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[Xen-devel] Re: [RFC PATCH v01] Xen PVSCSI drivers for pvops xen/stable-

To: Nathanael Rensen <nathanael@xxxxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [RFC PATCH v01] Xen PVSCSI drivers for pvops xen/stable-2.6.32.x kernel
From: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Date: Fri, 7 Jan 2011 10:26:56 +0000
Cc: Patrick Colp <pjcolp@xxxxxxxxx>, Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Olaf Hering <olaf@xxxxxxxxx>
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On Fri, 2011-01-07 at 10:03 +0000, Nathanael Rensen wrote:
> On 7 January 2011 06:35,  Pasi Kärkkäinen <pasik@xxxxxx> wrote:
> > Hello,
> >
> > http://pasik.reaktio.net/xen/patches/xen-pvscsi-drivers-linux-
> >
> > This is the first version of Xen PVSCSI drivers, both the scsiback backend 
> > and
> > scsifront frontend, ported from Novell SLES11SP1 2.6.32 Xenlinux kernel to
> > pvops xen/stable-2.6.32.x branch.
> >
> > -- Pasi
> That's great. Some comments based on my experience with pvusb:
> 1) You've added GNTST_eagain into include/xen/interface/grant_table.h.
> When porting the pvusb drivers I removed the "check and retry" loops
> based on GNTST_eagain because I noticed that netback and blkback don't
> do that. Looking at the grant_table code in xen-4.0-testing I don't
> think GNTST_eagain is used now. Perhaps someone with knowledge of the
> history of GNTST_eagain could help to clarify.

IIRC GNTST_eagain was added to the classic Xen trees but never forward
ported to pvops.

It's part of the page sharing paging work (so dom0 can deal with a
paged/shared guest rather than for paging of dom0 itself). I guess those
don't work with pvops kernels? CC'ing the guys who are working on that

(The presence of the use of msleep in the eagain case is a bit
terrifying. Stripping it out for now and redoing it might not be a bad


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