Re: [Qemu-devel] [PATCH] acpi/nvdimm: remove forward name references

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 25 Apr 2018 17:17:04 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> On Wed, Apr 25, 2018 at 03:49:38PM +0200, Igor Mammedov wrote:
> > On Tue, 24 Apr 2018 21:06:37 +0300
> > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> >   
> > > On Tue, Apr 24, 2018 at 05:47:58PM +0000, Schmauss, Erik wrote:  
> > > > 
> > > >     
> > > > > -----Original Message-----
> > > > > From: Michael S. Tsirkin [mailto:mst@redhat.com]
> > > > > Sent: Tuesday, April 24, 2018 10:43 AM
> > > > > To: Igor Mammedov <imammedo@redhat.com>
> > > > > Cc: Schmauss, Erik <erik.schmauss@intel.com>; qemu-devel@nongnu.org; Xiao
> > > > > Guangrong <xiaoguangrong.eric@gmail.com>; Williams, Dan J
> > > > > <dan.j.williams@intel.com>
> > > > > Subject: Re: [PATCH] acpi/nvdimm: remove forward name references
> > > > > 
> > > > > On Tue, Apr 24, 2018 at 09:57:22AM +0200, Igor Mammedov wrote:    
> > > > > > On Tue, 24 Apr 2018 04:02:40 +0300
> > > > > > "Michael S. Tsirkin" <mst@redhat.com> wrote:
> > > > > > 
[...]
> > > > > > From spec
> > > > > >  DefOpRegion := OpRegionOp NameString RegionSpace RegionOffset
> > > > > > RegionLen  RegionOffset := TermArg => Integer  TermArg := Type2Opcode
> > > > > > | DataObject | ArgObj | LocalObj
> > > > > >
> > > > > > So named object is not accepted,    
> > > > > 
> > > > > might be worth checking what happens with actual OSPMs.
> > > > > If it does happen to work, we can try tweaking the ACPI spec to allow this.    
> > > > 
> > > > I'm looking at the ACPI6.2a spec on page 840 and it says
> > > > TermArg := Type2Opcode | DataObject | Argterm |LocalTerm |NameString |SymbolicExpression    
> > > 
> > > Oh right, that's there since ACPI 6.0.  
> > Strange, I've rechecked AML definition of TermArg in 6.0 and 6.2a
> > and it still says only
> > 
> >   TermArg := Type2Opcode | DataObject | ArgObj | LocalObj
> > 
> > For 6.2a, I'm looking at chapter "20.2.5 Term Objects Encoding"
> > where exactly do you guys see that longer variant?  
> 
> Oh interesting. That's in
> 19.2.3 ASL Root and Secondary Terms
> 
> How come it's not the same?
bugs are everywhere, see "20.2.5 Term Objects Encoding"

> 
> >   
> > > As usual, the issue is that
> > > we can't easily check what does OSPM support.
> > > This is really something worth fixing in the spec IMHO.
> > > We could just try and test a bunch of guest OSPMs and if
> > > they happen to work, switch to that. Lots of work for
> > > uncertain benefit.  
> > I think some windows versions weren't happy with it when
> > we were trying to use dynamic operation regions with offset
> > as namestring.  
> 
> 
> Good to know, thanks.
I'll try to retest MS VMs I have here, to see which one breaks.