On Tue, Oct 18, 2022 at 12:47 PM Ulrich Mueller <u...@gentoo.org> wrote: > > >>>>> On Tue, 18 Oct 2022, David Seifert wrote: > > > What if I want to build Gentoo on an old AMD Thunderbird which has > > neither SSE1 nor the more important SSE2? > > The -mfpmath=sse option is a no-op if the CPU doesn't support SSE, > i.e. it will use 387 arithmetics nevertheless.
I don't really see an "effective" way to deploy this via profiles on x86. We could add it to the default CFLAGS setting in profiles/arch/x86/make.defaults. However, we also default to -march=i686 there, and that doesn't support SSE or SSE2. Also, the entire CFLAGS variable is likely to be overridden by the CFLAGS setting in /etc/make.conf. The CFLAGS_x86 profile variable is only used by the multilib_toolchain_setup function in multilib.eclass. In other words, it only affects ebuilds that utilize the multilib eclasses to build libraries for multiple ABIs. That covers all 32-bit libraries on amd64, but doesn't cover all packages on x86.
