Hi folks,
In the hope this might be interesting for people...
I've just finished with my analysis of rebuilding the Debian archive for armel and armhf using arm64 build machines. I've been rebuilding the archive *specifically* to check if we would have any problems building our 32-bit Arm ports (armel and armhf) using 64-bit arm64 hardware. I might have found other issues too, but that was my goal.
Executive summary:
As far as I can see we're basically fine to use arm64 hosts for building armel and armhf, *so long as* those hosts include hardware support for the 32-bit A32 instruction set. As I've mentioned before in Debian, that's not a given on *all* arm64 machines, but there are sufficient machine types available that I think we should be fine. There are a couple of things we'll need to do in terms of setup.
See
https://blog.einval.com/2019/01/07#rebuilding_on_arm64
for the full article.
Cheers,