Re: [PATCH 05/14] cxl/mem: Register CXL memX devices
From: Dan Williams
Date: Mon Feb 01 2021 - 16:56:24 EST
On Mon, Feb 1, 2021 at 1:53 PM David Rientjes <rientjes@xxxxxxxxxx> wrote:
>
> 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?
Makes sense to declare units here.