Re: [PATCH RFC] Driver to support shared memory with interrupts with broadcast

[Cam Macdonell <cam@cs.ualberta.ca>]

Michael S. Tsirkin wrote:
> On Thu, Jul 30, 2009 at 01:29:52PM -0500, Anthony Liguori wrote:
>> Cam Macdonell wrote:
>>> This driver allows the guest VM to access shared memory between other guest
>>> that is a POSIX shared memory object on the host.  The driver can also send
>>> interrupts by writing to the DoorBell register.
>>>
>>> With interrupts, the ioctl must specify the ID of the VM to receive the
>>> interrupt or '255' for broadcast to all active VMs.  The 'arg' parameter is the
>>> destination VM and 'cmd' is the interrupt code.  The value written to the
>>> register is a bit messy.  32-bits are written to the register, the upper 16 are
>>> the destination VM, and the lower 16 are the interrupt 'code' that the
>>> destination guest will receive.  Implemented codes (see the interrupt handler)
>>> either call up on the device's semaphore or wake up on the wait_event queue.
>>> These codes' uses are at the discretion of the driver so they could be
>>> customized.
>>>
>>> For ioctls that read values from the device (such as for getting the global ID
>>> of the guest) the arg parameter is unused.
>>>
>>> Cam
>>>   
>> I think you should just use Michael's uio_pci driver.  I don't think we  
>> have a need for a new kernel interface.
> 
> If that's what you want to do, an example device that generates
> interrupts in response to config writes can be found here:
> http://www.archivum.info/qemu-devel@nongnu.org/2009-07/01548/%5BQemu-devel%5D_%5BPATCH%5D_qemu:_test-irq_device
> 

Thank you, I'll have a look.