spapr: Support ibm, lrdr-capacity device tree property

Add support for ibm,lrdr-capacity since this is needed by the guest
kernel to know about the possible hot-pluggable CPUs and Memory. With
this, pseries kernels will start reporting correct maxcpus in
/sys/devices/system/cpu/possible.

Also define the minimum hotpluggable memory size as 256MB.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
[agraf: Fix compile error on 32bit hosts]
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 18 insertions, 0 deletions

diff --git a/docs/specs/ppc-spapr-hotplug.txt b/docs/specs/ppc-spapr-hotplug.txt
index d35771cc2b..46e07196bb 100644
--- a/docs/specs/ppc-spapr-hotplug.txt
+++ b/docs/specs/ppc-spapr-hotplug.txt
@@ -284,4 +284,22 @@ struct rtas_event_log_v6_hp {
     } drc;
 } QEMU_PACKED;
 
+== ibm,lrdr-capacity ==
+
+ibm,lrdr-capacity is a property in the /rtas device tree node that identifies
+the dynamic reconfiguration capabilities of the guest. It consists of a triple
+consisting of <phys>, <size> and <maxcpus>.
+
+  <phys>, encoded in BE format represents the maximum address in bytes and
+  hence the maximum memory that can be allocated to the guest.
+
+  <size>, encoded in BE format represents the size increments in which
+  memory can be hot-plugged to the guest.
+
+  <maxcpus>, a BE-encoded integer, represents the maximum number of
+  processors that the guest can have.
+
+pseries guests use this property to note the maximum allowed CPUs for the
+guest.
+
 [1] http://thread.gmane.org/gmane.linux.ports.ppc.embedded/75350/focus=106867