* Re: [PATCH 2/2] powerpc/64: Use -mtune=pwr10/9/8 for clang [not found] ` <20230302131656.50626-2-mpe@ellerman.id.au> @ 2023-03-02 16:43 ` Nathan Chancellor 2023-03-02 23:53 ` Michael Ellerman 0 siblings, 1 reply; 3+ messages in thread From: Nathan Chancellor @ 2023-03-02 16:43 UTC (permalink / raw) To: Michael Ellerman; +Cc: linuxppc-dev, linux-kbuild, llvm, Nick Desaulniers Hi Michael, Thanks for the workaround and sorry this has come to bite us :/ On Fri, Mar 03, 2023 at 12:16:56AM +1100, Michael Ellerman wrote: > For the -mtune option clang doesn't accept power10/9/8, instead it > accepts pwr10/9/8. That will be fixed in future versions of clang, but > the kernel must support the clang versions in the wild. > > So add support for the "pwr" spelling if clang is in use. > > Reported-by: Nathan Chancellor <nathan@kernel.org> I think that should actually be Reported-by: Nick Desaulniers <ndesaulniers@google.com> > BugLink: https://github.com/ClangBuiltLinux/linux/issues/1799 > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Reviewed-by: Nathan Chancellor <nathan@kernel.org> > --- > arch/powerpc/platforms/Kconfig.cputype | 4 ++++ > 1 file changed, 4 insertions(+) > > Need to confirm the clang <= 16 statement is correct. Currently, this is indeed the case. It is possible that Nemanja's patch will get applied to release/16.x before 16.0.0 final but it might not. We can always update it later. I think we do want to push to get that patch applied because I forgot that it is only in 16.0.0 that '-mtune' starts to do something on PowerPC: https://github.com/llvm/llvm-project/commit/1dc26b80b872a94c581549a21943756a8c3448a3 Prior to that change, '-mtune' was accepted but did nothing. It is only once it was hooked up to the backend that we got the spew of warnings. I think that warrants us trying to get Nemanja's patch into 16.0.0, which may allow us to drop this workaround altogether... > diff --git a/arch/powerpc/platforms/Kconfig.cputype b/arch/powerpc/platforms/Kconfig.cputype > index 7d7477b73951..e4e0e81be7de 100644 > --- a/arch/powerpc/platforms/Kconfig.cputype > +++ b/arch/powerpc/platforms/Kconfig.cputype > @@ -278,6 +278,10 @@ config TUNE_CPU > default "-mtune=power10" if POWERPC64_CPU && CC_IS_GCC && $(cc-option,-mtune=power10) > default "-mtune=power9" if POWERPC64_CPU && CC_IS_GCC && $(cc-option,-mtune=power9) > default "-mtune=power8" if POWERPC64_CPU && CC_IS_GCC && $(cc-option,-mtune=power8) > + # clang <= 16 only supports the "pwr" names > + default "-mtune=pwr10" if POWERPC64_CPU && CC_IS_CLANG && $(cc-option,-mtune=pwr10) > + default "-mtune=pwr9" if POWERPC64_CPU && CC_IS_CLANG && $(cc-option,-mtune=pwr9) > + default "-mtune=pwr8" if POWERPC64_CPU && CC_IS_CLANG && $(cc-option,-mtune=pwr8) > > config PPC_BOOK3S > def_bool y > -- > 2.39.2 > ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] powerpc/64: Use -mtune=pwr10/9/8 for clang 2023-03-02 16:43 ` [PATCH 2/2] powerpc/64: Use -mtune=pwr10/9/8 for clang Nathan Chancellor @ 2023-03-02 23:53 ` Michael Ellerman 2023-03-03 15:14 ` Nathan Chancellor 0 siblings, 1 reply; 3+ messages in thread From: Michael Ellerman @ 2023-03-02 23:53 UTC (permalink / raw) To: Nathan Chancellor; +Cc: linuxppc-dev, linux-kbuild, llvm, Nick Desaulniers Nathan Chancellor <nathan@kernel.org> writes: > Hi Michael, > > Thanks for the workaround and sorry this has come to bite us :/ > > On Fri, Mar 03, 2023 at 12:16:56AM +1100, Michael Ellerman wrote: >> For the -mtune option clang doesn't accept power10/9/8, instead it >> accepts pwr10/9/8. That will be fixed in future versions of clang, but >> the kernel must support the clang versions in the wild. >> >> So add support for the "pwr" spelling if clang is in use. >> >> Reported-by: Nathan Chancellor <nathan@kernel.org> > > I think that should actually be > > Reported-by: Nick Desaulniers <ndesaulniers@google.com> I guess yeah. >> BugLink: https://github.com/ClangBuiltLinux/linux/issues/1799 >> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> > > Reviewed-by: Nathan Chancellor <nathan@kernel.org> Thanks. >> --- >> arch/powerpc/platforms/Kconfig.cputype | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> Need to confirm the clang <= 16 statement is correct. > > Currently, this is indeed the case. It is possible that Nemanja's patch > will get applied to release/16.x before 16.0.0 final but it might not. > > We can always update it later. I think we do want to push to get that > patch applied because I forgot that it is only in 16.0.0 that '-mtune' > starts to do something on PowerPC: > > https://github.com/llvm/llvm-project/commit/1dc26b80b872a94c581549a21943756a8c3448a3 > > Prior to that change, '-mtune' was accepted but did nothing. It is only > once it was hooked up to the backend that we got the spew of warnings. I > think that warrants us trying to get Nemanja's patch into 16.0.0, which > may allow us to drop this workaround altogether... Aha OK, I missed that the warning was new in 16. I'll sit on this for now then until we know if that change will make it into clang 16. cheers ^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 2/2] powerpc/64: Use -mtune=pwr10/9/8 for clang 2023-03-02 23:53 ` Michael Ellerman @ 2023-03-03 15:14 ` Nathan Chancellor 0 siblings, 0 replies; 3+ messages in thread From: Nathan Chancellor @ 2023-03-03 15:14 UTC (permalink / raw) To: Michael Ellerman; +Cc: linuxppc-dev, linux-kbuild, llvm, Nick Desaulniers On Fri, Mar 03, 2023 at 10:53:02AM +1100, Michael Ellerman wrote: > Nathan Chancellor <nathan@kernel.org> writes: > > Hi Michael, > > > > Thanks for the workaround and sorry this has come to bite us :/ > > > > On Fri, Mar 03, 2023 at 12:16:56AM +1100, Michael Ellerman wrote: > >> For the -mtune option clang doesn't accept power10/9/8, instead it > >> accepts pwr10/9/8. That will be fixed in future versions of clang, but > >> the kernel must support the clang versions in the wild. > >> > >> So add support for the "pwr" spelling if clang is in use. > >> > >> Reported-by: Nathan Chancellor <nathan@kernel.org> > > > > I think that should actually be > > > > Reported-by: Nick Desaulniers <ndesaulniers@google.com> > > I guess yeah. > > >> BugLink: https://github.com/ClangBuiltLinux/linux/issues/1799 > >> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> > > > > Reviewed-by: Nathan Chancellor <nathan@kernel.org> > > Thanks. > > >> --- > >> arch/powerpc/platforms/Kconfig.cputype | 4 ++++ > >> 1 file changed, 4 insertions(+) > >> > >> Need to confirm the clang <= 16 statement is correct. > > > > Currently, this is indeed the case. It is possible that Nemanja's patch > > will get applied to release/16.x before 16.0.0 final but it might not. > > > > We can always update it later. I think we do want to push to get that > > patch applied because I forgot that it is only in 16.0.0 that '-mtune' > > starts to do something on PowerPC: > > > > https://github.com/llvm/llvm-project/commit/1dc26b80b872a94c581549a21943756a8c3448a3 > > > > Prior to that change, '-mtune' was accepted but did nothing. It is only > > once it was hooked up to the backend that we got the spew of warnings. I > > think that warrants us trying to get Nemanja's patch into 16.0.0, which > > may allow us to drop this workaround altogether... > > Aha OK, I missed that the warning was new in 16. > > I'll sit on this for now then until we know if that change will make it > into clang 16. It was merged into release/16.x a few hours ago: https://github.com/llvm/llvm-project/issues/61128 https://github.com/llvm/llvm-project/commit/9b2e09e9fb1aa3bbe3668d7cc585188a3014d1b9 So I think this particular workaround is no longer needed :) Cheers, Nathan ^ permalink raw reply [flat|nested] 3+ messages in thread
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2023-03-02 16:43 ` [PATCH 2/2] powerpc/64: Use -mtune=pwr10/9/8 for clang Nathan Chancellor
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