[libvirt] [libvirt PATCH] qemu: Support discard for disk

[Daniel P. Berrange]

On Wed, May 15, 2013 at 02:56:03PM +0200, Paolo Bonzini wrote:
> Il 14/05/2013 14:44, Osier Yang ha scritto:
> > QEMU introduced "discard" option for drive since commit a9384aff53,
> > 
> > <...>
> > @var{discard} is one of "ignore" (or "off") or "unmap" (or "on") and
> > controls whether @dfn{discard} (also known as @dfn{trim} or @dfn{unmap})
> > requests are ignored or passed to the filesystem.  Some machine types
> > may not support discard requests.
> > </...>
> > 
> > This patch exposes the support in libvirt.
> > 
> > QEMU supported "discard" for "-drive" since v1.5.0-rc0:
> 
> I would prefer to use ignore/unmap instead of off/on in libvirt.

If we think there's any chance QEMU might gain a 3rd possible
value for this setting, then I tend to agree with you that
avoiding off/on would be desirable.

Daniel
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