Re: Introduction + interest in a riscv64 port of GNU Mach/Hurd

Hey,

I'm happy to discuss (what I remember of) the AArch64 port design
questions and decisions we made. Incidentally, I'm also looking into
RISC-V (just learning basic things about it), so it would be
interesting to watch, and potentially participate, in a Mach porting
effort.

And a small rant of what I've seen this far: the 'la' instruction (and
the PIC/non-PIC terminology) makes no sense, what were they thinking?
Fortunately it's only a pseudo-instruction and we can always use 'lga'
and 'lla', or the actual instructions behind those, and ignore the
existence of 'la'. The 'gp' thing (and the linker relaxation around
it) only seem useful for firmwares and small kernels, and perhaps it'd
actually be useful for gnumach, but it does seem fairly useless for
userland (considering libraries), and there could be better ways to
make use of the register. I heard that some ABIs (Haiku, Android,
Fuschia?) are _not_ using x3 as gp, and there's official ELF support
for this (Tag_RISCV_x3_reg_usage), what would you all think about
potentially doing the same for riscv64-gnu userland?

Sergey