Re: [PATCH 4/9] automation: Add Arm containers to containerize script

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Fri, Sep 23, 2022 at 03:23:26PM -0700, Stefano Stabellini wrote:
> On Fri, 23 Sep 2022, Michal Orzel wrote:
> > Hi Anthony,
> > 
> > On 23/09/2022 15:56, Anthony PERARD wrote:
> > > 
> > > 
> > > On Thu, Sep 22, 2022 at 03:40:53PM +0200, Michal Orzel wrote:
> > >> Script automation/scripts/containerize makes it easy to build Xen within
> > >> predefined containers from gitlab container registry. However, it is
> > >> currently not possible to use it with Arm containers because they are not
> > >> listed in the script. Populate the necessary entries.
> > > 
> > > FYI, those entry are just helper/shortcut/aliases, you can use any
> > > arbitrary container with the script, it just more annoying.
> > > 
> > > Your patch here allows to write:
> > >     CONTAINER=unstable-arm64v8 automation/scripts/containerize
> > > but you could write the following instead, for the same result:
> > >     CONTAINER=registry.gitlab.com/xen-project/xen/debian:unstable-arm64v8 
> > > automation/scripts/containerize
> > > 
> > > I wonder if the script could select the right container base on the
> > > architecture of the host, because "alpine" and "alpine-arm64v8" will not
> > > both work on the same machine. It might be nice to just choose "alpine"
> > > and the script would select the x86 or arm container automagically. Just
> > > an idea, no need to do anything about it.
> > I'm not in favor of adding the automatic selection based on the host.
> > The reason is that on x86 you can run both x86 and e.g. Arm containers.
> > You just need to use register qemu-user-static [1] to perform emulation.
> > This is something widely used and I use that to test Arm images/containers 
> > on x86 host.
> > So you can run both alpine and alpine-arm64v8 on the same machine.
> 
> Yeah and modern Docker sets up qemu-user-static automatically without
> the user having to do anything. Anthony, you can try it yourself: you
> should be able to just:
> 
>   docker run -it registry.gitlab.com/xen-project/xen/debian:unstable-arm64v8
> 
> on your x86 host if you have a docker new enough

No, it isn't so easy, there is at least one step that might be needed,
actually having qemu-user-static on the machine.

But thanks to both of you, I've learned about qemu-user-static, and that
it isn't necessarily complicated to setup. It is actually very easy to
setup once we know what to look for, I've just had to install a packaged
called "qemu-user-static" and that's all that was needed for the above
command line to work. Installing that package worked on two different
Linux distribution for me (on a derivative of Debian stable and on Arch
Linux) so it's likely to work in many cases, at least on x86.

Cheers,

-- 
Anthony PERARD