]> Fri, 17 Jul 2026 13:03:45 +0200

Newsgroups	org.kernel.vger.linux-edac,org.kernel.vger.linux-kernel
Message-ID	<[email protected]>

On 17.07.26 12:25, Ingo Molnar wrote:
> 
> * Jürgen Groß <[email protected]> wrote:
> 
>> On 17.07.26 11:28, Ingo Molnar wrote:
>>>
>>> * Juergen Gross <[email protected]> wrote:
>>>
>>>> The recent switch to 64-bit MSR interfaces introduced a build warning.
>>>>
>>>> Fix it.
>>>>
>>>> Fixes: cff219368bd0 ("x86/mce: Stop using 32-bit MSR interfaces")
>>>> Reported-by: kernel test robot <[email protected]>
>>>> Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/
>>>> Signed-off-by: Juergen Gross <[email protected]>
>>>> ---
>>>> Said patch is in tip only right now, so this patch could either be added
>>>> on top or be folded into the original patch.
>>>> ---
>>>>    arch/x86/kernel/cpu/mce/p5.c | 2 +-
>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/x86/kernel/cpu/mce/p5.c b/arch/x86/kernel/cpu/mce/p5.c
>>>> index eb99f384d747..3c2b6cc918b1 100644
>>>> --- a/arch/x86/kernel/cpu/mce/p5.c
>>>> +++ b/arch/x86/kernel/cpu/mce/p5.c
>>>> @@ -44,7 +44,7 @@ noinstr void pentium_machine_check(struct pt_regs *regs)
>>>>    /* Set up machine check reporting for processors with Intel style MCE: */
>>>>    void intel_p5_mcheck_init(struct cpuinfo_x86 *c)
>>>>    {
>>>> -	u64 q;
>>>> +	u64 __maybe_unused q;
>>>
>>> Could we just fix the API to always assign 'q', instead of this
>>> ugly & vague annotation?
>>
>> q is always assigned. I believe the problem is that it is never read.
> 
> Indeed.
> 
>> OTOH this problem can be fixed easily after patch 31 of this series. I can send
>> a V2 of patch 32 to just drop the assignment to q. This will be possible as
>> rdmsrq() will be a function then, and not a macro requiring a variable being
>> passed as parameter.
> 
> That's fine with me, as long as the build failure is only for this
> i386 randconfig. If a new warning is generated for any of the
> more prominent configs we'll have to make it go away for
> the interim tree. (Because it's still not 100% clear whether
> we'll be able to do patch 31 in this cycle.)

You have my patch for that case. :-)


Juergen

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