In reply to @alex:tunstall.xyz

I've measured ~22h for building an unregisterised GHC 9.2.8 booted via an unregisterised GHC 8.10.7 when running on VF2 (JH7110 SoC).
(Default flavour with profiled libraries, dynamic libraries, and documentation enabled.)

One minor difference to a typical RV64GC build is that I also enable Zba and Zbb.
I have no idea what performance impact this has on my hardware.

That a Milk-V Pioneer would take over 30h to do the same is surprising.

I just remembered that I have logs, so:

configurePhase completed in 1 minutes 37 seconds
buildPhase completed in 21 hours 32 minutes 2 seconds
installPhase completed in 8 minutes 33 seconds
fixupPhase completed in 4 minutes 7 seconds

(unpack and patch phases don't appear to log timings.)