On 12/19/24 3:08 PM, Palmer Dabbelt wrote:
I agree lacking B and V makes us very clearly uncompetitive in the space
where these sort of things matter (ie, binary compatible distros and
long term stability type things) -- the gap is just too big to close by
doing clever things in the hardware. Maybe just B and V isn't enough,
it's hard to tell, but lacking them seems pretty clearly uncompetitive.
I'm not sure B is so scary on the SW side of things, it's been mostly
performance issues we've been fixing. V is huge, though, and we've
generally found a bunch of V-related functional codegen bugs. Without
reliable hardware to test against (and do distro builds and such) it
just seems premature to declare that being as stable as the other ports
on the list.
It wouldn't take much to push me into agreeing to B -- it's not scary in
any way. There's just notable systems out there that don't implement B,
but I wouldn't mind leaving them behind for this change.
V has real performance concerns. I haven't tested it performance-wise
on the BPI recently, but when I last did the general rule of thumb was
the more vector you did, the worse it performed *especially* for FP.
jeff
