Re: [Qemu-devel] Want to be part of Memory Hotplug

[Vasilis Liaskovitis]

Hi Senthil,

On Mon, Feb 04, 2013 at 04:17:30PM +0530, kumaran wrote:
> Hi,
> 
> I am Senthil, doing post graduation in IIT Bombay,India.
> 
> I am looking for some problems related to KVM as part of my research
> work. I read about memory hotplug and other open issues in KVM.
> 
> Can i be part of your work regarding memory hotplug.
> 
> My Experience in KVM:
> 
> - I have implemented Record and Replay feature in KVM
> - I have good hands on experience with KVM and QEMU's code base
> - Thorough knowledge about QEMU's architecture and PCI emulation
> - I have implemented Record and replay for Intel Ee100Pro network
> interface and for IDE disks (including DMA)
> 
> If I get chance, I can spend around 5 dedicated months on this work.
> Please let me know your interest.

thanks for your interest in the memory hotplug effort. You are welcome to
contribute. Memory hotplug is still not in mainline qemu. It is a qemu-wide
project rather than a kvm-specific one.
Some possible directions are:

- reviewing / improvement suggestions on v4 here:
http://lists.nongnu.org/archive/html/qemu-devel/2012-12/msg02693.html

- define the qom interface for Dimms. The current patches use a memory bus
abstraction (DimmBus) where Dimms can plugin. That's definitely one choice. Some
people have suggested using <links> from the i440fx/mch (in general the memory
controller device of the emulated system) to the Dimm devices. That's similar
to how CPUs are re-modelled in qom-cpu patchsets I think. The final dimm
interface has not been agreed upon yet.

- Add acpi native memory hotplug support for q35/ich9. The current code creates
paravirtual Dimmbus + Dimms, without emulating real hotplug-capable memory
controller hardware.

- Make sure ejection is safe i.e. all users of a hotplugged MemoryRegion 
(not only guest/CPUs but also qemu block layer) have stopped using the memory,
before actually freeing it.

make sure to include the qemu list (cc'ed) in order to let everyone know what 
you
are working on and to get feedback.

thanks,

- Vasilis