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

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 19/07/2010 13:19, "Tim Deegan" <Tim.Deegan@xxxxxxxxxxxxx> wrote:

>>> 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.

Thanks. The revised patch might be acceptable, but if possible we're better
off relying on undocumented xenstored behaviour than domU frontend behaviour
since the former we have full control over (albeit we now have two daemons
to consider). Really nice would be some kind of explicit reset command or
protocol, but in this context since there are no watches or pending requests
or anything, I guess whacking the xenstore page is sufficient engineering
effort.

 -- Keir



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