Re: [PATCH] Inter-VM shared memory PCI device

Avi Kivity
2010-03-08T09:56:06Z

On 03/06/2010 01:52 AM, Cam Macdonell wrote:
> Support an inter-vm shared memory device that maps a shared-memory object
> as a PCI device in the guest. This patch also supports interrupts between
> guest by communicating over a unix domain socket. This patch applies to the
> qemu-kvm repository.
>
> This device now creates a qemu character device and sends 1-bytes messages to
> trigger interrupts. Writes are trigger by writing to the "Doorbell" register
> on the shared memory PCI device. The lower 8-bits of the value written to this
> register are sent as the 1-byte message so different meanings of interrupts can
> be supported.
>
> Interrupts are supported between multiple VMs by using a shared memory server
>
> -ivshmem<size in MB>,[unix:<path>][file]
>
> Interrupts can also be used between host and guest as well by implementing a
> listener on the host that talks to shared memory server. The shared memory
> server passes file descriptors for the shared memory object and eventfds (our
> interrupt mechanism) to the respective qemu instances.
>
>

Can you provide a spec that describes the device? This would be useful
for maintaining the code, writing guest drivers, and as a framework for
review.

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