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From:   Heiko =?ISO-8859-1?Q?St=FCbner?= <heiko@sntech.de>
To:     Palmer Dabbelt <palmer@dabbelt.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Conor Dooley <conor@kernel.org>
Cc:     Tom Rix <trix@redhat.com>,
        Conor Dooley <conor.dooley@microchip.com>,
        Dao Lu <daolu@rivosinc.com>, Guo Ren <guoren@kernel.org>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
        llvm@lists.linux.dev
Subject: Re: [PATCH 2/2] riscv: fix detection of toolchain Zihintpause support
Date:   Thu, 06 Oct 2022 20:07:07 +0200
Message-ID: <2599561.BddDVKsqQX@diego>
In-Reply-To: <20221006173520.1785507-3-conor@kernel.org>
References: <20221006173520.1785507-1-conor@kernel.org> <20221006173520.1785507-3-conor@kernel.org>
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Am Donnerstag, 6. Oktober 2022, 19:35:21 CEST schrieb Conor Dooley:
> From: Conor Dooley <conor.dooley@microchip.com>
> 
> It is not sufficient to check if a toolchain supports a particular
> extension without checking if the linker supports that extension
> too. For example, Clang 15 supports Zihintpause but GNU bintutils
> 2.35.2 does not, leading build errors like so:
> 
> riscv64-linux-gnu-ld: -march=rv64i2p0_m2p0_a2p0_c2p0_zihintpause2p0: Invalid or unknown z ISA extension: 'zihintpause'
> 
> Add a TOOLCHAIN_HAS_ZIHINTPAUSE which checks if each of the compiler,
> assembler and linker support the extension. Replace the ifdef in the
> vdso with one depending on this new symbol.
> 
> Fixes: 8eb060e10185 ("arch/riscv: add Zihintpause support")
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

Reviewed-by: Heiko Stuebner <heiko@sntech.de>