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From:   Tiezhu Yang <yangtiezhu@loongson.cn>
To:     Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>
Cc:     linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com,
        Xuefeng Li <lixuefeng@loongson.cn>
Subject: [PATCH v2] MIPS: Make MIPS32_O32 depends on !CC_IS_CLANG
Date:   Thu,  4 Mar 2021 14:19:38 +0800
Message-Id: <1614838778-3696-1-git-send-email-yangtiezhu@loongson.cn>
Precedence: bulk

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 CONFIG_MIPS32_O32=y directly
in defconfig due to GCC works well, as Nathan said, the config
should not even be selectable when build kernel with Clang, so
just make MIPS32_O32 depends on !CC_IS_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/Kconfig | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 3a38d27..f6ba59f 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -3318,6 +3318,8 @@ 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 !CC_IS_CLANG
 	select ARCH_WANT_OLD_COMPAT_IPC
 	select COMPAT
 	select MIPS32_COMPAT
-- 
2.1.0