retitle 426781 qemu: virtual machine has impossible timing characteristics.
thanks
I've has problems similar to this one, so I'm merging them into this
report. In short:
- As described, the serial port is never busy.
- The same is true for the keyboard controller.
- The system timer runs on real-time, not on virtual time. When I have
loads of debugging output on irq0, then qemu never executes a program,
because it is too busy writing that output. That's perfectly fine.
However, when I redirect stdout to a file, thus speeding up the
execution of the virtual machine, it does execute code outside the irq
handler. This means that the behaviour may not be reproducible on
different machines, for example. This can hinder debugging, for
example when trying to show a problem to others by sending them some
code.
The best would be IMO to have qemu use its own time, and programs
running inside it should be completely unaffected by the actual speed
and load of the machine. Of course this may be very hard to implement,
I wouldn't know about that. :-)
Thanks,
Bas
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