On Sun, Sep 09, 2018 at 07:04:25PM +0200, Benjamin Herrenschmidt wrote: > On Fri, 2018-08-31 at 14:58 +1000, Benjamin Herrenschmidt wrote: > > > > > A long shot, but something to consider, is that I failed to cover the > > > cases of dynamic devicetree updates (removing nodes that contain a > > > phandle) in ways other than overlays. Michael Ellerman has reported > > > such a problem for powerpc/mobility with of_detach_node(). A patch to > > > fix that is one of the tasks I need to complete. > > > > The only thing I can think of is booting via the BootX bootloader on > > those ancient macs results in a DT with no phandles. I didn't see an > > obvious reason why that would cause that patch to break though. > > Guys, we still don't have a fix for this one on its way upstream... > > My test patch just creates phandle properties for all nodes, that was > not intended as a fix, more a way to check if the problem was related > to the lack of phandles. > > I don't actually know why the new code causes things to fail when > phandles are absent. This needs to be looked at. > > I'm travelling at the moment and generally caught up with other things, > I haven't had a chance to dig, so just a heads up. I don't intend to > submit my patch since it's just a band aid. We need to figure out what > the actual problem is. Can you try this patch (w/o Ben's patch). I think the problem is if there are no phandles, then roundup_pow_of_two is passed 0 which is documented as undefined result. Though, if a DT has no properties with phandles, then why are we doing a lookup in the first place? 8<---------------------------------------------------------------------- diff --git a/drivers/of/base.c b/drivers/of/base.c index 9095b8290150..74eaedd5b860 100644 --- a/drivers/of/base.c +++ b/drivers/of/base.c @@ -140,6 +140,9 @@ void of_populate_phandle_cache(void) if (np->phandle && np->phandle != OF_PHANDLE_ILLEGAL) phandles++; + if (!phandles) + goto out; + cache_entries = roundup_pow_of_two(phandles); phandle_cache_mask = cache_entries - 1;
