Re: [Qemu-devel] Broken Microblaze timer

[Peter Chubb]

>>>>> "Paolo" == Paolo Bonzini <address@hidden> writes:

Paolo> Il 14/06/2012 04:29, Peter Crosthwaite ha scritto:
>> Obviously this sucks as a patch, but without this hack, the system
>> freezes on boot. I managed to ascertain that its coming from the
>> ptimer used by the system timer (hw/xilinx_timer.c). The CPU is
>> either halted and never resumes, or the timer is flooding with halt
>> requests and the CPU never gets another look in.
>> 
>> The question is, is this a failure in ptimer, xilinx_timer or the
>> async framework? Can ptimer be misused such that the CPU is locked
>> up?

Paolo> Yes, this looks like the ptimer is flooding the iothread so
Paolo> that the CPU does not get an occasion to run.

Paolo> Perhaps you want to limit the rate of the hw/xilinx_timer.c to
Paolo> something like 1000 Hz or something like that.

Changeset cf36b31db209a261ee3bc2737e788e1ced0a1bec Limit ptimer rate
to something achievable
is meant to fix this in the cases where the timer is auto-reloaded.

xilinx_timer.c always uses the timer in one-shot mode, so it needs to
be fixed in there.



--
Dr Peter Chubb                                  peter.chubb AT nicta.com.au
http://www.ssrg.nicta.com.au          Software Systems Research Group/NICTA