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Date: Wed, 28 Nov 2018 11:07:47 -0500
From: Sasha Levin <sashal@kernel.org>
To: ndesaulniers@google.com
Cc: gregkh@linuxfoundation.org, stable@vger.kernel.org,
        Greg Hackmann <ghackmann@android.com>,
        Will Deacon <will.deacon@arm.com>,
        Greg Hackmann <ghackmann@google.com>,
        Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH] arm64: remove no-op -p linker flag
Message-ID: <20181128160747.GM131942@sasha-vm>
References: <20181127191520.17598-1-ndesaulniers@google.com>
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On Tue, Nov 27, 2018 at 11:15:20AM -0800, ndesaulniers@google.com wrote:
>From: Greg Hackmann <ghackmann@android.com>
>
>(commit 1a381d4a0a9a0f999a13faaba22bf6b3fc80dcb9 upstream)
>
>Linking the ARM64 defconfig kernel with LLVM lld fails with the error:
>
>  ld.lld: error: unknown argument: -p
>  Makefile:1015: recipe for target 'vmlinux' failed
>
>Without this flag, the ARM64 defconfig kernel successfully links with
>lld and boots on Dragonboard 410c.
>
>After digging through binutils source and changelogs, it turns out that
>-p is only relevant to ancient binutils installations targeting 32-bit
>ARM.  binutils accepts -p for AArch64 too, but it's always been
>undocumented and silently ignored.  A comment in
>ld/emultempl/aarch64elf.em explains that it's "Only here for backwards
>compatibility".
>
>Since this flag is a no-op on ARM64, we can safely drop it.
>
>Acked-by: Will Deacon <will.deacon@arm.com>
>Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
>Signed-off-by: Greg Hackmann <ghackmann@google.com>
>Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
>Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
>---
>This is needed for linking arm64 kernels with LLVM's LLD linker.  I'm
>most interested in this for 4.14 and know it applies cleanly there, but
>would like it in 4.9 and 4.4 if possible. The upstream patch first
>landed in v4.18-rc4.

I've queued it for 4.14, 4.9, 4.4 and 3.18.

--
Thanks,
Sasha