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Fri, 09 Dec 2022 04:21:19 -0800 (PST) Date: Fri, 9 Dec 2022 07:21:17 -0500 From: Darius Rad To: Florian Weimer Cc: Andrew Waterman , Palmer Dabbelt , Vineet Gupta , stillson@rivosinc.com, Paul Walmsley , anup@brainfault.org, atishp@atishpatra.org, guoren@kernel.org, Conor Dooley , greentime.hu@sifive.com, vincent.chen@sifive.com, andy.chiu@sifive.com, arnd@kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, bjorn@kernel.org, libc-alpha@sourceware.org, christoph.muellner@vrull.eu, Aaron Durbin , linux@rivosinc.com Subject: Re: RISCV Vector unit disabled by default for new task (was Re: [PATCH v12 17/17] riscv: prctl to enable vector commands) Message-ID: Mail-Followup-To: Florian Weimer , Andrew Waterman , Palmer Dabbelt , Vineet Gupta , stillson@rivosinc.com, Paul Walmsley , anup@brainfault.org, atishp@atishpatra.org, guoren@kernel.org, Conor Dooley , greentime.hu@sifive.com, vincent.chen@sifive.com, andy.chiu@sifive.com, arnd@kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, bjorn@kernel.org, libc-alpha@sourceware.org, christoph.muellner@vrull.eu, Aaron Durbin , linux@rivosinc.com References: <877cz0nbce.fsf@oldenburg.str.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <877cz0nbce.fsf@oldenburg.str.redhat.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221209_042123_405254_FB09B547 X-CRM114-Status: GOOD ( 11.49 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, Dec 09, 2022 at 11:02:57AM +0100, Florian Weimer wrote: > * Andrew Waterman: > > > This suggests that ld.so, early-stage libc, or possibly both will need > > to make this prctl() call, perhaps by parsing the ELF headers of the > > binary and each library to determine if the V extension is used. > > If the string functions use the V extension, it will be enabled > unconditionally. So I don't see why it's okay for libc to trigger this > alleged UAPI change, when the kernel can't do it by default. > Because the call to enable can fail and userspace needs to deal with that. // darius _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv