Re: Rust in Qemu BoF followup: Rust vs. qemu platform support

[Philippe Mathieu-Daudé]

On 9/17/21 6:04 PM, Warner Losh wrote:> wrt FreeBSD:
> 
> The main focus of the project is on AMD64 (x86_64) and ARM64 (aarc64). With
> ricsv64 being ascendant as well. i386 and armv7 are fading. ppc64 has
> strong,
> but episodic, interest as well. The rest are bit players.
> 
> i386 (i686 really), armv7 and riscv7 are the next tier of interest in
> FreeBSD
> land. i386 is confined to 32-bit VMs with only a few legacy hardware
> deployments
> still kicking. armv7 is more popular on embedded boards, some of which have
> a need to run qemu.

What part of QEMU is used there, user-emulation (likely IMO) or
system-emulation (unlikely) or both?

> riscv64 has a rust port that's being upstreamed, but not
> there yet and there's likely interest to run qemu on it for research
> projects.
> riscv64 isn't widely deployed but has a lot of developer interest /
> mindshare.
> sparc64 was removed from FreeBSD 13 and has been irrelevant for years.
> ppc 32 bit has some minor interest. mips has been fading fast and stands
> an excellent chance of being removed before FreeBSD 14 (which is currently
> slated for 2022). PowerPC 64 is hard to talk about... there's interest
> that comes
> and goes, but when it's around, it's quite intense. It's quite likely
> there will
> be interest to run qemu on ppc64 on FreeBSD, but that's much less certain.
> 
> So it all depends on what having rust means for those platforms that
> don't have
> it. Would it be a 'half a loaf' situation where the non-rust bits would
> be buildable
> but cool new drivers written in rust won't be? Or will it be so central
> that rust is
> table stakes to even start a qemu build? To be honest, I'm not sure this
> difference
> would greatly affect the above answer :).
> 
> Rust works really well on x86_64 and aarch64 (though there's more often
> a lag
> on the latter of a few weeks). I know of a rust riscv64 port, but that's
> just getting
> ready to upstream. No first-hand or second-hand clue on the rest.
> 
> FreeBSD tl;dr: x86_64 and aarch64 are must have. i386, armv7 and riscv64 are
> really nice to have. ppc64 might also be in that list, but that's less
> certain. The rest
> have little to no relevance.

Thanks for gathering this useful info!

> P.S I've been poking at people to get our QEMU aarch64 CI story in better
> shape than it is today... I'll have to continue to prompt those
> interested...
>