Messages in this thread Patch in this message | | | Subject | Re: [PATCH v4] Documentation, dt, numa: Add note to empty NUMA node | From | Gavin Shan <> | Date | Fri, 25 Jun 2021 18:36:48 +1000 |
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On 6/25/21 5:06 PM, Andrew Jones wrote: > On Fri, Jun 25, 2021 at 09:02:17AM +0200, Andrew Jones wrote: >> On Fri, Jun 25, 2021 at 01:23:38PM +0800, Gavin Shan wrote: >>> The empty memory nodes, where no memory resides in, are allowed. >>> For these empty memory nodes, the 'len' of 'reg' property is zero. >>> The NUMA node IDs are still valid and parsed, but memory can be >>> added to them through hotplug afterwards. I finds difficulty to >>> get where it's properly documented. >>> >>> So lets add note to empty memory 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..0fc882e44270 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 empty memory nodes, which no memory resides in, are allowed. >>> +The NUMA node IDs in these empty memory nodes are still valid, but >>> +memory can be added into them through hotplug afterwards. >> >> Please change the second sentence to: >> >> The NUMA node IDs in these empty memory nodes are still valid and >> memory may be added into them through hotplug afterwards. >> >> But, this doesn't look like the right place for this paragraph. You're >> adding the paragraph to the example section, but the example doesn't have >> any empty memory nodes. >> >> I think the paragraph should be added to section "2 - numa-node-id" and an > > Or maybe even create a new section for it. > >> example empty memory node should be provided. Also, the commit message >> talks about the length of 'reg' being zero, which is an important >> distinction which should also be documented. >>
Drew, thanks for your comments. Yeah, it sounds sensible to create a new section for it and an example would be more helpful. Please check if below changes are fine to you. I probably need Randy's review again.
I'm trying to avoid too many revisions for this sort of trivial patch, even though I already had. However, it's time frame for v5.14 and I'm pushing this to be merged during the cycle.
--- a/Documentation/devicetree/bindings/numa.txt +++ b/Documentation/devicetree/bindings/numa.txt @@ -103,7 +103,65 @@ Example: }; ============================================================================== -4 - Example dts +4 - Empty memory node +============================================================================== + +Empty memory nodes, which no memory resides in, are allowed. The 'length' +field of 'reg' property is zero, but 'base-address' is dummy and invalid +for these empty memory nodes. However, the NUMA node IDs and distance maps +for them are still valid, but memory may be added into them through hotplug +afterwards. + +Example: + + memory@0 { + device_type = "memory"; + reg = <0x0 0x0 0x0 0x80000000>; + numa-node-id = <0>; + }; + + memory@0x80000000 { + device_type = "memory"; + reg = <0x0 0x80000000 0x0 0x80000000>; + numa-node-id = <1>; + }; + + /* Empty memory node */ + memory@0x100000000 { + device_type = "memory"; + reg = <0x1 0x0 0x0 0x0>; + numa-node-id = <2>; + }; + + /* Empty memory node */ + memory@0x180000000 { + device_type = "memory"; + reg = <0x1 0x80000000 0x0 0x0>; + numa-node-id = <3>; + }; + + distance-map { + compatible = "numa-distance-map-v1"; + distance-matrix = <0 0 10>, + <0 1 20>, + <0 2 40>, + <0 3 20>, + <1 0 20>, + <1 1 10>, + <1 2 20>, + <1 3 40>, + <2 0 40>, + <2 1 20>, + <2 2 10>, + <2 3 20>, + <3 0 20>, + <3 1 40>, + <3 2 20>, + <3 3 10>; + }; + +============================================================================== +5 - Example dts ============================================================================== Dual socket system consists of 2 boards connected through ccn bus and
Thanks, Gavin
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