Help - KVM TODO_NOV2008_Sharing Memory between guests

Help - KVM TODO_NOV2008_Sharing Memory between guests

[PICT PUNE]

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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...

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Re: Help - KVM TODO_NOV2008_Sharing Memory between guests

[Avi Kivity]

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.

-- 
error compiling committee.c: too many arguments to function

Re: Help - KVM TODO_NOV2008_Sharing Memory between guests

[Anthony Liguori]

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

Re: Help - KVM TODO_NOV2008_Sharing Memory between guests

[PICT PUNE]

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On Wed, Feb 25, 2009 at 9:11 PM, Anthony Liguori <anthony@codemonkey.ws>wrote:

> 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
>

Hello Mr. Avi Kivity  and Mr. Anthony Liguori

Thanks for your early reply. We expecting the same approach. We are in
process of making clusters of free memory  and reserve these memory as a
fake PCI device for the guest  OS. this device will be then passed using PCI
passthrough  to the guest from the host. Can you please help us in faking
the free memory cluster as a PCI device. Thanking in anticipation.


Regards,

PICT Pune BE Students

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Re: Help - KVM TODO_NOV2008_Sharing Memory between guests

[Avi Kivity]

PICT PUNE wrote:
>
>
> On Wed, Feb 25, 2009 at 9:11 PM, Anthony Liguori 
> <anthony@codemonkey.ws <mailto:anthony@codemonkey.ws>> wrote:
>
>     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
>
>
> Hello Mr. Avi Kivity  and Mr. Anthony Liguori
>
> Thanks for your early reply. We expecting the same approach.

There were two approaches outlined above.  Which one do you mean?

> We are in process of making clusters of free memory  and reserve these 
> memory as a fake PCI device for the guest  OS. this device will be 
> then passed using PCI passthrough  to the guest from the host.

PCI passthrough does not make much sense in this context, is this what 
you meant?

> Can you please help us in faking the free memory cluster as a PCI 
> device. Thanking in anticipation.
>

I suggest reading the code of framebuffer devices such as vga.c.

-- 
error compiling committee.c: too many arguments to function