Message ID | 20181011024303.23921-1-joel@jms.id.au (mailing list archive) |
---|---|
State | Accepted |
Commit | 960e30029863db95ec79a71009272d4661db5991 |
Headers | show |
Series | [v3] powerpc/Makefile: Fix PPC_BOOK3S_64 ASFLAGS | expand |
Context | Check | Description |
---|---|---|
snowpatch_ozlabs/apply_patch | success | next/apply_patch Successfully applied |
snowpatch_ozlabs/checkpatch | success | Test checkpatch on branch next |
snowpatch_ozlabs/build-ppc64le | success | Test build-ppc64le on branch next |
snowpatch_ozlabs/build-ppc64be | success | Test build-ppc64be on branch next |
snowpatch_ozlabs/build-ppc64e | success | Test build-ppc64e on branch next |
snowpatch_ozlabs/build-ppc32 | success | Test build-ppc32 on branch next |
Joel Stanley <joel@jms.id.au> writes: > Ever since commit 15a3204d24a3 ("powerpc/64s: Set assembler machine type > to POWER4") we force -mpower4 to be passed to the assembler irrespective > of the CFLAGS used. ... > > By explicitly setting -many we can build with Clang and GCC while > retaining the -mpower4 option. > > Signed-off-by: Joel Stanley <joel@jms.id.au> > --- > Following up on: > https://lore.kernel.org/linuxppc-dev/20180914040649.1794-2-joel@jms.id.au/ > https://lore.kernel.org/linuxppc-dev/20180821010203.23213-1-anton@ozlabs.org/ > > mpe, please trim the commit message if you think it's a bit verbose I thought it was bit short :P > We could test for these flags in case -many is removed in the future, > but if an assembler does not support -many then -mpower4 will probably > break it anyway. Yeah that's OK, breaking hypothetical future toolchains is fine. cheers
On Thu, 2018-10-11 at 02:43:03 UTC, Joel Stanley wrote: > Ever since commit 15a3204d24a3 ("powerpc/64s: Set assembler machine type > to POWER4") we force -mpower4 to be passed to the assembler irrespective > of the CFLAGS used. > > When building a powerpc64 kernel with clang, clang will not add -many to > the assembler flags, so any instructions that the compiler has generated > that are not available on power4 will cause an error: > > /usr/bin/as -a64 -mppc64 -mlittle-endian -mpower8 \ > -I ./arch/powerpc/include -I ./arch/powerpc/include/generated \ > -I ./include -I ./arch/powerpc/include/uapi \ > -I ./arch/powerpc/include/generated/uapi -I ./include/uapi \ > -I ./include/generated/uapi -I arch/powerpc -I arch/powerpc \ > -maltivec -mpower4 -o init/do_mounts.o /tmp/do_mounts-3b0a3d.s > /tmp/do_mounts-51ce54.s:748: Error: unrecognized opcode: `isel' > > GCC does include -many, so the GCC driven gas call will succeed: > > as -v -I ./arch/powerpc/include -I ./arch/powerpc/include/generated -I > ./include -I ./arch/powerpc/include/uapi > -I ./arch/powerpc/include/generated/uapi -I ./include/uapi > -I ./include/generated/uapi -I arch/powerpc -I arch/powerpc > -a64 -mpower8 -many -mlittle -maltivec -mpower4 -o init/do_mounts.o > > Note that isel is power7 and above for IBM CPUs. GCC only generates it > for Power9 and above, but the above test was run against the clang > generated assembly. > > Peter Bergner explains: > > > When using -many -mpower4, gas will first try and find a matching > > power4 mnemonic and failing that, it will then allow any valid mnemonic > > that gas knows about. GCC's use of -many predates me though. > > > > IIRC, Alan looked at trying to remove it, but I forget why he didn't. > > Could be either a gcc or gas issue at the time. I'm not sure whether > > issue still exists or not. He and I have modified how gas works > > internally a fair amount since he tried removing gcc use of -many > > > > I will also note that when using -many, gas will choose the first > > mnemonic that matches in the mnemonic table and we have (mostly) sorted > > the table so that server mnemonics show up earlier in the table than > > other mnemonics, so they'll be seen/chosen first > > By explicitly setting -many we can build with Clang and GCC while > retaining the -mpower4 option. > > Signed-off-by: Joel Stanley <joel@jms.id.au> Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/960e30029863db95ec79a71009272d cheers
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index 81552c7b46eb..ae097fa9abe9 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -249,7 +249,10 @@ cpu-as-$(CONFIG_4xx) += -Wa,-m405 cpu-as-$(CONFIG_ALTIVEC) += $(call as-option,-Wa$(comma)-maltivec) cpu-as-$(CONFIG_E200) += -Wa,-me200 cpu-as-$(CONFIG_E500) += -Wa,-me500 -cpu-as-$(CONFIG_PPC_BOOK3S_64) += -Wa,-mpower4 +# When using -many -mpower4 gas will first try and find a matching power4 +# mnemonic and failing that it will allow any valid mnemonic that GAS knows +# about. GCC will pass -many to GAS when assembling, clang does not +cpu-as-$(CONFIG_PPC_BOOK3S_64) += -Wa,-mpower4 -Wa,-many cpu-as-$(CONFIG_PPC_E500MC) += $(call as-option,-Wa$(comma)-me500mc) KBUILD_AFLAGS += $(cpu-as-y)