Re: Detection of hadware feature => please do not use signal

On Sun, Nov 24, 2024 at 1:09 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Oh, very interesting!  Maybe we need to try -march=armv8-a+crc+fp
> (or some spelling like that) if -march=armv8-a+crc doesn't work?

Hmm, they were talking about armv7-a, not armv8-a, but it seems
related... does it work?

The GCC docs give only +nofp, not +fp as an option for 32 bit armv8-a
(that is, under "ARM options", as opposed to "aarch64 options").  But
I guess GCC is pretty configurable and NetBSD targets some weird
hardware... as for why it could be like that (if not a mistake), it
looks like it might be technically possible for armv8 (including -a)
to lack FP in aarch32 state (unlike aarch64 state), but I went looking
for real existing 32-bit only armv8 chips lacking FP and found only
stuff like Cortex M23, and they're using armv8-m (embedded profile,
lots of other stuff missing or optional).  The weakest 32 bit-only
armv8-a chip I could find in a quick search was the Cortex A32 but it
looks like it has FP.  I don't know enough about any of this stuff to
guess what's going on here.