On Tue, Apr 26, 2016 at 02:53:54PM +0100, Will Deacon wrote: [...]
> > > > That sounds like a good compromise. > > > > So I could do the following: > > > > 1) In the uncore setup check for CONFIG_NUMA, if set use the NUMA > > information to determine the device node > > > > 2) If CONFIG_NUMA is not set we check if we run on a socketed system > > > > a) In that case we return an error and give a message that CONFIG_NUMA > > needs > > to be enabled > > b) Otherwise we have a single node system and use node_id = 0 > > That sounds sensible to me. How do you "check if we run on a socketed > system"? My assumption would be that you could figure this out from the > firmware tables? There are probably multiple ways to detect a socketed system, with some quite hardware specific. I would like to avoid parsing DT (and ACPI) though, if possible. A generic approach would be to do a query of the multiprocessor affinity register (MPIDR_EL1) on all CPUs. The AFF2 part (bits 23:16) contains the socket number on ThunderX. If this is non-zero on any CPU I would assume a socketed system. Would that be feasible? thanks, Jan
