Memory hotplug can fail when upcoming, yet-to-be-upstreamed, 2.7 feature DDW is enabled. This happens due to a guest kernel bug which results in DDW code in QEMU obtaining incorrect value of max possible memory address. This incorrect max mem value results in incorrect DDW size which later causes hotplug to fail.
While guest fix has been proposed, this patchset works around the problem within QEMU. The workaround is described in patch 3/3. In summary this patchset changes the alignment gap b/n RAM and hotplug region for pseries-2.7 onwards so that memory hotplug works with buggy guests when DDW is present from 2.7 onwards. v0: https://lists.nongnu.org/archive/html/qemu-ppc/2016-04/msg00226.html Bharata B Rao (3): spapr: Introduce pseries-2.7 machine type spapr: Remove alignment gap b/n RAM and hotplug regions spapr: spapr: Work around the memory hotplug failure with DDW hw/ppc/spapr.c | 92 +++++++++++++++++++++++++++++++++++++++----------- include/hw/ppc/spapr.h | 10 +++--- 2 files changed, 77 insertions(+), 25 deletions(-) -- 2.1.0
