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

To: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [RFC PATCH v01] Xen PVSCSI drivers for pvops xen/stable-2.6.32.x kernel
From: Pasi Kärkkäinen <pasik@xxxxxx>
Date: Fri, 7 Jan 2011 12:32:58 +0200
Cc: Patrick Colp <pjcolp@xxxxxxxxx>, Jeremy Fitzhardinge <jeremy@xxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Olaf Hering <olaf@xxxxxxxxx>, Nathanael Rensen <nathanael@xxxxxxxxxxxxxxxx>
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On Fri, Jan 07, 2011 at 10:26:56AM +0000, Ian Campbell wrote:
> 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.

Yeah, I noticed GNTST_eagain was missing from pvops, so I just blindly 
copied it from Xenlinux to pvops.. 

With the first version of PVSCSI for pvops I tried to do minimal
changes, just enough to make it compile.. 

So that stuff needs some more attention.

> 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
> stuff.
> (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
> plan)

-- Pasi

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