Re: [Xen-devel] [PATCH 1/6] docs: update docs for the ~/platform/generation-id key

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-05-28 at 15:51 +0100, Andrew Cooper wrote:
> On 28/05/14 15:44, Ian Campbell wrote:
> > On Tue, 2014-05-27 at 18:31 +0100, David Vrabel wrote:
> >> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
> >> ---
> >>  docs/misc/xenstore-paths.markdown |   24 ++++++++++++++++--------
> >>  1 file changed, 16 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/docs/misc/xenstore-paths.markdown 
> >> b/docs/misc/xenstore-paths.markdown
> >> index 70ab7f4..41d7d6d 100644
> >> --- a/docs/misc/xenstore-paths.markdown
> >> +++ b/docs/misc/xenstore-paths.markdown
> >> @@ -166,11 +166,6 @@ use the xenstore-based protocol instead (see 
> >> ~/control/shutdown,
> >>  below) even if the guest has advertised support for the event channel
> >>  protocol.
> >>  
> >> -#### ~/hvmloader/generation-id-address = ADDRESS [r,HVM,INTERNAL]
> >> -
> >> -The hexadecimal representation of the address of the domain's
> >> -"generation id".
> >> -
> >>  #### ~/hvmloader/allow-memory-relocate = ("1"|"0") [HVM,INTERNAL]
> >>  
> >>  If the default low MMIO hole (below 4GiB) is not big enough for all
> >> @@ -193,9 +188,22 @@ Various platform properties.
> >>  
> >>  #### ~/platform/generation-id = INTEGER ":" INTEGER [HVM,INTERNAL]
> >>  
> >> -Two 64 bit values that represent the Windows Generation ID.
> >> -Is used by the BIOS initializer to get this value.
> >> -If not present or "0:0" (all zeroes) device will not be present to the 
> >> machine.
> >> +The upper and lower 64-bit words of the 128-bit VM Generation ID.
> >> +
> >> +This key is used by hvmloader to create the ACPI VM Generation ID
> >> +device.  It initialises a 16 octet region of guest memory with this
> >> +value.  The guest physical address of this region is saved in the
> >> +HVM_PARAM_VM_GENERATION_ID_ADDR HVM parameter.
> >> +
> >> +If this key is not present, is empty, or is all-zeros ("0:0") then the
> >> +ACPI device is not created.
> >> +
> >> +The toolstack should, before unpausing a created or restored HVM
> >> +domain, set this key and write the same ID to the guest memory
> >> +location in HVM_PARAM_VM_GENERATION_ID_ADDR (if this address is
> >> +non-zero).
> > Is the toolstack or hvmloader now responsible for writing this value to
> > guest memory? It seems like it might be a shared responsibility via some
> > mode of cooperation that I'm not following?
> >
> > Ian.
> 
> HVMLoader is responsible for allocating the space inside the guest to
> start with, and for populating it with the initial value.
> 
> However, HVMLoader is *not* rerun on suspend/resume, so something
> external in the toolstack needs to be able to update the value when needed.

The new docs say "before unpausing a created", which is misleading then.

Ian.



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