Re: [Qemu-devel] [PATCH v2 3/8] nvdimm acpi: introduce _FIT

[Igor Mammedov]

On Mon, 10 Oct 2016 21:09:30 +0800
Xiao Guangrong <address@hidden> wrote:

> On 10/10/2016 08:51 PM, Igor Mammedov wrote:
> > On Sat, 8 Oct 2016 15:17:14 +0800
> > Xiao Guangrong <address@hidden> wrote:
> >  
> >> On 09/30/2016 09:14 PM, Igor Mammedov wrote:  
> >>> On Fri, 12 Aug 2016 14:54:05 +0800
> >>> Xiao Guangrong <address@hidden> wrote:
> >>>  
> >>>> _FIT is required for hotplug support, guest will inquire the updated
> >>>> device info from it if a hotplug event is received
> >>>>
> >>>> As FIT buffer is not completely mapped into guest address space, so a
> >>>> new function, Read FIT whose function index is 0xFFFFFFFF, is reserved
> >>>> by QEMU to read the piece of FIT buffer. The buffer is concatenated
> >>>> before _FIT return  
> >>> Only issuer of UUID 2F10E7A4-9E91-11E4-89D3-123B93F75CBA can reserve
> >>> 0xFFFFFFFF for some purposes.
> >>> So spec should be amended first or custom generated UUID should be used.  
> >>
> >> Okay.
> >>
> >> I will change the changelog to reflect this fact and move the spec update
> >> to this patch.  
> > under spec, I've meant ACPI spec where this UUID is declared  
> 
> Er. ACPI spec just said that "0xFFFF is reserved", not sure it will be used
> in the future.
> 
> I'd prefer to custom-generated UUID, however, currently the UUID is checked
> in OSPM, i.e, QEMU is not able to distinguish other UUIDs,
I'd go with custom-generated UUID

> so how about
> drop the UUID check in ACPI and pass the UUID info to QEMU?
It's a bit late to do so as it would be qemu-guest ABI change and
one would need to maintain old and new protocol.