Re: XenServer Xen-4.5 (-rc3ish) testing

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 09/12/14 08:46, Jan Beulich wrote:
>> We have certain machines which are showing reliable failure to boot
>> under Xen-4.5, where they worked with 4.4.  Symptoms range from the dom0
>> kernel crashing before printing anything, to complaining that the initrd
>> is corrupt when attempting to decompress.  This appears to be hardware
>> specific.
> Any chance this is C-state related, just like narrowed down to for
> http://lists.xenproject.org/archives/html/xen-devel/2014-11/msg00228.html?
> I.e. Westmere Xeons being affected? If not, this would seem rather
> worrying to me (read: a release blocker). And even if so, a workaround
> would be minimally needed. Otoh you didn't report so for earlier RCs -
> was that just because the testing scope was more narrow then, or can
> we imply that this is a recently introduced regression?
>
> Jan
>

I very much doubt it.  We blanket set max cstate to 1 on that era of
hardware, because the existing workarounds in Xen still experimentally
don't work.

https://github.com/xenserver/xen-4.4.pg/blob/master/detect-nehalem-c-state.patch

The first system I am looking at with a view to fixing is a SandyBridge
EN IBM Blade.

~Andrew