[Xen-devel] Re: [PATCH] Re: cs:21768 causes guest spend more time on boot up

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 12:46 +0100 on 19 Jul (1279543585), Keir Fraser wrote:
> On 19/07/2010 11:55, "Tim Deegan" <Tim.Deegan@xxxxxxxxxxxxx> wrote:
> 
> >> Yes, I am still looking into it.  I think the address of the table is
> >> not causing it, though, so it might take some time to find the real
> >> cause.
> > 
> > The hang turned out to be entirely unrelated to the SMBIOS tables; the
> > xenbus client zeroes out teh xenstore ring entirely, and it looks like
> > newer dom0 xenbus backends can't handle that, so:
> 
> What would it have to do with an in-kernel driver? Doesn't the comms page
> only get looked at by [o]xenstored? In which case we could fix them.

Ah, so it does.  I assumed it was the kernel because that's all that
changed on my test box since I last tested this stuff.  I'm using the C
xenstored and its code looks like it should work fine with the page
getting zeroed under its feet.  I'll dig further.

Cheers,

Tim.

> 
>  -- Keir
> 
> > hvmloader: don't zero out the xenbus page.
> > Not all xenbus backends accept that gracefully.  Instead rely on the
> > xenbus frontend in the guest being able to start up with non-zero ring
> > offsets. 
> > 
> > Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
> 
> 

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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