[Seirdy]

Many hyperscalar server setups use POWER8/POWER9 CPUs. 4 logical processes per core (and 8 with the upcoming 15-core POWER10 configurations) are pretty useful when measuring perf-per-watt.

The Talos is currently the only fully libre computer available for high-perf computing, and it uses POWER9 CPUs. If you want a fully free CPU, your choices are either very dated CPUs or POWER.

Many distros (inc. Debian, and most source-based ones) support ppc64/POWER officially quite well and go out of their way to ensure a high degree of portability.

[gnufx]

Actually, SMT8 P8 and P9 is documented, though it seems rare. Our HPC systems are only SMT4, anyhow.

Yes, you can just install most of at least Debian, Fedora, RHEL, at least, though it needs an "alt" kernel on RHEL7 P9. There are a few things which haven't been ported, mainly due to assembler, I guess. (PRoot and DMTCP are two I know.) Even x86 SIMD intrinsics will largely work, if not necessarily very efficiently.

[kilodeca]

By Libre computer do you mean the entire system, hardware and firmware?

[Seirdy]

Hardware: not necessarily. Firmware: yes.

[lkcl]

we'll be going as far as is practical and pragmatic with the actual hardware, and still actually meet user-expectations. firmware, bootloader, OS, drivers, BIOS: definitely.