Re: [Xen-devel] [PATCH 5/5] xen: Add xenbusd device driver

[Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>]

On 11/28/2011 01:52 PM, Bastian Blank wrote:
> On Mon, Nov 28, 2011 at 02:37:23PM -0400, Konrad Rzeszutek Wilk wrote:
>> On Sun, Nov 27, 2011 at 11:07:08PM +0100, Bastian Blank wrote:
>>> +   if (!xen_initial_domain())
>>
>> With the disgregated domains (and the patches that Daniel posted), I
>> think this needs to relax a bit. Perhaps just make it 'xen_domain'?

What we want is for this device to appear any time xenstored is in
the local domain. In xenbus_probe, I use the xen_start_info structure
to determine this - xen_start_info->store_evtchn is nonzero if there
is a remote xenstored.

> Right now, xenstored needs to run where the communication ring is
> located. And this ring is allocated in dom0. How would any domU run
> without xenstored available?
> 

A domU can run just fine without xenstored available - in particular,
it is possible to run xenstored itself in a domU. This requires either
dom0 patches to enable xenbus to be relocated after launch, or for
xenstored to be started prior to the Linux initial domain. In both
cases, it also requires a modified domain builder that doesn't talk
to xenstored.

This change is only important if xenstored is running in a Linux-based
stub domain instead of a minios-based one.

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