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

[Daniel P . Berrangé]

On Tue, Feb 01, 2022 at 07:31:39AM +0100, Stefano Brivio wrote:
> 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.

That is such a good idea, that it is exactly what I do too :-)

  https://gitlab.com/berrange/tiny-vm-tools/-/blob/master/make-tiny-image.py

it works incredibly well for the simple case of host-arch==guest-arch.

It could be made to work for foreign arch easily enough - just need
to have a foreign chroot lieing around somewhere you can point it
to.

Regards,
Daniel
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