[Qemu-devel] What events should be handled in iohandler context?

[Anton Kuchin]

Hi,

I'm trying to understand contexts and handlers/notifiers and a bit 
confused about two contexts living in main loop: qemu_aio_context and 
iohandler_ctx. It is mentioned in the iohandler_ctx comment that 
qemu_aio_context can't be reused because "iohandlers mustn't be polled 
by aio_poll(qemu_aio_context)" but there is no exlanation why.

I tried to find examples and failed to understand why virtio-net 
eventfds are registred to iohandler_ctx with generic virtio callback 
virtio_device_start_ioeventfd_impl() but TX bottom-half and handlers of 
back-end TAP use qemu_aio_context.

Can you explain a little bit why we need some fds to be polled and some 
not to be polled? And how can I choose which context is right for me?

Thanks in advance for your help!

Anton