Re: "make check-acceptance" takes way too long

[Stefano Brivio]

Hi,

On Tue, 25 Jan 2022 10:20:11 +0100
Gerd Hoffmann <kraxel@redhat.com> wrote:

>   Hi,
> 
> > IMHO the ideal scenario would be for us to have a kernel, initrd
> > containing just busybox tools for the key arch targets we care
> > about. Those could be used with direct kernel boot or stuffed
> > into a disk iamge. Either way, they would boot in ~1 second,
> > even with TCG, and would be able to execute simple shell scripts
> > to test a decent amount of QEMU functionality.  
> 
> I have some test images based on buildroot which are essentially that.
> https://gitlab.com/kraxel/br-kraxel/
> 
> Still a significant download, but much smaller than a full fedora or
> ubuntu cloud image and it boots much faster too.  Not down to only one
> second though.

I'm not sure you can recycle something from it, but my (ugly) approach
to make this fast (for a different purpose -- I'm using qemu to run
tests in guests, not testing qemu) is to build an initramfs by copying
the host binaries I need (a shell, ip, jq) and recursively sourcing
libraries using ldd (I guess I mentioned it's ugly).

No downloads, systemd, dracut, etc., guest boots in half a second
(x86_64 on x86_64, KVM -- no idea with TCG). Host kernel with a few
modules packed and loaded by a custom init script.

If you're interested, you can see it in operation at 3:11:17 (ah, the
sarcasm) of: https://passt.top/passt/about/#continuous-integration
(click on the "udp/pasta" anchor below, it's a few seconds in), or in
slow motion at 0:51 of https://passt.top/passt/about/#passt_2.

It's basically:

  git clone https://mbuto.lameexcu.se/mbuto/ && cd mbuto
  ./mbuto -c lz4 -p passt -f img # Profiles define sets of binaries
  ${qemu} -kernel /boot/vmlinuz-$(uname -r) -initrd img

-- 
Stefano