Re: Build regressions/improvements in v5.12-rc1

[Christophe Leroy]

Le 02/03/2021 à 21:01, Geert Uytterhoeven a écrit :
> Hi Alex,
>
> On Tue, Mar 2, 2021 at 8:30 PM Alex Deucher <alexdeucher@xxxxxxxxx> wrote:
> > On Mon, Mar 1, 2021 at 9:21 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> > > On Mon, 1 Mar 2021, Geert Uytterhoeven wrote:
> > > > Below is the list of build error/warning regressions/improvements in
> > > > v5.12-rc1[1] compared to v5.11[2].
> > > >
> > > > Summarized:
> > > >   - build errors: +2/-0
> > >
> > > > [1] http://kisskb.ellerman.id.au/kisskb/branch/linus/head/fe07bfda2fb9cdef8a4d4008a409bb02f35f1bd8/ (all 192 configs)
> > > > [2] http://kisskb.ellerman.id.au/kisskb/branch/linus/head/f40ddce88593482919761f74910f42f4b84c004b/ (all 192 configs)
> > > >
> > > >
> > > > *** ERRORS ***
> > > >
> > > > 2 error regressions:
> > > >   + /kisskb/src/drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c: error: implicit declaration of function 'disable_kernel_vsx' [-Werror=implicit-function-declaration]:  => 674:2
> > > >   + /kisskb/src/drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c: error: implicit declaration of function 'enable_kernel_vsx' [-Werror=implicit-function-declaration]:  => 638:2
> > >
> > > powerpc-gcc4.9/ppc64_book3e_allmodconfig
> > >
> > > This was fixed in v5.11-rc1, but reappeared in v5.12-rc1?
> >
> > Do you know what fixed in for 5.11?  I guess for PPC64 we depend on CONFIG_VSX?
>
> Looking at the kisskb build logs for v5.11*, it seems compilation never
> got to drivers/gpu/drm/ due to internal compiler errors that weren't caught
> by my scripts.  So the errors listed above were not really fixed.

As far as I can see, the problem has been there for any config without CONFIG_VSX from the beginning 
ie since https://github.com/linuxppc/linux/commit/16a9dea110a6

The following should fix it up:

diff --git a/arch/powerpc/include/asm/switch_to.h b/arch/powerpc/include/asm/switch_to.h
index fdab93428372..9d1fbd8be1c7 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -71,6 +71,16 @@ static inline void disable_kernel_vsx(void)
 {
 	msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX);
 }
+#else
+static inline void enable_kernel_vsx(void)
+{
+	BUILD_BUG();
+}
+
+static inline void disable_kernel_vsx(void)
+{
+	BUILD_BUG();
+}
 #endif

 #ifdef CONFIG_SPE
---
Christophe
Christophe