Re: [PATCH] Documentation, dt, numa: Add note to empty NUMA node

[Gavin Shan]

On 6/24/21 3:37 PM, Randy Dunlap wrote:
> On 6/23/21 9:58 PM, Gavin Shan wrote:
> > On 6/24/21 12:14 PM, Randy Dunlap wrote:
> > > On 6/23/21 8:37 PM, Gavin Shan wrote:
> > > > The empty NUMA nodes, where no memory resides in, are allowed. For
> > > > these empty NUMA nodes, the 'len' of 'reg' property is zero. These
> > > > empty NUMA node IDs are still valid and parsed. I finds difficulty
> > > > to get where it's properly documented.
> > > >
> > > > So lets add note to empty NUMA nodes in the NUMA binding doc.
> > > >
> > > > Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
> > > > ---
> > > >    Documentation/devicetree/bindings/numa.txt | 4 ++++
> > > >    1 file changed, 4 insertions(+)
> > > >
> > > > diff --git a/Documentation/devicetree/bindings/numa.txt b/Documentation/devicetree/bindings/numa.txt
> > > > index 21b35053ca5a..c564705c0eac 100644
> > > > --- a/Documentation/devicetree/bindings/numa.txt
> > > > +++ b/Documentation/devicetree/bindings/numa.txt
> > > > @@ -109,6 +109,10 @@ Example:
> > > >    Dual socket system consists of 2 boards connected through ccn bus and
> > > >    each board having one socket/soc of 8 cpus, memory and pci bus.
> > > >    +Note that the empty NUMA nodes, which no memory resides in, are allowed
> > >
> > > Missing period at end of the sentence above.
> >
> > Oh, Yes. Thanks, Randy. I will replace "resides in" with "resides in period"
> > in v2.
>
> Cute. Would it help if I replaced "period" with Missing "full stop" or '.' at the end
> of the sentence?

Ah, yes, '.' is needed either. Do you want me to post a new revision or you
modify it right away? I don't know how device-tree patches get merged :)

> > > > +Their NUMA node IDs are still valid so that memory can be added into these
> > > > +NUMA nodes through hotplug afterwards.
> > > > +
> > > >        memory@c00000 {
> > > >            device_type = "memory";
> > > >            reg = <0x0 0xc00000 0x0 0x80000000>;
> >
> > By the way, I have one more question to check with you if I can. I'm not sure
> > if dummy and invalid 'unit-address' is allowed in the empty memory node name,
> > which follows the format "memory@unit-address'.
> >
> > (1) The 'unit-address' is same thing as to 'base address' for memory node,
> >      as specified in device-tree specification. I'm not sure if 'base address'
> >      can be dummy and invalid one since empty memory node doesn't have memory
> >      at all.
> >
> >      https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#node-names
> >
> > (2) I don't find the 'unit-address' is used in linux, but I'm not sure other
> >      software component like firmware uses it or not.
>
> I have no idea about that.
Okey.

Thanks,
Gavin