The i8257 DMA controller uses an idle bottom half, which by default
does not cause the main loop to exit. Therefore, the DMA_schedule
function is there to ensure that the CPU relinquishes the iothread
mutex to the iothread.
However, this is not enough since the iothread will call
aio_compute_timeout() and go to sleep again. In the iothread
world, forcing execution of the idle bottom half is much simpler,
and only requires a call to qemu_notify_event(). Do it, removing
the need for the "cpu_request_exit" pseudo-irq. The next patch
will remove it.
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
19d2b5e6ff