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AW: RE: RE: RE: RE: RE: [Xen-devel] No C-States any longer...

To: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Subject: AW: RE: RE: RE: RE: RE: [Xen-devel] No C-States any longer...
From: Carsten Schiers <carsten@xxxxxxxxxx>
Date: Wed, 15 Jun 2011 11:03:58 +0200
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Yu, Ke" <ke.yu@xxxxxxxxx>
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Thanks for your support. 

So the plan is to run the very kernel (2.6.32.40 from Jeremy's git) natively, 
without Xen, and check 
what acpi.debug and my printks are reporting?

Would the other check be to change pr_id from -1 to 0 by some helper code in 
the right place?

Have I correctly understood that my BIOS seems to implement C-States through 
FADT instead of _CST, 
which is ok generally, but the FADT PBLK is not correctly set (maybe because it 
worries about the -1)?

By the way: 

  - I dom0_vcpus_pin and restrict Dom0 to only use one vcpu in xend-config.sxp
  - I used Xen/Debian Squeeze PVOPS Xen Kernel on the Intel Box
  - The same combo fails on the AMD box, latest PVOPS, too. Further testing 
done with latest PVOPS.

Everything used to work with Xen / 2.6.18 Dom0 Kernel, but I cannot check that, 
because it will not 
boot any longer, because it doesn't find the root system. I currently 
concentrate on the C-State 
issue.

Carsten.


----- Originalnachricht -----
Von: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Gesendet: Mit, 15.6.2011 10:39
An: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Cc: Carsten Schiers <carsten@xxxxxxxxxx> ; "Yu, Ke" <ke.yu@xxxxxxxxx> ; 
xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Betreff: RE: RE: RE: RE: RE: RE: [Xen-devel] No C-States any longer...

> From: Ian Campbell [mailto:Ian.Campbell@xxxxxxxxxx]
> Sent: Wednesday, June 15, 2011 4:35 PM
> 
> On Wed, 2011-06-15 at 09:11 +0100, Tian, Kevin wrote:
> > > From: Carsten Schiers [mailto:carsten@xxxxxxxxxx]
> > > Sent: Tuesday, June 14, 2011 4:27 AM
> > >
> > > One step further: the problem is that pr->pblk is not set, thus
> > > acpi_processor_get_power_info_fadt fails.
> > > Knowing this, I found an error in the ACPI_DEBUG output that
> > > corresponds:
> > >
> > > [   17.062739] processor_xen-0222 [00] xen_acpi_processor_get:
> Processor
> > > [-1:0]
> > > [   17.062902] processor_xen-0225 [00] xen_acpi_processor_get: No PBLK
> > > (NULL address)
> >
> > this looks a bit strange. how about the native log?
> >
> > >
> > > It does this for all processors. pr_id is always -1, pr->acpi_id
> > > counting up from 0 to 2.
> >
> > what's your dom0 vcpu number? and how about physical cpu?
> 
> Wasn't there some oddity in the Xen ACPI PM support due to the
> disconnect between VCPU and PCPU? I thought it resulted in some CPU id
> or other being reported back as -1, in much this manner.

yes, the existing tricky changes are mostly used to tackle this disconnection.

> 
> There's some tweaking of this stuff in e.g.
> xen_acpi_processor_get_power_info(). But equally
> xen_acpi_processor_get_info() has a bunch of cases for the != -1 case.
> 
> Does the dom0_vcpus_pin hypervisor option workaround this sort of thing?

We don't want to add that limitation to have dom0 vcpu number same as 
physical cpu number to use PM features. But yes Carsten can try use
same number to see whether it works for him. If it works, then there's other
corner cases we didn't capture. But since this works on his Intel box, which
I guess same configuration is used, I'd think it may come from some oddity
in AMD box's ACPI table which is not well handled by either common ACPI
code or Xen specific stubs.

Thanks
Kevin

> 
> This changeset refers to the -1 too:
> 
> commit 68320323a51c2378aca433c76157d9e66104ff1e
> Author: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>
> Date:   Tue Sep 14 14:41:52 2010 -0700
> 
>     xen/acpi: Add cpu hotplug support
> 
>     Add physical CPU hotplug support to origin/xen/next-2.6.32 branch.
>     Please notice that, even with this change, the acpi_processor->id is
>     still always -1. This is because several workaround in PM side depends
>     on acpi_processor->id == -1. As the CPU hotplug logic does not depends
>     on acpi_processor->id, I'd still keep it no changes.
> 
>     But we need change the acpi_processor->id in the future.
> 
>     Signed-off-by: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>
>     Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> 
> Ian.
> 
> > > Any help is welcome, but I will analyze further...
> >
> > Current Dom0 depends on several Xen specific functions like
> xen_acpi_get_power_info
> > you mentioned earlier, which is a copy from native acpi_get_power_info with
> xen
> > specific tweaks added. there's possibility that in your environment general
> ACPI code
> > is changed which is not reflected in Xen specific versions.
> >
> > Thanks
> > Kevin
> >
> > >
> > > Carsten.
> > >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Carsten Schiers
> > > Gesendet: Montag, 13. Juni 2011 15:22
> > > An: ke.yu; kevin.tian
> > > Cc: xen-devel
> > > Betreff: AW: RE: RE: RE: RE: RE: [Xen-devel] No C-States any longer...
> > >
> > > >>I will try to boot native Linux in order to verify 100%
> > > >> that the tables
> > > >> are there.
> > > >
> > > >yes, that's interesting data to compare.
> > >
> > > I have booted with a Live Linux and dumped acpi tables. Those are 100%
> > > identical with those
> > > I received from Dom0. I will now start looking into
> > > acpi_processor_get_power_info_fadt And
> > > check, why it is returning -ENODEV.
> > >
> > > Carsten.
> > >
> > >
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > > http://lists.xensource.com/xen-devel
> > >
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
> 


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