Re: [Xen-devel] Problem with starting guest (para_virt dom0)

[Adam Wendt <thelsdj@xxxxxxxxx>]

On Thu, Jan 15, 2009 at 12:04 AM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

On Wed, 2009-01-14 at 23:56 -0800, Adam Wendt wrote:
> Hi,
>
> I've managed to get a para_virt dom0 running on my x86_64 system but
> having problems starting a guest.  First problem was that xenstore
> client programs weren't able to communicate over xenbus (xs_write_all
> hitting its return false branch) still not sure why this is happening.
> I was able to at least get xenstore working by hacking the client to
> use the normal socket by default.

Perhaps you need to enable xenfs in your kernel build and mount it
on /proc/xen in order to gain access to /proc/xen/xsd*?

Not sure if you actually meant /proc/xen/xsd or that was just a mistype, but xs_lib.c tries to use /proc/xen/xenbus which _does_ exist in /proc/xen/ but like I said above the xs_write_all hits the return false branch so something wrong with the filehandle or who knows what, for now I was able to get rudimentary xenstore functionality working defaulting to the socket interface, but when I try to start a guest I get a bunch of:

xenstore-write: could not write path backend/vbd/1/770/hotplug-error
xenstore-write: could not write path backend/vbd/1/771/hotplug-error
xenstore-write: could not write path backend/vbd/1/770/hotplug-error

In the hotplug log and then guest creation errors out about failed hotplug. So still unable to start a guest.

> But now I'm getting:
> Error: [Errno 2] No such file or directory: '/proc/xen/balloon'
>
> Google only turned up reports that this is related to trying to give
> the guest too much memory, but xm info shows I have over 3.5G free and
> only trying to give 128M to the guest. Any other ideas what might be
> causing this?

pvops only supports balloon via a sysfs interface not proc. There is a
patch in xen-unstable.hg from Jeremy Fitzhardinge which fixes this but
you'll either need to use xen-unstable or backport it to whatever you
are using (it's pretty simple, IIRC).

Ok yea I switched back to xen-unstable for now, though not sure if unstable is causing my above xenstore-write error as I wasn't getting that on 3.3.1 (but was then getting the balloon error)

Adam

Ian.

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