Re: [PATCH v4 4/4] ACPI: Add documentation for exposing MRRM data

Luck, Tony
2025-05-05T16:45:34Z

On Sun, May 04, 2025 at 11:34:51PM -0700, Fenghua Yu wrote:
> Hi, Tony,
>
> On 4/29/25 13:24, Tony Luck wrote:
> > Initial implementation provides enumeration of the address ranges
> > NUMA node numbers, and BIOS assigned region IDs for each range.
> >
> > Signed-off-by: Tony Luck <tony.luck@intel.com>
> > ---
> > Documentation/ABI/testing/sysfs-firmware-acpi | 21 +++++++++++++++++++
> > 1 file changed, 21 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-firmware-acpi b/Documentation/ABI/testing/sysfs-firmware-acpi
> > index 5249ad5a96d9..fffba38f9ce1 100644
> > --- a/Documentation/ABI/testing/sysfs-firmware-acpi
> > +++ b/Documentation/ABI/testing/sysfs-firmware-acpi
> > @@ -248,3 +248,24 @@ Description:
> > # cat ff_pwr_btn
> > 7 enabled
> > +What: /sys/firmware/acpi/memory_ranges/rangeX
> > +Date: February 2025
> > +Contact: Tony Luck <tony.luck@intel.com>
> > +Description:
> > + On systems with the ACPI MRRM table reports the
> > + parameters for each range.
>
> Is there a need to explain what's "X" here? The "X" is not a number directly
> reported by MRRM, right?
>
> Maybe something like "range ID is enumerated from MRRM starting from 0."?

I'm not sure about this one. "X" in the ABI documentation files is a
standard notation for "there are several of these with a number for
each". When the number does refer to some physical object, then there
may be a need to describe it. But if it is simply a counter to give a
separate name for each one of some repeating thing ... then I don't
think it helps to add additional explanation.

>
> > +
> > + base: Starting system physical address.
> > +
> > + length: Length of this range in bytes.
> > +
> > + node: NUMA node that this range belongs to. Negative numbers
> > + indicate that the node number could not be determined (e.g
> > + for an address range that is reserved for future hot add of
> > + memory).
> > +
> > + local_region_id: ID associated with access by agents
> > + local to this range of addresses.
> > +
> > + remote_region_id: ID associated with access by agents
> > + non-local to this range of addresses.
>
> Thanks.
>
> -Fenghua

-Tony