On 01/29/2016 10:54 AM, David Gibson wrote:

The hypervisor needs to know a guest is capable of using the HPT resizing
PAPR extension in order to make full advantage of it for memory hotplug.

If the hypervisor knows the guest is HPT resize aware, it can size the
initial HPT based on the initial guest RAM size, relying on the guest to
resize the HPT when more memory is hot-added.  Without this, the hypervisor
must size the HPT for the maximum possible guest RAM, which can lead to
a huge waste of space if the guest never actually expends to that maximum
size.

This patch advertises the guest's support for HPT resizing via the
ibm,client-architecture-support OF interface.  Obviously, the actual
encoding in the CAS vector is tentative until the extension is officially
incorporated into PAPR.  For now we use bit 0 of (previously unused) byte 8
of option vector 5.

Signed-off-by: David Gibson <redacted>

Reviewed-by: Anshuman Khandual <redacted>