Re: [PATCH] MIPS: Add comment about CONFIG_MIPS32_O32 in loongson3_defconfig when build with Clang
From: Nathan Chancellor <nathan@kernel.org>
Date: 2021-03-04 02:04:12
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lkml
Subsystem:
mips, the rest · Maintainers:
Thomas Bogendoerfer, Linus Torvalds
On Thu, Mar 04, 2021 at 09:15:44AM +0800, Tiezhu Yang wrote:
quoted hunk ↗ jump to hunk
When build kernel with Clang [1]: $ make CC=clang loongson3_defconfig $ make CC=clang there exists the following error: Checking missing-syscalls for O32 CALL scripts/checksyscalls.sh error: ABI 'o32' is not supported on CPU 'mips64r2' make[1]: *** [Kbuild:48: missing-syscalls] Error 1 make: *** [arch/mips/Makefile:419: archprepare] Error 2 This is a known bug [2] with Clang, as Simon Atanasyan said, "There is no plan on support O32 for MIPS64 due to lack of resources". It is not a good idea to remove this config due to GCC works well, so add comment to point out this bug and suggest the users to remove CONFIG_MIPS32_O32=y in defconfig when build kernel with Clang. [1] https://www.kernel.org/doc/html/latest/kbuild/llvm.html [2] https://bugs.llvm.org/show_bug.cgi?id=38063 Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> --- arch/mips/configs/loongson3_defconfig | 3 +++ 1 file changed, 3 insertions(+)diff --git a/arch/mips/configs/loongson3_defconfig b/arch/mips/configs/loongson3_defconfig index 0e79f81..cacf9dd 100644 --- a/arch/mips/configs/loongson3_defconfig +++ b/arch/mips/configs/loongson3_defconfig@@ -35,6 +35,9 @@ CONFIG_NUMA=y CONFIG_SMP=y CONFIG_HZ_256=y CONFIG_KEXEC=y +# Please remove CONFIG_MIPS32_O32=y when build with Clang +# due to "ABI 'o32' is not supported on CPU 'mips64r2'", +# https://bugs.llvm.org/show_bug.cgi?id=38063 CONFIG_MIPS32_O32=y CONFIG_MIPS32_N32=y CONFIG_VIRTUALIZATION=y-- 2.1.0
I think this might be a better solution. I know that I personally never read defconfig files if a build fails. If CONFIG_MIPS32_O32 is broken with clang and the MIPS backend maintainer has said that it will not be supported due to lack of resources, then the config should not even be selectable in my opinion. Cheers, Nathan
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index d89efba3d8a4..ed35318a759d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig@@ -3315,6 +3315,8 @@ config SYSVIPC_COMPAT config MIPS32_O32 bool "Kernel support for o32 binaries" depends on 64BIT + # https://bugs.llvm.org/show_bug.cgi?id=38063 + depends on $(success,$(CC) $(CLANG_FLAGS) -march=mips64 -o32 -c -x c /dev/null -o /dev/null) select ARCH_WANT_OLD_COMPAT_IPC select COMPAT select MIPS32_COMPAT