By default, the EMT thread of the last vCPU handles expired timers. When
running VirtualBox with 2 vCPUs, it sporadically happens that the EMT
thread of the second CPU clears an 'interrupt pending' flag for the first
vCPU after changing the state of a timer device model, which is not
expected by our Genode-specific code (failed assertion '!_irq_win' in the
recall handler).
The problem did not occur yet when letting the EMT thread of the first
vCPU handle the expired timers, which is done by this commit as an interim
fix until the problem has been further investigated.
Issue #1660
26924c9bcd