if DIMMs with different size/alignment are interleaved
in creation order, it could lead to hotplug-memory
container fragmentation and following inability to use
all RAM upto maxmem.
For example:
-m 4G,slots=3,maxmem=7G
-object memory-backend-file,id=mem-1,size=256M,mem-path=/pagesize-2MB
-device pc-dimm,id=mem1,memdev=mem-1
-object memory-backend-file,id=mem-2,size=1G,mem-path=/pagesize-1GB
-device pc-dimm,id=mem2,memdev=mem-2
-object memory-backend-file,id=mem-3,size=256M,mem-path=/pagesize-2MB
-device pc-dimm,id=mem3,memdev=mem-3
fragments hotplug-memory container and doesn't allow
to use 1GB hugepage backend to consume remainig 1Gb.
To ease managment factor count in max 1Gb alignment for
each memory slot when sizing hotplug-memory region so
that regadless of fragmentaion it would be possible to
add max aligned DIMM.
Signed-off-by: Igor Mammedov <imamm...@redhat.com>
---
v2:
spelling fixes in commit message
---
hw/i386/pc.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 4c62ba7..6dccb16 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1277,6 +1277,11 @@ FWCfgState *pc_memory_init(MachineState *machine,
pcms->hotplug_memory_base =
ROUND_UP(0x100000000ULL + above_4g_mem_size, 1ULL << 30);
+ if (pcms->enforce_aligned_dimm) {
+ /* size hotplug region assuming 1G page max alignment per slot */
+ hotplug_mem_size += (1ULL << 30) * machine->ram_slots;
+ }
+
if ((pcms->hotplug_memory_base + hotplug_mem_size) <
hotplug_mem_size) {
error_report("unsupported amount of maximum memory: " RAM_ADDR_FMT,
--
1.8.3.1
