Re: Help - KVM TODO_NOV2008_Sharing Memory between guests

[Anthony Liguori <anthony@codemonkey.ws>]

Avi Kivity wrote:
> PICT PUNE wrote:
>> In reference to the November 2008 todo list on Qumranet Website
>>
>> we are a group of college students working on this todo:
>>
>> *Add a qemu interface for sharing memory between guests. Using a pci 
>> device to expose the shared memory is probably a good starting point.
>> *
>> Can anyone suggest us some starting point or a possible approach for 
>> the same...
> 
> Write a PCI device that exposes a BAR containing RAM.  Implement the RAM 
> by mapping a shared memory segment or a file.  Write a guest driver to 
> use this shared RAM.
>

Or implement a virtio device that can advertise available shared memory 
segments.  Have guest allocate its own memory to send to host that 
becomes the shared memory segment.

Expose shared memory mappings via a virtual file system (similar to 
hugetlbfs or ramfs).

Using PCI BARs implies static shared memory mappings.  For a long 
running VM, you're likely to want to support dynamic shared memory mappings.

Also exposing a simple signaling mechanism with this too would allow for 
shared ring queues to be implemented in userspace between guests.

Regards,

Anthony Liguori