On Mon, Apr 9, 2018 at 1:38 PM, Oliver <ooh...@gmail.com> wrote: > On Mon, Apr 9, 2018 at 1:16 PM, Stephen Rothwell <s...@canb.auug.org.au> > wrote: >> Hi Dan, >> >> After merging the nvdimm tree, today's linux-next build (x86_64 >> allmodconfig) failed like this: >> >> ERROR: "of_node_to_nid" [drivers/nvdimm/of_pmem.ko] undefined! >> >> Caused by commit >> >> 717197608952 ("libnvdimm: Add device-tree based driver") >> >> X86 seems to not have a version of of_node_to_nid() even though CONFIG_OF >> and CONFIG_NUMA are both 'y' in this build. > > It's a side effect of a driver selecting CONFIG_OF accidently. There's > a patch to fix this in the drm-misc-next tree: > > https://lkml.org/lkml/2018/4/3/17 > >> I have used the nvdimm tree from next-20180406 for today. > > That works too.
Hmm, on closer inspection this is actually a bug in the of driver. The patch above fixes the specific problem that we hit on ia64 due to CONFIG_OF being selected by accident, but the underlying issue will affect any platform that doesn't provide an implementation of of_node_to_nid(). The fundamental problem is that the various actual implementations of of_node_to_nid (ppc, sparc and the generic one in of_numa.c) export the symbol. While the fallback implementation does not because it is defined as a weak symbol. As a result we'll get this build failure iff there's a call to of_node_to_nid() in a module. The one-line fix is just to delete the call to of_node_to_nid() in of_pmem.c. I have a patch that adds a Kconfig options and removes the weak symbol games. That needs Acks from the ppc, sparc and DT maintainers though so it'll take longer to organise. Oliver