On Thu, Apr 06, 2023 at 10:30:22PM +0100, Jiaxun Yang wrote: > > > > 2023年4月6日 22:19,Jiaxun Yang <jiaxun.yang@xxxxxxxxxxx> 写道: > > > > > > > >> 2023年4月6日 22:09,Nathan Chancellor <nathan@xxxxxxxxxx> 写道: > >> > >> On Thu, Apr 06, 2023 at 09:59:45PM +0100, Jiaxun Yang wrote: > >>> > >>> > >>>> 2023年4月6日 21:09,Nathan Chancellor <nathan@xxxxxxxxxx> 写道: > >>>> > >>>> When building allnoconfig with clang after commit de34007751aa ("MIPS: > >>>> generic: Enable all CPUs supported by virt board in Kconfig"), the > >>>> following error occurs: > >>>> > >>>> error: unknown target CPU 'r4600' > >>>> note: valid target CPU values are: mips1, mips2, mips3, mips4, mips5, mips32, mips32r2, mips32r3, mips32r5, mips32r6, mips64, mips64r2, mips64r3, mips64r5, mips64r6, octeon, octeon+, p5600 > >>>> > >>>> Working around that, there are similar errors for 'loongson2e' and > >>>> 'loongson2f'. > >>>> > >>>> These CPUs are not supported in clang/LLVM, so do not select support for > >>>> them in MIPS_GENERIC_KERNEL when building with clang. > >>>> > >>>> Fixes: de34007751aa ("MIPS: generic: Enable all CPUs supported by virt board in Kconfig") > >>>> Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx> > >>> > >>> Thanks for the patch. > >>> > >>> Actually there is no need for any special support for those CPUs. > >>> We should be able to build those kernels with -march=mips3. > >>> > >>> I think something like: > >>> > >>> --- a/arch/mips/Makefile > >>> +++ b/arch/mips/Makefile > >>> @@ -150,7 +150,7 @@ cflags-y += $(call cc-option,-Wa$(comma)-mno-fix-loongson3-llsc,) > >>> # > >>> cflags-$(CONFIG_CPU_R3000) += -march=r3000 > >>> cflags-$(CONFIG_CPU_R4300) += -march=r4300 -Wa,--trap > >>> -cflags-$(CONFIG_CPU_R4X00) += -march=r4600 -Wa,--trap > >>> +cflags-$(CONFIG_CPU_R4X00) += $(call cc-option,-march=r4600,-march=mips3) -Wa,--trap > >>> cflags-$(CONFIG_CPU_TX49XX) += -march=r4600 -Wa,--trap > >>> cflags-$(CONFIG_CPU_MIPS32_R1) += -march=mips32 -Wa,--trap > >>> cflags-$(CONFIG_CPU_MIPS32_R2) += -march=mips32r2 -Wa,--trap > >>> @@ -181,8 +181,8 @@ endif > >>> cflags-$(CONFIG_CAVIUM_CN63XXP1) += -Wa,-mfix-cn63xxp1 > >>> cflags-$(CONFIG_CPU_BMIPS) += -march=mips32 -Wa,-mips32 -Wa,--trap > >>> > >>> -cflags-$(CONFIG_CPU_LOONGSON2E) += -march=loongson2e -Wa,--trap > >>> -cflags-$(CONFIG_CPU_LOONGSON2F) += -march=loongson2f -Wa,--trap > >>> +cflags-$(CONFIG_CPU_LOONGSON2E) += $(call cc-option,-march=loongson2e,-march=mips3) -Wa,--trap > >>> +cflags-$(CONFIG_CPU_LOONGSON2F) += $(call cc-option,-march=loongson2f,-march=mips3) -Wa,--trap > >>> # Some -march= flags enable MMI instructions, and GCC complains about that > >>> # support being enabled alongside -msoft-float. Thus explicitly disable MMI. > >>> cflags-$(CONFIG_CPU_LOONGSON2EF) += $(call cc-option,-mno-loongson-mmi) > >>> > >>> Will make them build. > >> > >> Thank you for taking a look and the suggestion! I applied it and tried > >> to