Anthony Liguori wrote:
Jacob Gorm Hansen wrote:
OK, I actually got the impression that using XCS was the easiest way
around the problem, as you seem to need a lot of code for setting up
your own channel (which I can copy-paste from somewhere I am sure).
For just using notify, it's quite simply. The control channels are
complicated because of the ring queue stuff. If you were implementing
this as a virtual device in vm-tools (of course, I'm not bias ;-)), all
you would do is open /dev/evtchn and add that to the set of listener fds
(see the console device for an example of this).
You would also need to allocate a port for notifications (vmm_alloc_port
in vm-tools or xc_evtchn_bind_interdomain otherwise). The easiest thing
to do would be to use a well known endpoint (anything above 10 should be
relatively safe for now although you'll probably need to negotiate it in
the future).
Right now, in my domU driver I have:
gfx_irq = bind_evtchn_to_irq(117);
printk("got irq %d\n", gfx_irq);
request_irq(gfx_irq, gfx_interrupt, SA_SAMPLE_RANDOM, "gfx", 0);
/which should get me interrupts when channel 117 gets notified, right?
When you get a read event on /dev/evtchn, all you do is read a 2 byte
value from it. This will be the port the event happened on. You'll
also have to unmask the event by writing that same value back to the
device.
Can I setup my own event channel in the guest, and still access it
using /dev/evtchn in dom0?
Hmm from looking at the code in drivers/xen/evtchn/evtchn.c, it seems if
I write to this device, I can unmask local event channels, but there is
no notion of a target domain.
If I want to notify eventchannel #117 in, say, domain 5, how can I do
that from dom0 using /dev/xen/evtchn?
Thanks,
Jacob
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