Re: [Xen-devel] [PATCH] Add code to track the address of the VM generation id buffer across a

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

Would the following be sufficient?

  Paul

diff -r 62ff6a318c5d docs/man/xl.cfg.pod.5
--- a/docs/man/xl.cfg.pod.5     Wed Nov 30 16:59:58 2011 -0800
+++ b/docs/man/xl.cfg.pod.5     Thu Dec 01 11:52:58 2011 +0000
@@ -484,6 +484,12 @@ of Xen) within a Xen guest or to support
 which uses hardware virtualisation extensions (e.g. Windows XP
 compatibility mode on more modern Windows OS).

+=item B<generation_id=NUMBER>
+
+This value will be exposed inside the guest at an address which
+can be determined by evaluating the ADDR package of an ACPI device
+with _CID "VM_Gen_Counter".
+
 =back

 =head3 Guest Virtual Time Controls
diff -r 62ff6a318c5d tools/firmware/hvmloader/acpi/dsdt.asl
--- a/tools/firmware/hvmloader/acpi/dsdt.asl    Wed Nov 30 16:59:58 2011 -0800
+++ b/tools/firmware/hvmloader/acpi/dsdt.asl    Thu Dec 01 11:52:58 2011 +0000
@@ -398,6 +398,25 @@ DefinitionBlock ("DSDT.aml", "DSDT", 2,
                     })
                 }

+                /* VM Generation ID Device
+                 *
+                 * The basic requirements of this device are as follows:
+                 *
+                 * - It must be exposed somewhere in ACPI namespace with a 
_CID of
+                 *   "VM_Gen_Counter".
+                 * - It must also include a _DDN of "VM_Gen_Counter".
+                 * - It must contain a _HID object but no particular value is
+                 *   required.
+                 * - It must expose a package called ADDR which evaluates to 
two
+                 *   integers; the first being the low order 32-bits of a guest
+                 *   physical address (GPA), the second by the high order 
32-bits of
+                 *   the GPA. This GPA is the address of an 8-byte aligned 
8-byte
+                 *   buffer containing the VM generation ID.
+                 *   This buffer must not be in ranges supported as 
AddressRangeMemory
+                 *   or AddressRangeACPI and must not be mapped by any PTE 
with caching
+                 *   disabled. (See the code in 
tools/firmware/hvmloader/acpi/build.c
+                 *   which determines the address and contents of the buffer).
+                 */
                 Device(VGID) {
                     Name(_HID, EisaID ("PNP0A06"))
                     Name(_UID, 0x00)

> -----Original Message-----
> From: Ian Campbell
> Sent: 01 December 2011 10:00
> To: Paul Durrant
> Cc: Konrad Rzeszutek Wilk; xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: RE: [Xen-devel] [PATCH] Add code to track the address of
> the VM generation id buffer across a
> 
> On Thu, 2011-12-01 at 09:47 +0000, Paul Durrant wrote:
> > > -----Original Message-----
> > > From: Ian Campbell
> > > Sent: 01 December 2011 08:59
> > > To: Paul Durrant
> > > Cc: Konrad Rzeszutek Wilk; xen-devel@xxxxxxxxxxxxxxxxxxx
> > > Subject: Re: [Xen-devel] [PATCH] Add code to track the address
> of
> > > the VM generation id buffer across a
> > >
> > > On Thu, 2011-12-01 at 08:46 +0000, Paul Durrant wrote:
> > > > Konrad,
> > > >
> > > >   Did you see my previous patch set? The introductory comment
> was:
> > >
> > >
> > > I think that description belongs somewhere permanent, either in
> > > docs/misc or as a comment in an appropriate header.
> > >
> >
> > Good point. Perhaps I should stick the comment just above the
> device description in the dsdt?
> 
> That would do I guess.
> 
> I guess more important would be the user facing toolstack specific
> semantics/documentation i.e. the manpage.
> 
> Ian.
> 

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