Re: [Xen-devel] [PATCH 0/4] block/xen_disk: legacy code removal and cleanup

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, May 02, 2018 at 05:03:09PM +0100, Paul Durrant wrote:
> > -----Original Message-----
> > From: Anthony PERARD [mailto:anthony.perard@xxxxxxxxxx]
> > Sent: 02 May 2018 16:58
> > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; qemu-block@xxxxxxxxxx; qemu-
> > devel@xxxxxxxxxx; Stefano Stabellini <sstabellini@xxxxxxxxxx>; Kevin Wolf
> > <kwolf@xxxxxxxxxx>; Max Reitz <mreitz@xxxxxxxxxx>
> > Subject: Re: [PATCH 0/4] block/xen_disk: legacy code removal and cleanup
> > 
> > On Mon, Apr 30, 2018 at 01:01:35PM +0100, Paul Durrant wrote:
> > > The grant copy operation was added to libxengnttab in Xen 4.8.0 (released
> > > nearly 18 months ago) but the xen_disk PV backend QEMU is still carrying
> > > a significant amount of code purely to remain compatible with older
> > > versions of Xen.
> > >
> > > As can be inferred from the diff stats below, removing this support for
> > > older versions of Xen from QEMU reduces the size of the xen_disk source
> > by
> > > more than 350 lines (~25%). The majority of this is done in patches #1
> > > and #2. Further simplifications are made in patch #3 and then some
> > cosmetic
> > > work is done in patch #4.
> > 
> > FIY, I don't like this patch series. We've been checking that QEMU
> > builds against older version. I've check that it builds against 4.5 and
> > newer.
> > 
> 
> Ok, I can grant copy emulation in QEMU then should it not exist for the 
> particular Xen/OS combo.
> 
> > Also the fact that FreeBSD doesn't have support for grant copy probably
> > mean that it is too soon to remove the compatibility code from qemu.
> > 
> 
> On another thread I'd already agreed to emulate grant copy in libxengnttab 
> for those OS where it is not supported, but if you prefer it to be in QEMU 
> I'll put it there.

Yes, I think it will be better from QEMU point of view.

Thanks,

-- 
Anthony PERARD

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