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From: Nathan Chancellor <nathan@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com,
	Nathan Chancellor <nathan@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>
Subject: [PATCH v2] arm64: Make CPU_BIG_ENDIAN depend on ld.bfd or ld.lld 13.0.0+
Date: Mon,  8 Feb 2021 17:57:20 -0700	[thread overview]
Message-ID: <20210209005719.803608-1-nathan@kernel.org> (raw)
In-Reply-To: <20210202022441.1451389-1-nathan@kernel.org>

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>
---

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_ENDIAN

base-commit: 92bf22614b21a2706f4993b278017e437f7785b3
-- 
2.30.1


  parent reply	other threads:[~2021-02-09  0:59 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-02  2:24 [PATCH] arm64: Make CPU_BIG_ENDIAN depend on !LD_IS_LLD Nathan Chancellor
2021-02-02  8:04 ` Arnd Bergmann
2021-02-02 19:51   ` Nathan Chancellor
2021-02-02 20:43     ` Arnd Bergmann
2021-02-03 10:08       ` Peter Smith
2021-02-07  2:30 ` Nathan Chancellor
2021-02-09  0:57 ` Nathan Chancellor [this message]
2021-02-09  1:39   ` [PATCH v2] arm64: Make CPU_BIG_ENDIAN depend on ld.bfd or ld.lld 13.0.0+ Nick Desaulniers
2021-02-09 14:35   ` Will Deacon

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