On Sun, Jul 12, 2020 at 11:49 PM Florian Weimer <fwei...@redhat.com> wrote: > > * H. J. Lu: > > > Looks good. I like it. > > Thanks. What do you think about Level B? Should we keep it?
Please drop Level B. > > My only concerns are > > > > 1. Names like “x86-100”, “x86-101”, what features do they support? > > I think we can add more diagnostic output to ld.so --help. My patch > does not show individual CPU flags, but I agree this could be useful. > (It's not needed for the legacy HWCAP subdirectories because in general, > those are named & defined by the kernel, not by individually named CPU > feature flags.) > > > 2. I have a library with AVX2 and FMA, which directory should it go? > > > > Can we pass such info to ld.so and ld.so prints out the best directory > > name? > > I think this would require generating matching GNU property notes (list > the CPU features required by the binary). Once we have that, we can add I have turned on -mx86-used-note=yes by default for binutils 2.36. I will add more ISAs bits after we determine which ISAs will be used. But compilers need to generate GNU_PROPERTY_X86_ISA_1_NEEDED property. > something to binutils or indeed ld.so to analyze them and print the > recommended directory. But I think this is something that could come > later. > > We can also write a GCC header which looks at macros such as __AVX2__ > and prints a #warning with the recommended directory name. Checking for > excess flags will be tricky in this context, though, and if we miss > something, a wrong recommendation will be the result. > > Thanks, > Florian -- H.J.
