[Libguestfs] Fedora Rawhide / libguestfs 1.23.14 now enables -cpu host, +kvmclock

[Richard W.M. Jones]

On Tue, Aug 06, 2013 at 04:38:59PM +0100, Richard W.M. Jones wrote:
> Passing '-cpu host' is meant to cause qemu to pass the same CPUID
> flags from the host up to the appliance.  The major benefit of this is
> that the appliance can use all CPU features available to optimize eg.
> checksumming, crypto, RAID XOR operations, zero fill.
> 
> However in practice this can cause strange problems on some hardware:
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=870071
> 
> This manifests itself as particular operations failing randomly,
> especially if RAID or crypto is involved.  If you enable debugging you
> would see a kernel stack trace similar to the one shown in the bug
> above (and possibly many other variations).
> 
> If you see anything like this, please file a bug.

Unfortunately I did see several problems, so I've modified the patch
so that -cpu host (or <cpu mode=host-model> for libvirt) is only used
when KVM [hardware virt acceleration] is available.  It didn't make
sense for TCG anyway.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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