Re: [Xen-devel] Xen, MCFG acpi table and E820 address map

[Santosh Jodh <Santosh.Jodh@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: Thursday, September 05, 2013 12:48 AM
> To: Santosh Jodh
> Cc: Gordan Bobic; David Vrabel; xen-devel; BorisOstrovsky; Konrad Rzeszutek
> Wilk
> Subject: RE: [Xen-devel] Xen, MCFG acpi table and E820 address map
> 
> >>> On 04.09.13 at 18:26, Santosh Jodh <Santosh.Jodh@xxxxxxxxxx> wrote:
> 
> >
> > -----Original Message-----
> > From: Gordan Bobic [mailto:gordan@xxxxxxxxxx]
> > Sent: Wednesday, September 04, 2013 9:24 AM
> > To: Santosh Jodh
> > Cc: Konrad Rzeszutek Wilk; Jan Beulich; xen-devel; Boris Ostrovsky;
> > David Vrabel
> > Subject: Re: [Xen-devel] Xen, MCFG acpi table and E820 address map
> >
> >  On Wed, 4 Sep 2013 16:14:55 +0000, Santosh Jodh
> > <Santosh.Jodh@xxxxxxxxxx>
> > wrote:
> >> -----Original Message-----
> >> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx]
> >> Sent: Wednesday, September 04, 2013 8:01 AM
> >> To: Jan Beulich
> >> Cc: Santosh Jodh; David Vrabel; xen-devel; Boris Ostrovsky
> >> Subject: Re: [Xen-devel] Xen, MCFG acpi table and E820 address map
> >>
> >> On Wed, Sep 04, 2013 at 10:16:26AM +0100, Jan Beulich wrote:
> >>> >>> On 04.09.13 at 03:13, Santosh Jodh <Santosh.Jodh@xxxxxxxxxx>
> >>> wrote:
> >>> > Xen will use information from MCFG acpi table to access PCIe
> >>> > extended configuration space. However, Xen validates MCFG table by
> >>> > making sure that the addresses specified in the MCFG table is
> >>> > correctly marked as reserved in the E820 address map. If it is
> >>> not,
> >>> > the MCFG table is ignored - thereby preventing Xen from accessing
> >>> PCIe extended configuration space.
> >>> >
> >>> > I recently came across a workstation class system that supports
> >>> > VT-d. This system BIOS has a valid MCFG table. The BIOS does NOT
> >>> > report the MCFG addresses as reserved in the E820 address map.
> >>> > However, the addresses ARE claimed as reserved via the ACPI
> >>> > motherboard resource devnode (PNP0C01) mechanism.
> >>
> >> Could you tell me what machine this is? It would be good to know to
> >> develop a patch against it.
> >> [Santosh Jodh] Unfortunately, this is a new platform I cannot
> >> disclose much about.
> >
> >  If this is pre-release/experimental hardware, isn't the  right thing
> > to do to talk to the manufacturer and get them  to fix the BIOS so it
> > exposes the correct e820 map in the  first place?
> > [Santosh Jodh] yes - BIOS fix is in progress. My original query was -
> > is this an exception? If it is a trend, then Xen should handle this better.
> 
> You seem to ignore my earlier response: Xen _does_ handle this. It's the pv-
> ops kernel that doesn't make use of the interface the hypervisor provides.
[Santosh Jodh] I was not trying ignore your response, sorry if it came across 
like that. I was simply trying to explain reason for my original email. It's 
great to know Xen already handles this and look forward to dom0 fix going in as 
well.

> 
> And a remark to your mail response style - please try to set up your mail
> client such that it properly quotes the original text. The way you did your
> responses on this thread so far makes it pretty hard to spot your additions
> without first re-reading most of what was already said.
[Santosh Jodh] Does this work better?

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