On Mon, Jun 03, 2019 at 01:49:13AM -0700, Atish Patra wrote: > On 5/30/19 1:55 PM, Jeremy Linton wrote: > > Hi, > > > > On 5/29/19 4:13 PM, Atish Patra wrote: > > > cpu-map binding can be used to described cpu topology for both > > > RISC-V & ARM. It makes more sense to move the binding to document > > > to a common place. > > > > > > The relevant discussion can be found here. > > > https://lkml.org/lkml/2018/11/6/19 > > > > > > Signed-off-by: Atish Patra <atish.patra@xxxxxxx> > > > Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx> > > > Reviewed-by: Rob Herring <robh@xxxxxxxxxx> > > > --- > > > .../topology.txt => cpu/cpu-topology.txt} | 82 +++++++++++++++---- > > > 1 file changed, 66 insertions(+), 16 deletions(-) > > > rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (86%) > > > [...] > > <nit picking> > > > > While socket is optional, its probably a good idea to include the node > > in the example even if the result is the same. > > Sure. I will update that. > > That is because at least > > on arm64 the DT clusters=sockets decision had performance implications > > for larger systems. > > > > Assuring the socket information is correct is helpful by itself to avoid > > having to explain why a single socket machine is displaying some other > > value in lscpu. > > > Just for my understanding, can you give a example? > That's simple. Today any ARM{32,64} DT based platform sets their cluster id to physical package id, which is exposed to userspace. The userspace can/must interpret that as multi-socket system. E.g. TC2/Juno which 2 clusters show up as 2 socket systems which is wrong and needs fixing. We have fixed it for ARM64 ACPI based systems but for DT(mostly used in mobile/embedded) we need to make sure we don't break anything else before we fix it. -- Regards, Sudeep
