Re: [Xen-devel] [PATCH v2 4/4] tools/libacpi: announce that PVHv2 has no CMOS RTC in FADT

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On Fri, Dec 02, 2016 at 10:20:59AM -0700, Jan Beulich wrote:
> >>> On 02.12.16 at 14:48, <roger.pau@xxxxxxxxxx> wrote:
> > @@ -436,7 +439,7 @@ struct acpi_20_slit {
> >   * Table revision numbers.
> >   */
> >  #define ACPI_2_0_RSDP_REVISION 0x02
> > -#define ACPI_2_0_FADT_REVISION 0x04
> > +#define ACPI_2_0_FADT_REVISION 0x05
> 
> Do we really want to make this change unconditionally, rather than
> only for PVH guests? I'm not sure which (older) OSes look at table
> revisions (and may hence end up being incompatible), or whether
> OSes may expect certain table versions together with certain base
> ACPI versions. I think I had pointed out before that we really
> should have the guest config file "acpi=" setting mean a version
> number, and table revisions should then be selected according to
> that base version. As that's a larger change, simply using one
> fixed version for HVM and another for PVH would look fine to me.

I don't mind using different revision numbers for HVM and PVH, but that means 
that we would need to also have two different structures, one for FADT 4.0 and 
one for FADT 5.0, which is kind of redundant, or maybe play tricks with size 
and the checksum. Also the current FADT table strcuture is named acpi_20_fadt, 
which seems to have gotten out-of-sync with the version we are using (4).

Roger.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel