[libre-riscv-dev] PowerISA 3.1 (Power10) spec released

[Lauri Kasanen]

On Tue, 12 May 2020 08:50:09 +0100
Luke Kenneth Casson Leighton <lkcl at lkcl.net> wrote:

> On Tue, May 12, 2020 at 7:00 AM Lauri Kasanen <cand at gmx.com> wrote:
>
> > level. However the Linux level requires SIMD.
>
> this is more serious.  the implementation burden of POWER SIMD
> compliance is absolutely massive.  a quick count from figure 91 i
> estimate 600 instructions dedicated to INT and FP SIMD.
>
> the scalar instruction set is much more manageable: there's 378
> opcodes from microwatt CSV files, then there's 20 FP LD/ST, and
> estimated 70 or so FP arithmetic and 8 or so status registers.

It's just a name though, even the doc says you can run Linux on the
lower levels. It's fine for libresoc to be at the int+fp level, and
include optional features from above that are useful. I just wanted to
point out the BE/LE requirement as it surprised me at least.

BE for instructions is not full BE, as data changes too.

- Lauri