Hi, sorry for the delay. On Tue, Feb 19, 2013 at 07:39:40PM -0300, Erlon Cruz wrote: > On Tue, Dec 18, 2012 at 10:41 AM, Vasilis Liaskovitis < > vasilis.liaskovi...@profitbricks.com> wrote: > > > This is v4 of the ACPI memory hotplug functionality. Only x86_64 target is > > supported (both i440fx and q35). There are still several issues, but it's > > been a while since v3 and I wanted to get some more feedback on the current > > state of the patchseries. > > > > > We are working in memory hotplug functionality on pSeries machine. I'm > wondering whether and how we can better integrate things. Do you think the > DIMM abstraction is generic enough to be used in other machine types?
I think the DimmDevice is generic enough but I am open to other suggestions. A related issue is that the patchseries uses a DimmBus to hot-add and hot-remove DimmDevice. Another approach that has been suggested is to use links<> between DimmDevices and the dram controller device (piix4 or mch for pc and q35-pc machines respectively). This would be more similar to the CPUState/qom patches - see Andreas Färber's earlier reply to this thread. I think we should get some consensus from the community/maintainers before we continue to integrate. I haven't updated the series for a while, but I can rework if there is a more clear direction for the community. Another open issue is reference counting of memoryregions in qemu memory model. In order to make memory hot-remove operations safe, we need to remove a memoryregion after all users (e.g. both guest and block layer) have stopped using it, see discussion at http://lists.gnu.org/archive/html/qemu-devel/2012-10/msg03986.html. There was a relevant ibm patchset https://lists.gnu.org/archive/html/qemu-devel/2012-11/msg02697.html but it was not merged. > > > > Overview: > > > > Dimm device layout is modeled with a normal qemu device: > > > > "-device dimm,id=name,size=sz,node=pxm,populated=on|off,bus=membus.0" > > > > > How does this will handle the no-hotplugable memory for example the memory > passed in '-m' parameter? The non-hotpluggable initial memory (-m) is currently not modelled at all as a DimmDevice. We may want to model it though. thanks, - Vasilis
