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aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=zaclys.net header.s=default header.b=mknYsgP2; spf=pass (aspmx1.migadu.com: domain of bug-guix-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=bug-guix-bounces@gnu.org X-Migadu-Spam-Score: -5.00 Authentication-Results: aspmx1.migadu.com; dkim=fail ("headers rsa verify failed") header.d=zaclys.net header.s=default header.b=mknYsgP2; dmarc=pass (policy=none) header.from=gnu.org; spf=pass (aspmx1.migadu.com: domain of bug-guix-bounces@gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=bug-guix-bounces@gnu.org X-Migadu-Queue-Id: 5DF2A17C4E X-Spam-Score: -5.00 X-Migadu-Scanner: scn0.migadu.com X-TUID: Tr1OC/tDLSvA --=-Fin6oTue5EKmt0EG1/mg Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hello! Please see: -=20 https://www.gnu.org/software/libc/manual/html_mono/libc.html#Hardware-Capab= ility-Tunables - https://www.phoronix.com/scan.php?page=3Dnews_item&px=3Dglibc-hwcaps-RFC - https://gcc.gnu.org/onlinedocs/gcc/Function-Multiversioning.html This could help GNU Guix create binaries that include multiple code paths for several CPU features in the same binary and selecting the best at runtime when the binary is run. It is the best fit for GNU Guix because it means we can still use substitutes and profit from specialized optimizations without parameterized packages or each user adding "-march=3Dnative" to CFLAGS (breaking reproducibility). 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