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Date: Wed, 10 Jan 2024 09:58:22 +1100
From: Stephen Rothwell <sfr@canb.auug.org.au>
To: "Paul E. McKenney" <paulmck@kernel.org>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>,
 linux-kernel@vger.kernel.org, intel-xe@lists.freedesktop.org
Subject: Re: [BUG] allmodconfig build error in next-20240108
Message-ID: <20240110095822.3ba3d979@canb.auug.org.au>
In-Reply-To: <d61dfe52-9567-4f62-98f5-5c1e00cb4708@paulmck-laptop>
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Hi all,

On Tue, 9 Jan 2024 14:45:56 -0800 "Paul E. McKenney" <paulmck@kernel.org> w=
rote:
>
> On Wed, Jan 10, 2024 at 08:11:55AM +1100, Stephen Rothwell wrote:
> >=20
> > On Tue, 9 Jan 2024 10:58:40 -0600 Lucas De Marchi <lucas.demarchi@intel=
com> wrote: =20
> > >
> > > On Mon, Jan 08, 2024 at 03:15:23PM -0800, Paul E. McKenney wrote: =20
> > > I could reproduce it with allmodconfig and gcc 11.4.1 from rockylinux,
> > > but not with gcc 9.3 or 12.3. Also it's not reproduced with gcc 11.4.1
> > > when using defconfig + CONFIG_DRM_XE  (even if  -Wstringop-overflow is
> > > still added).
> > >=20
> > > I don't see a bug in the code, even if it inverts the head/tail
> > > convention.
> > >=20
> > > Searching around showed this which may be relevant: https://gcc.gnu.o=
rg/bugzilla/show_bug.cgi?id=3D101854
> > > At least I can reproduce the same issue as in the snippet provided
> > > (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101854#c7) with the b=
uggy
> > > compiler.
> > >=20
> > > So, maybe the best thing to do for now is to disable -Wstringop-overf=
low
> > > for gcc < 12?
> > >=20
> > >=20
> > > ------8<-----
> > > diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> > > index 6952da8979ea..0433a3c6cbfd 100644
> > > --- a/drivers/gpu/drm/xe/Makefile
> > > +++ b/drivers/gpu/drm/xe/Makefile
> > > @@ -17,7 +17,7 @@ subdir-ccflags-y +=3D $(call cc-option, -Wunused-co=
nst-variable)
> > >   subdir-ccflags-y +=3D $(call cc-option, -Wpacked-not-aligned)
> > >   subdir-ccflags-y +=3D $(call cc-option, -Wformat-overflow)
> > >   subdir-ccflags-y +=3D $(call cc-option, -Wformat-truncation)
> > > -subdir-ccflags-y +=3D $(call cc-option, -Wstringop-overflow)
> > > +subdir-ccflags-$(call gcc-min-version, 120000) +=3D $(call cc-option=
, -Wstringop-overflow)
> > >   subdir-ccflags-y +=3D $(call cc-option, -Wstringop-truncation)
> > >   # The following turn off the warnings enabled by -Wextra
> > >   ifeq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
> > > ------8<----- =20
>=20
> This I did, thank you!

Maybe that line "subdir-ccflags-y +=3D $(call cc-option, -Wstringop-overflo=
w)"
should just be removed as the setting of that option has been moved to the
normal C flags in the top level Makefile (out of Makefile.extrawarn).

--=20
Cheers,
Stephen Rothwell

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