On Tue, 22 Nov 2022 12:35:56 -1000 Bryan Angelo <bang...@gmail.com> wrote:
> Related follow up. > > When I add memory to a running VM via hotplug, QEMU preallocates this > memory too (as expected based on your explanation). When I subsequently > remove memory added to the VM via hotplug, QEMU does not always appear to > free the underlying memory. > > For example: > > -m 8G,slots=1,maxmem=12G > > QEMU using 8G, VM shows 8G total. > > object_add memory-backend-ram,id=mem1,size=4G > device_add pc-dimm,id=dimm1,memdev=mem1 > > QEMU using 12G, VM shows 12G total. > > After using the VM for a bit: > > device_del dimm1 > object_del mem1 > > QEMU using 12G, VM shows 8G total. > > Does it just so happen that the VFIO device is using memory that QEMU > allocated/pinned for the hotplug device and therefore QEMU cannot free it? > Or is there something else going on here? Is this a Windows guest? Hot adding memory is easy, hot removing it is much more difficult. I'm under the impression that Windows doesn't actually support hot-remove. For example, what happens if you try to added it again? Is the slot still in use? Does memory size increase by another 4G? Thanks, Alex _______________________________________________ vfio-users mailing list vfio-users@redhat.com https://listman.redhat.com/mailman/listinfo/vfio-users
