linux-kernel - Re: [PATCH] vfio: selftests: fix format conversion compiler warning

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Message-ID: <CALzav=cUDm6xSzw=KZeNmZT2=YKL+9N=_qLRmiCSvSBhbsAfew@mail.gmail.com>
Date: Thu, 29 Jan 2026 14:57:59 -0800
From: David Matlack <dmatlack@...gle.com>
To: Alex Williamson <alex@...zbot.org>
Cc: Randy Dunlap <rdunlap@...radead.org>, Ted Logan <tedlogan@...com>, 
	Shuah Khan <shuah@...nel.org>, Raghavendra Rao Ananta <rananta@...gle.com>, Alex Mastro <amastro@...com>, 
	kvm@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	linux-kernel@...r.kernel.org, kernel test robot <lkp@...el.com>
Subject: Re: [PATCH] vfio: selftests: fix format conversion compiler warning

On Thu, Jan 29, 2026 at 10:50 AM Alex Williamson <alex@...zbot.org> wrote:
>
> On Wed, 28 Jan 2026 11:21:52 -0800
> David Matlack <dmatlack@...gle.com> wrote:
>
> > On Wed, Jan 28, 2026 at 11:12 AM Randy Dunlap <rdunlap@...radead.org> wrote:
> > > On 1/28/26 11:06 AM, David Matlack wrote:
> > > > On Wed, Jan 28, 2026 at 10:38 AM Ted Logan <tedlogan@...com> wrote:
> > > >>
> > > >> Use the standard format conversion macro PRIx64 to generate the
> > > >> appropriate format conversion for 64-bit integers. Fixes a compiler
> > > >> warning with -Wformat on i386.
> > > >>
> > > >> Signed-off-by: Ted Logan <tedlogan@...com>
> > > >> Reported-by: kernel test robot <lkp@...el.com>
> > > >> Closes: https://lore.kernel.org/oe-kbuild-all/202601211830.aBEjmEFD-lkp@intel.com/
> > > >
> > > > Thanks for the patch.
> > > >
> > > > I've been seeing these i386 reports as well. I find the PRIx64, etc.
> > > > format specifiers make format strings very hard to read. And I think
> > > > there were some other issues when building VFIO selftests with i386
> > > > the last time I tried.
> > > >
> > > > I was thinking instead we should just not support i386 builds of VFIO
> > > > selftests. But I hadn't gotten around to figuring out the right
> > > > Makefile magic to make that happen.
> > >
> > > There are other 32-bit CPUs besides i386.
> > > Or do only support X86?
> >
> > At this point I would only call x86_64 and arm64 as supported. At
> > least that is all I have access to and tested.
> >
> > If there is legitimate desire to run these tests on 32-bit CPUs, then
> > we can support it.
> >
> > Alex, do you test on 32-bit CPUs?
>
> No, I haven't tested 32-bit in a very long time.  I'd like to think it
> works, but I'm not aware of any worthwhile use case.

Ok, thanks. Then let's defer making the selftests code 32-bit
compatible until there's a use-case / demand.

Ted, would you be able to send another to change to opt-out VFIO
selftests from 32-bit builds to avoid future kernel test robot
reports?