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

[Gavin Shan <gshan@redhat.com>]

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@redhat.com>
>>>> ---
>>>>    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