Re: queue/5.15 kernel build failure

[Greg KH <gregkh@linuxfoundation.org>]

On Sun, Aug 17, 2025 at 04:05:18PM -0400, Chuck Lever wrote:
> On 8/17/25 4:02 PM, Sasha Levin wrote:
> > On Sun, Aug 17, 2025 at 01:11:14PM -0400, Chuck Lever wrote:
> >> Hi-
> >>
> >> Building on RHEL 9.6, I encountered this build failure:
> >>
> >> arch/x86/kernel/smp.o: warning: objtool: fred_sysvec_reboot()+0x52:
> >> unreachable instruction
> >> drivers/gpu/drm/vmwgfx/vmwgfx_msg.o: warning: objtool:
> >> vmw_port_hb_out()+0xbf: stack state mismatch: cfa1=5+16 cfa2=4+8
> >> drivers/gpu/drm/vmwgfx/vmwgfx_msg.o: warning: objtool:
> >> vmw_port_hb_in()+0xb4: stack state mismatch: cfa1=5+16 cfa2=4+8
> >> drivers/vfio/vfio_iommu_type1.c: In function ‘vfio_pin_pages_remote’:
> >> drivers/vfio/vfio_iommu_type1.c:707:25: error: ISO C90 forbids mixed
> >> declarations and code [-Werror=declaration-after-statement]
> >>  707 |                         long req_pages = min_t(long, npage,
> >> batch->capacity);
> >>      |                         ^~~~
> >> cc1: all warnings being treated as errors
> >> gmake[2]: *** [scripts/Makefile.build:289:
> >> drivers/vfio/vfio_iommu_type1.o] Error 1
> >> gmake[1]: *** [scripts/Makefile.build:552: drivers/vfio] Error 2
> >> gmake[1]: *** Waiting for unfinished jobs....
> >> gmake: *** [Makefile:1926: drivers] Error 2
> >>
> >> Appears to be due to:
> >>
> >> commit 5c87f3aff907e72fa6759c9dc66eb609dec1815c
> > 
> > I've dropped this, thanks for the report.
> > 
> > It's a bit funny - my version of gcc treats it as a warning, and it
> > actually
> > gives me quite a few mote "mixed decrlataions" warnings in the 5.15
> > allmodconfig build.
> > 
> > Compilers are hard :)
> > 
> 
> Additional context: I copied the RHEL 9.6 /boot/config to do the build.
> I think Red Hat likes to keep the "treat warnings as errors" setting
> enabled in their builds.

It's a good warning to have, 'allmodconfig' enables it, and so my builds
show these as failures too, so you aren't alone.

thanks for pointing it out.

greg k-h