build allnoconfig but I get > >> > >> error: ABI 'o32' is not supported on CPU 'mips3' > >> > >> immediately, which could certainly be a bug in clang... > > > > There is a clang patch: > > https://reviews.llvm.org/D146269 Aha, good to know that issue is finally getting resolved :) > > I’ve seen this warning with CONFIG_MIPS32_O32 enabled, but I think that’s not the case for allnoconfig... > > > Oh I see, it’s trying to build a o32 kernel. I can test this diff tomorrow. Sounds like you have a better grasp on this problem than I do though so it would probably be better if you sent the patch but I do not mind doing it if you are unable to. For the record, with allnoconfig I end up with: $ rg 64BIT .config 292:CONFIG_SYS_SUPPORTS_64BIT_KERNEL=y 294:CONFIG_CPU_SUPPORTS_64BIT_KERNEL=y 302:# CONFIG_64BIT is not set $ rg O32 .config 345:# CONFIG_MIPS_O32_FP64_SUPPORT is not set > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -1579,7 +1579,7 @@ config CPU_R4300 > config CPU_R4X00 > bool "R4x00" > depends on SYS_HAS_CPU_R4X00 > - select CPU_SUPPORTS_32BIT_KERNEL > + select CPU_SUPPORTS_32BIT_KERNEL if CC_SUPPORTS_O32_WITH_64BIT_ARCH > select CPU_SUPPORTS_64BIT_KERNEL > select CPU_SUPPORTS_HUGEPAGES > help > @@ -1743,9 +1743,11 @@ config CPU_MIPS32_R5_XPA > if CPU_LOONGSON2F > config CPU_NOP_WORKAROUNDS > bool > + depends on $(cc-option,-Wa,-mfix-loongson2f-nop) > config CPU_JUMP_WORKAROUNDS > bool > + depends on $(cc-option,-Wa,-mfix-loongson2f-jump) > config CPU_LOONGSON2F_WORKAROUNDS > bool "Loongson 2F Workarounds" > @@ -2497,6 +2499,7 @@ config CPU_HAS_SYNC > # "MIPS R4400MC Errata, Processor Revision 1.0", erratum #5 > config CPU_DADDI_WORKAROUNDS > bool > + depends on $(cc-option,-mno-daddi) > # Work around certain R4000 CPU errata (as implemented by GCC): > # > @@ -2518,6 +2521,7 @@ config CPU_DADDI_WORKAROUNDS > # erratum #52 > config CPU_R4000_WORKAROUNDS > bool > + depends on $(cc-option,-mfix-r4000) > select CPU_R4400_WORKAROUNDS > # Work around certain R4400 CPU errata (as implemented by GCC): > @@ -2528,6 +2532,7 @@ config CPU_R4000_WORKAROUNDS > # "MIPS R4400MC Errata, Processor Revision 2.0 & 3.0", erratum #4 > config CPU_R4400_WORKAROUNDS > bool > + depends on $(cc-option,-mfix-r4400) > config CPU_R4X00_BUGS64 > bool > @@ -3174,6 +3179,7 @@ config COMPAT > config MIPS32_O32 > bool "Kernel support for o32 binaries" > depends on 64BIT > + depends on CC_SUPPORTS_O32_WITH_64BIT_ARCH > select ARCH_WANT_OLD_COMPAT_IPC > select COMPAT > select MIPS32_COMPAT > @@ -3206,6 +3212,9 @@ config CC_HAS_MNO_BRANCH_LIKELY > config CC_HAS_BROKEN_INLINE_COMPAT_BRANCH > def_bool y if CC_IS_CLANG > +config CC_SUPPORTS_O32_WITH_64BIT_ARCH > + def_bool y if $(cc-option,-march=mips3 -mabi=o32) > + > menu "Power management options" > config ARCH_HIBERNATION_POSSIBLE > > This will prevent clang build 32bit kernel in case it doesn’t support o32 ABI with 64bit CPU. Cheers, Nathan