On Mon, 14 Oct 2024 20:56:59 +0200 Heiko Carstens <hca@xxxxxxxxxxxxx> wrote: > On Mon, Oct 14, 2024 at 04:46:12PM +0200, David Hildenbrand wrote: > > Let's finally add s390 support for virtio-mem; my last RFC was sent > > 4 years ago, and a lot changed in the meantime. > > > > The latest QEMU series is available at [1], which contains some more > > details and a usage example on s390 (last patch). > > > > There is not too much in here: The biggest part is querying a new diag(500) > > STORAGE_LIMIT hypercall to obtain the proper "max_physmem_end". > > > > The last two patches are not strictly required but certainly nice-to-have. > > > > Note that -- in contrast to standby memory -- virtio-mem memory must be > > configured to be automatically onlined as soon as hotplugged. The easiest > > approach is using the "memhp_default_state=" kernel parameter or by using > > proper udev rules. More details can be found at [2]. > > > > I have reviving+upstreaming a systemd service to handle configuring > > that on my todo list, but for some reason I keep getting distracted ... > > > > I tested various things, including: > > * Various memory hotplug/hotunplug combinations > > * Device hotplug/hotunplug > > * /proc/iomem output > > * reboot > > * kexec > > * kdump: make sure we don't hotplug memory > > > > One remaining work item is kdump support for virtio-mem memory. This will > > be sent out separately once initial support landed. > > Besides the open kdump question, which I think is quite important, how > is this supposed to go upstream? > > This could go via s390, however in any case this needs reviews and/or > Acks from kvm folks. we're working on it :)
