Re: armv6 support for rust?

[Havard Eidnes <he%NetBSD.org@localhost>]

> Right now we only build rust for armv7, but the RPI Zero and
> other cheapo Rapsberry Pi boards are v6. Since rust is becoming
> even more of a critical dependency (compare py-cryptography),
> it would be really nice to get rust for armv6.
>
> It can't be the only 32-bit arm port (like how we downgraded
> the 32-bit x86 one to i586 to support embedded boards), because
> backwards compatibility is less of a priority for the arm folks and
> newer hardware is missing deprecated instructions.
>
> It looks like there is already support upstream, so it just
> falls on there being existing bootstrap tarballs, hopefully? :)

I'll take a look at this, it may be as easy as it was when I
enabled the aarch4_be port earlier.

Related to this, I might need an armv6 VM to check if "native"
binaries can be built.  I currently run my armv7hf VM via

#!/bin/sh
SMP=4
MEM=4g
#  -kernel netbsd-GENERIC.ub -append root=ld4a
qemu-system-arm -M virt -smp $SMP -m $MEM \
  -drive if=none,file=disk.img,id=hd0 -device virtio-blk-device,drive=hd0 \
  -netdev type=user,id=net0,hostfwd=tcp::2222-:22,ipv6=off \
  -nographic \
  -device virtio-net-device,netdev=net0,mac=00:11:66:33:44:55 \
  -bios QEMU_EFI.fd

Any idea what I need to change to force this to be an armv6 host?
This may be a question of which "-cpu <value>" to use, and I'm
sufficiently un-familiar with the arm jungle to be able to
immediately realize which one of the various cortex variants to
use, for instance.

And which boot image should I start from?

Regards,

- Havard