Re: [Xen-devel] [xen-unstable test] 16788: regressions - FAIL

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.03.13 at 18:14, Tim Deegan <tim@xxxxxxx> wrote:
> At 16:34 +0000 on 04 Mar (1362414893), Jan Beulich wrote:
>> So apparently xl doesn't set the shadow size early enough, as by
>> the time domain creation fails, I can't observe any invocation of
>> shadow_domctl(), i.e. also not libxl__arch_domain_create()'s
>> XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION.
> 
> Hmmm.  libxl__arch_domain_create() seems to be called from
> domcreate_attach_pci(), of all places -- oh, because the whole
> process is a series of tail-calls -- and that's very late in
> domain build.  I'm pretty sure xend allocated shadow RAM up front.

While I having looked at this last must date back a couple of years,
I'm also relatively certain that xend did this earlier.

> Or maybe we're only now getting to see VMs big enough that this is a
> problem.

Less likely. But presumably the test system should be using bigger
guests, or have a case of a bigger guest added?

Ian - any chance you could look into both the xl and the test
suite aspects?

>> That's all very unsatisfying, the more with the failure not easily
>> being recognizable as an out of (shadow) memory related one.
> 
> How annoying.  I'll add at least a one-time console warning and look
> into some more sensible error propagation

Thanks!

>> And in the end, Tim, it doesn't look like Linux HVM guests exercise
>> the cross-page-boundary emulation path, so I can't really test the
>> code. Shall I put it in nevertheless, or would you be able to give
>> this a go beforehand?
> 
> Unfortunately there's no chance I can do any testing this week before
> Thursday.  I think the patch should go in anyway -- it's not going to
> make the situation any worse for VMs that do hit that path.

Okay, committed - after having sent the mail I too realized that
having the patch in won't make matters worse.

Jan


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