[libvirt] Bump tar format?

[Andrea Bolognani]

On Mon, 2016-06-13 at 09:57 +0100, Daniel P. Berrange wrote:
> > Since RHEL5 support has been dropped for a while now, maybe it's time to
> > revisit changing the tar format
> 
> Yep, IIUC we should be fine for require pax support for the vintage of
> Linux we required.  *BSD should be fine too, so IIUC, their tar version
> uses libarchive which supports pax.  Windows has 7-zip which can do pax
> and of course cygwin. Finally OS-X has the pax command and support in
> the apple archive utility.
> 
> So I think we're be fine to require it.
> 
> While, we're changing this, I think we should probably take the opportunity
> to also switch over to using 'xz' as our compression format, instead of gz.
> Consider the 1.3.5 release compressed with different formats:
> 
>  35109092  libvirt-1.3.5.tar.gz
>  25573966  libvirt-1.3.5.tar.bz2
>  12112612  libvirt-1.3.5.tar.xz
> 
> Those results seem pretty compelling to me :-)

xz compression sure takes a lot of time!

I vote yes to both, though :)

-- 
Andrea Bolognani
Software Engineer - Virtualization Team