Re: [Xen-devel] What is the state of blktap2?

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Thu, Jan 21, 2010 at 06:13:46PM -0500, David P. Quigley wrote:
> On Fri, 2010-01-22 at 00:59 +0200, Pasi Kärkkäinen wrote:
> > On Fri, Jan 22, 2010 at 12:55:52AM +0200, Pasi Kärkkäinen wrote:
> > > On Thu, Jan 21, 2010 at 05:46:05PM -0500, David P. Quigley wrote:
> > > > On Fri, 2010-01-22 at 00:38 +0200, Pasi Kärkkäinen wrote:
> > > > > On Thu, Jan 21, 2010 at 05:27:45PM -0500, David P. Quigley wrote:
> > > > > > I'm currently working on moving storage services into their own 
> > > > > > domain
> > > > > > and I've been looking at blktap2. I've been trying to get an image
> > > > > > mounted with blktap2 and for some odd reason and tapdisk2 keeps 
> > > > > > hanging
> > > > > > instead of quitting at the end. I haven't removed any of the storage
> > > > > > startup code at this point so everything should be as it normally 
> > > > > > is in
> > > > > > xen-unstable. Is this a known bug? Are there some requirements on
> > > > > > blktap2 that I'm possibly not meeting? Is there anything in 
> > > > > > particular
> > > > > > that I should be looking at to try to debug the problem?
> > > > > > 
> > > > > 
> > > > > What kernel are you using? pv_ops dom0 kernel doesn't have working 
> > > > > blktap2 yet..
> > > > > linux-2.6.18-xen has working blktap2 support.
> > > > > 
> > > > > -- Pasi
> > > > 
> > > > I'm using the patches maintained by Andrew Lyon that are applied to
> > > > 2.6.31.10. These are supposedly based on the OpenSUSE patches and can be
> > > > found at http://code.google.com/p/gentoo-xen-kernel/downloads/list. I
> > > > need a more recent kernel version so the 2.6.18 dom0 kernel isn't an
> > > > option for me.
> > > > 
> > > 
> > > Ok. I'm not sure if those OpenSUSE patches have blktap2 support included?
> > > I know that at least Citrix XenServer, XCP and XCI 2.6.27 kernels do have 
> > > blktap2.
> > > 
> > > See:
> > > http://wiki.xensource.com/xenwiki/XenDom0Kernels
> > > 
> > 
> > More details about the pv_ops dom0 kernel (2.6.31.6 currently): It has 
> > initial version 
> > of blktap2 patches, but they'd need some debugging, because they're not yet 
> > working.
> > 
> > -- Pasi
> 
> 
> Looking under drivers through a make menuconfig on the pvops kernel I
> don't see an entry for blktap2. I just see the entry for blktap. I know
> that blktap2 was supposed to replace blktap but in the Novell patches
> they are two separate config options and I don't seem to be seeing the
> second on in the pvops kernel. Do I just enable blktap under drivers and
> use tap:tapdisk:<type> in the domU config to use blktap2?
> 

See:
http://git.kernel.org/?p=linux/kernel/git/jeremy/xen.git;a=shortlog;h=xen/master

Commits like:

2009-12-10      Jeremy Fitzhardinge     Merge branch 'xen/dom0/backend/blktap2' 
into xen/master
2009-12-10      Jeremy Fitzhardinge     xen/blktap2: don't init on non-Xen 
system
2009-12-04      Ian Campbell    blktap: cleanup usage of sysfs
2009-12-04      Ian Campbell    blktap: wean off of use of the BlkBack pageflag.
2009-12-04      Ian Campbell    Port blktap2 from 2.6.18 to tip.
2009-12-04      Ian Campbell    Add build infrastrucuture for blktap2.
2009-12-04      Ian Campbell    patch 03-blktap2-patch
2009-12-04      Ian Campbell    patch 02-blkback-pagemap-patch
2009-12-04      Ian Campbell    patch 01-blktap-patch

I haven't tried it myself yet..

-- Pasi


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