Re: [PATCH 05/14] cxl/mem: Register CXL memX devices

[David Rientjes]

On Mon, 1 Feb 2021, Ben Widawsky wrote:

> > > diff --git a/Documentation/ABI/testing/sysfs-bus-cxl b/Documentation/ABI/testing/sysfs-bus-cxl
> > > new file mode 100644
> > > index 000000000000..fe7b87eba988
> > > --- /dev/null
> > > +++ b/Documentation/ABI/testing/sysfs-bus-cxl
> > > @@ -0,0 +1,26 @@
> > > +What:		/sys/bus/cxl/devices/memX/firmware_version
> > > +Date:		December, 2020
> > > +KernelVersion:	v5.12
> > > +Contact:	linux-cxl@xxxxxxxxxxxxxxx
> > > +Description:
> > > +		(RO) "FW Revision" string as reported by the Identify
> > > +		Memory Device Output Payload in the CXL-2.0
> > > +		specification.
> > > +
> > > +What:		/sys/bus/cxl/devices/memX/ram/size
> > > +Date:		December, 2020
> > > +KernelVersion:	v5.12
> > > +Contact:	linux-cxl@xxxxxxxxxxxxxxx
> > > +Description:
> > > +		(RO) "Volatile Only Capacity" as reported by the
> > > +		Identify Memory Device Output Payload in the CXL-2.0
> > > +		specification.
> > > +
> > > +What:		/sys/bus/cxl/devices/memX/pmem/size
> > > +Date:		December, 2020
> > > +KernelVersion:	v5.12
> > > +Contact:	linux-cxl@xxxxxxxxxxxxxxx
> > > +Description:
> > > +		(RO) "Persistent Only Capacity" as reported by the
> > > +		Identify Memory Device Output Payload in the CXL-2.0
> > > +		specification.
> > 
> > Aren't volatile and persistent capacities expressed in multiples of 256MB?
> 
> As of the spec today, volatile and persistent capacities are required to be
> in multiples of 256MB, however, future specs may not have such a requirement and
> I think keeping sysfs ABI easily forward portable makes sense.
> 

Makes sense, can we add that these are expressed in bytes or is that 
already implied?