Hi Sébastien, On Tue, Jul 13, 2021 at 2:04 PM Sébastien Villemot <sebast...@debian.org> wrote: > > Hi, > > The wiki page that synthesizes architecture specificities indicates > that Altivec is included in the baseline for the ppc64 port: > https://wiki.debian.org/ArchitectureSpecificsMemo#ppc64 > > However my understanding is that this port supports any powerpc64 CPU, > including some that don’t have Altivec (e.g. POWER4 or POWER5). This is > also what the main wiki page for PPC64 says: > https://wiki.debian.org/PPC64 > > Can someone please clarify the situation? > > (I’m asking because I’m the maintainer of the openblas package, and > knowing whether Altivec is available or not, and more generally what is > in the baseline, is essential for proper packaging).
I do not believe that you can do much as a packager. You cannot assume anything on the target arch. You need to do the same thing as ffmpeg is doing for avx2/sse4 on amd64, you need to do runtime detection. So unless upstream is doing something very clever you cannot compile blas using any of the fancy altivec instructions :( The man page for ld.so mentions something about optimized libraries (search for "/usr/lib/sse2/"), but this is currently not in use in Debian (AFAIK). 2cts
