• David Gibson's avatar
    powerpc/pseries: Advertise HPT resizing support via CAS · 0de0fb09
    David Gibson authored
    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. We use bit 5 of byte 6 of
    option vector 5 for this purpose, as defined in the PAPR ACR "HPT
    resizing option".
    Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
    Reviewed-by: default avatarAnshuman Khandual <khandual@linux.vnet.ibm.com>
    Reviewed-by: default avatarPaul Mackerras <paulus@samba.org>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    0de0fb09
prom_init.c 80.6 KB