QEMU 6.0+ in 4.15 and 4.14 (Re: preparations for 4.15.1 and 4.13.4)

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

Anthony PERARD writes ("Re: preparations for 4.15.1 and 4.13.4"):
> Can we backport support of QEMU 6.0 to Xen 4.15? I'm pretty sure
> distributions are going to want to use the latest QEMU and latest Xen,
> without needed to build two different QEMU binaries.

I think this is appropriate.  Xen 4.15 is still now, and there was an
unfortunate interaction between release dates.  Your argument makes
sense.

> [XEN PATCH v2 0/8] Fix libxl with QEMU 6.0 + remove some more deprecated 
> usages.
> <20210511092810.13759-1-anthony.perard@xxxxxxxxxx>
> Commits: d5f54009db^..fe6630ddc4
> 
> Some more QEMU 6.0 fixes
> <20210628100157.5010-1-anthony.perard@xxxxxxxxxx>
> Commits: 217eef30f7  3bc3be978f

So I have queued all these.

> Also, Olaf want them to be backported to 4.14, see
>     <20210629095952.7b0b94c1.olaf@xxxxxxxxx>

I'm unsure about this.  The diff seems moderately large.  Also, are we
sure that it wouldn't break anything other than very old qemu ?  OTOH
compat problems with newer qemu are indeed a problem especially for
distros.

I'm currently leaning towards "no" but I am very open to being
convinced this is a good idea.

Ian.