There was a recent update-of-sorts regarding bootstrapping for matters of provenance:
but I’ve also been informed that it’s somewhat different from bootstrapping for cross-compilation.
[…] apparently there was some bug introduced after 7.6 and fixed around 8.x […] So I could not get 7.7 or 7.8 to build, and then either 7.10 or 7.12 already wanted a newer version.
GHC still has the old -fvia-c option (strictly for this purpose only, not intended for regular use) but it’s been a while since I’ve seen anyone try using it - I suggest contacting the GHC devs before attempting to use it…