Re: [Qemu-devel] [PATCH v2 06/11] nvdimm acpi: initialize the resource used by NVDIMM ACPI

[Michael S. Tsirkin]

On Mon, Feb 15, 2016 at 10:11:05AM +0100, Igor Mammedov wrote:
> On Sun, 14 Feb 2016 13:57:27 +0800
> Xiao Guangrong <address@hidden> wrote:
> 
> > On 02/08/2016 07:03 PM, Igor Mammedov wrote:
> > > On Wed, 13 Jan 2016 02:50:05 +0800
> > > Xiao Guangrong <address@hidden> wrote:
> > >  
> > >> 32 bits IO port starting from 0x0a18 in guest is reserved for NVDIMM
> > >> ACPI emulation. The table, NVDIMM_DSM_MEM_FILE, will be patched into
> > >> NVDIMM ACPI binary code
> > >>
> > >> OSPM uses this port to tell QEMU the final address of the DSM memory
> > >> and notify QEMU to emulate the DSM method  
> > > Would you need to pass control to QEMU if each NVDIMM had its whole
> > > label area MemoryRegion mapped right after its storage MemoryRegion?
> > >  
> > 
> > No, label data is not mapped into guest's address space and it only
> > can be accessed by DSM method indirectly.
> Yep, per spec label data should be accessed via _DSM but question
> wasn't about it,
> Why would one map only 4Kb window and serialize label data
> via it if it could be mapped as whole, that way _DMS method will be
> much less complicated and there won't be need to add/support a protocol
> for its serialization.
>  

Is it ever accessed on data path? If not I prefer the current approach:
limit the window used, the serialization protocol seems rather simple.

-- 
MST