v3:
- use pc_machine_class_init() for default. (Eduardo)
- make 'gap' boolean and just add 1 byte gap
when calculating new_addr for DIMM.
v2:
make inter_dimm_gap a boolean and inster gap in 1 byte
instead of 2Mb, due to alignment that gap would be extended
up to natural backend alignment value.
it's a simplier way suggested by Michael S. Tsirkin
to workaround virtio bug reported earlier:
http://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg00522.html
where virtio can't handle buffer that crosses border
between 2 DIMM's (i.e. 2 MemoryRegions).
idea is to leave gaps between DIMMs, making their GPAs
non contiguous, which effectively forces kmalloc
to not use DIMM if buffer doesn't fit inside of it.
Simpler reproducer:
qemu-system-x86_64 -enable-kvm -m 256,slots=250,maxmem=32G -drive
if=virtio,file=/dev/slow/rhel72 \
`for i in $(seq 0 58); do echo -n "-object memory-backend-ram,id=m$i,size=10M
-device pc-dimm,id=dimm$i,memdev=m$i "; done` \
-nodefaults -snapshot -serial stdio -nographic -M pc-i440fx-2.4
if guest manages to boot just login and do:
dd if=/dev/vda of=/dev/null bs=128M
it will crash QEMU in 99% cases with following message:
qemu-system-x86_64: virtio: error trying to map MMIO memory
Tested vs master and mst/PCI trees.
Igor Mammedov (2):
memhp: extend address auto assignment to support gaps
pc: memhp: force gaps between DIMM's GPA
hw/i386/pc.c | 5 ++++-
hw/i386/pc_piix.c | 1 +
hw/i386/pc_q35.c | 1 +
hw/mem/pc-dimm.c | 15 +++++++++------
hw/ppc/spapr.c | 2 +-
include/hw/i386/pc.h | 1 +
include/hw/mem/pc-dimm.h | 7 ++++---
7 files changed, 21 insertions(+), 11 deletions(-)
--
1.8.3.1
