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Sun, 19 Apr 2020 17:29:13 -0700 (PDT) Received: from localhost ([203.185.249.170]) by smtp.gmail.com with ESMTPSA id t12sm19938251pgm.37.2020.04.19.17.29.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Apr 2020 17:29:13 -0700 (PDT) Date: Mon, 20 Apr 2020 10:27:58 +1000 From: Nicholas Piggin Subject: Re: [musl] Powerpc Linux 'scv' system call ABI proposal take 2 To: Nicholas Piggin via Libc-alpha , Szabolcs Nagy References: <1586931450.ub4c8cq8dj.astroid@bobo.none> <20200415225539.GL11469@brightrain.aerifal.cx> <1586994952.nnxigedbu2.astroid@bobo.none> <20200416095800.GC23945@port70.net> In-Reply-To: <20200416095800.GC23945@port70.net> MIME-Version: 1.0 Message-Id: <1587341904.1r83vbudyf.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: libc-dev@lists.llvm.org, Rich Felker , linuxppc-dev@lists.ozlabs.org, musl@lists.openwall.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Excerpts from Szabolcs Nagy's message of April 16, 2020 7:58 pm: > * Nicholas Piggin via Libc-alpha [2020-04-16 = 10:16:54 +1000]: >> Well it would have to test HWCAP and patch in or branch to two=20 >> completely different sequences including register save/restores yes. >> You could have the same asm and matching clobbers to put the sequence >> inline and then you could patch the one sc/scv instruction I suppose. >=20 > how would that 'patch' work? >=20 > there are many reasons why you don't > want libc to write its .text I guess I don't know what I'm talking about when it comes to libraries.=20 Shame if there is no good way to load-time patch libc. It's orthogonal to the scv selection though -- if you don't patch you have to=20 conditional or indirect branch however you implement it. Thanks, Nick