Create an arm* VM

Create a jessie/stretch/buster-elts armhf VM, to run and debug a failing package build (or testsuite):

sudo apt install arch-test uidmap binfmt-support \
  qemu-system-arm qemu-user-static

DIST=buster
ARCH=armhf
debvm-create -r $DIST -o $DIST-$ARCH.debvm -k path/to/ssh_id.pub \
  --size=2G -- \
    --architecture=$ARCH \
    --keyring=/publicly-readable/path/to/freexian.gpg \
    http://deb.freexian.com/extended-lts \
    --include=linux-image-5.10-XXX
# Note: the initramfs step may take several minutes

The part after -- is passed to mmdebstrap.

Replace XXX by the kernel for your target architecture (armmp for armhf). Using an ELTS kernel backport is required to detect /dev/vda / virtio_blk for jessie and stretch.

Optionally append --include=strace,vim,....

Now run the VM:

debvm-run -i $DIST-$ARCH.debvm --sshport 2222 -- -m 3G

The part after -- is passed to qemu.

Further customizations possible. You can add xxx-lts-proposed. You can add the target package. man debvm-create has a few more details.

Limitations:

  • The VM is not hardware-accelerated and quite slow (CPU and I/O, by an order of magnitude). Using eatmydata helps a little. Same for mount -t tmpfs none /mnt/workdir -o size=2G, but the main bottleneck appears to be the CPU more than the disk.

  • The VM does not behave exactly like the real buildd hardware, different errors may occur.

Troubleshooting

  • E: unable to pick chroot mode automatically (use –mode for manual selection)

Add e.g. --mode=unshare at the end of the debvm-create line, or run through sudo.

  • The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY A07310D369055D5A

Ensure freexian.gpg is readable by any user on your system (e.g. not in your home dir).

Also check the output of gpg:

$ gpg --list-key --no-default-keyring --keyring $PWD/freexian-archive-extended-lts.gpg
/.../freexian-archive-extended-lts.gpg
-------------------------------------------------------
pub   rsa4096 2018-05-28 [SC] [expires: 2027-12-05]
      AB597C4F6F3380BD4B2BEBC2A07310D369055D5A
uid           [ unknown] Extended LTS Repository <sysadmin@freexian.com>

  • passwd: Cannot determine your user name.

Apply https://salsa.debian.org/helmutg/debvm/-/commit/e4ecc7f745c54a765eff8eff59fc2e9a03371f2e

  • init fails to mount disk, /dev/vda not present (jessie, stretch)

Use a kernel backport: --include=linux-image-5.10-armmp (armhf) or --include=linux-image-5.10-arm64.

Other resources

Pre-built images, with external kernel and initrd:

Manual install from ISO: