Re: [PATCH v2] arm64: Make CPU_BIG_ENDIAN depend on ld.bfd or ld.lld 13.0.0+
From: Nick Desaulniers <ndesaulniers@google.com>
Date: 2021-02-09 01:42:23
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On Mon, Feb 8, 2021 at 4:58 PM Nathan Chancellor [off-list ref] wrote:
Similar to commit 28187dc8ebd9 ("ARM: 9025/1: Kconfig: CPU_BIG_ENDIAN
depends on !LD_IS_LLD"), ld.lld prior to 13.0.0 does not properly
support aarch64 big endian, leading to the following build error when
CONFIG_CPU_BIG_ENDIAN is selected:
ld.lld: error: unknown emulation: aarch64linuxb
This has been resolved in LLVM 13. To avoid errors like this, only allow
CONFIG_CPU_BIG_ENDIAN to be selected if using ld.bfd or ld.lld 13.0.0
and newer.
While we are here, the indentation of this symbol used spaces since its
introduction in commit a872013d6d03 ("arm64: kconfig: allow
CPU_BIG_ENDIAN to be selected"). Change it to tabs to be consistent with
kernel coding style.
Link: https://github.com/ClangBuiltLinux/linux/issues/380
Link: https://github.com/ClangBuiltLinux/linux/issues/1288
Link: https://github.com/llvm/llvm-project/commit/7605a9a009b5fa3bdac07e3131c8d82f6d08feb7
Link: https://github.com/llvm/llvm-project/commit/eea34aae2e74e9b6fbdd5b95f479bc7f397bf387
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>LGTM, thanks for implementing BE support for aarch64 in LLD, Fangrui! (And Nathan for the kernel patch+testing) Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
quoted hunk ↗ jump to hunk
--- v1 -> v2: * Conditionally disable CONFIG_CPU_BIG_ENDIAN for older versions of ld.lld now that proper support has been added to ld.lld 13+ (thanks to the quick work of Fangrui Song). arch/arm64/Kconfig | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index f39568b28ec1..912da4e2ab59 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig@@ -952,8 +952,9 @@ choice that is selected here. config CPU_BIG_ENDIAN - bool "Build big-endian kernel" - help + bool "Build big-endian kernel" + depends on !LD_IS_LLD || LLD_VERSION >= 130000 + help Say Y if you plan on running a kernel with a big-endian userspace. config CPU_LITTLE_ENDIANbase-commit: 92bf22614b21a2706f4993b278017e437f7785b3 -- 2.30.1
-- Thanks, ~Nick Desaulniers _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel