Re: [PATCH] [RFC] qemu-upstream: add discard support for xen_disk

[Olaf Hering <olaf@aepfle.de>]

On Fri, Jan 17, Stefano Stabellini wrote:

> On Fri, 17 Jan 2014, Olaf Hering wrote:
> > On Fri, Jan 17, Stefano Stabellini wrote:
> > 
> > > On Thu, 9 Jan 2014, Olaf Hering wrote:
> > > > The discard support is enabled unconditionally. But it would be worth to
> > > > have a knob to disable it in case the backing file was intentionally
> > > > created non-sparse to avoid fragmentation.
> > > > How could this be knob be passed from domU.cfg:disk=[] to the actual
> > > > qemu process?
> > > 
> > > It would need to be on xenstore, because that is the only per-disk
> > > interface xen_disk is listening to.
> > 
> > I figured that out. There are already script=, backend= and other knobs.
> > I will see how to add a discard=on|off to libxl and write that to the
> > xenstore backend node so qemu can get it from there.
> > What property name do you suggest? I have something like
> > "toolstack-option-discard" in mind.
> 
> discard_enabled?

Isnt that name too generic? In the end that node is used also by backend
and frontend.

Olaf