Re: [Qemu-devel] [PATCH] nvdimm acpi: fix region format interface code

[Haozhong Zhang]

On 06/08/17 14:40 +0800, Xiao Guangrong wrote:
> 
> 
> On 06/08/2017 01:06 PM, Haozhong Zhang wrote:
> > On 06/08/17 11:07 +0800, Xiao Guangrong wrote:
> > > 
> > > 
> > > On 06/07/2017 04:06 PM, Haozhong Zhang wrote:
> > > > Per ACPI 6.2, section 5.2.25.6 and JEDEC Annex L Release 3, the
> > > > current region format interface code 0x201 indicates the block
> > > > addressed function interface 1, rather than a byte addressable
> > > > interface. Fix it by using 0x301 which indicates the byte addressable
> > > > no energy backed function interface 1.
> > > > 
> > > > Signed-off-by: Haozhong Zhang <address@hidden>
> > > > ---
> > > >    hw/acpi/nvdimm.c | 7 ++++---
> > > >    1 file changed, 4 insertions(+), 3 deletions(-)
> > > > 
> > > > diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
> > > > index 8e7d6ec034..b5734f5897 100644
> > > > --- a/hw/acpi/nvdimm.c
> > > > +++ b/hw/acpi/nvdimm.c
> > > > @@ -338,9 +338,10 @@ static void nvdimm_build_structure_dcr(GArray 
> > > > *structures, DeviceState *dev)
> > > >        nfit_dcr->revision_id = cpu_to_le16(1 /* Current Revision 
> > > > supported
> > > >                                                 in ACPI 6.0 is 1. */);
> > > >        nfit_dcr->serial_number = cpu_to_le32(sn);
> > > > -    nfit_dcr->fic = cpu_to_le16(0x201 /* Format Interface Code. See 
> > > > Chapter
> > > > -                                         2: NVDIMM Device Specific 
> > > > Method
> > > > -                                         (DSM) in DSM Spec Rev1.*/);
> > > > +    nfit_dcr->fic = cpu_to_le16(0x301 /* Format Interface Code:
> > > > +                                         Byte addressable, no energy 
> > > > backed.
> > > > +                                         See ACPI 6.2, sect 5.2.25.6 
> > > > and
> > > > +                                         JEDEC Annex L Release 3. */);
> > > 
> > > Shouldn't the 'no energy backend' indicator be set only for !dax disk?
> > 
> > Above specs define RFIC for two classes of byte-addressable NVDIMM:
> > 1. 0x10[0|1]: A function containing byte addressable persistent memory
> >                whose persistence is achieved through the use of DRAM,
> >                nonvolatile memory (e.g., Flash) and an energy source.
> >           Only the DRAM portion is addressable by the system.
> > 2. 0x30[0|1]: A function containing byte addressable persistent
> >                memory. All of the persistent memory is addressable by
> >                the system. No external energy source is required.
> > If the last bit is 0, then it's a proprietary interface.
> 
> As both of them indicate persistent memory, it is okay to me.
> 
> The FIC, 0x201, comes from the document of Intel DSM example, i have no idea 
> why
> it uses 0x201. Maybe it is worth being fixed too.
> 

I guess the reason is it's an example, e.g. "... describes an
*example* _DSM interface for NVDIMM Device with Region Format
Interface Code (RFIC) of 0x0201" at the beginning of Chapter 2.

Haozhong