Re: [PATCH] drivers/of: Introduce ARCH_HAS_OWN_OF_NUMA

[Rob Herring]

On Mon, Apr 9, 2018 at 4:05 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
> On Mon, Apr 9, 2018 at 1:52 PM, Rob Herring <robh@xxxxxxxxxx> wrote:
>> On Mon, Apr 9, 2018 at 2:46 AM, Oliver O'Halloran <oohall@xxxxxxxxx> wrote:
>>> Some OF platforms (pseries and some SPARC systems) has their own
>>> implementations of NUMA affinity detection rather than using the generic
>>> OF_NUMA driver, which mainly exists for arm64. For other platforms one
>>> of two fallbacks provided by the base OF driver are used depending on
>>> CONFIG_NUMA.
>>>
>>> In the CONFIG_NUMA=n case the fallback is an inline function in of.h.
>>> In the =y case the fallback is a real function which is defined as a
>>> weak symbol so that it may be overwritten by the architecture if desired.
>>>
>>> The problem with this arrangement is that the real implementations all
>>> export of_node_to_nid(). Unfortunately it's not possible to export the
>>> fallback since it would clash with the non-weak version. As a result
>>> we get build failures when:
>>>
>>> a) CONFIG_NUMA=y && CONFIG_OF=y, and
>>> b) The platform doesn't implement of_node_to_nid(), and
>>> c) A module uses of_node_to_nid()
>>>
>>> Given b) will be true for most platforms this is fairly easy to hit
>>> and has been observed on ia64 and x86.
>>
>> How specifically do we hit this? The only module I see using
>> of_node_to_nid in mainline is Cell EDAC driver.
>
> The of_pmem driver is using it currently pending for a 4.17 pull
> request. Stephen hit the compile failure in -next.

You mean the stuff reviewed last week in the middle of the merge
window? Sounds like 4.18 material to me.

Rob