Re: [Qemu-devel] [PATCH] target-arm: Use common CPU cycle infrastructure

[Peter Maydell]

On 5 October 2015 at 15:09, Paolo Bonzini <address@hidden> wrote:
>
>
> On 03/10/2015 00:41, Peter Maydell wrote:
>> > What I meant to ask was, do you see any reason for cpu_get_ticks() to 
>> > exist?
>> > If no architecture besides i386 wants to use it, perhaps the code should be
>> > moved there.
>>
>> OTOH various non-x86 things do use the closely related cpu_get_real_ticks(),
>> and the implementation of cpu_get_ticks() is very closely related to
>> the other clock code in cpus.c.
>
> cpu_get_real_ticks() is returning the host cycle counter;
> cpu_get_ticks() is stopping/resuming it when the VM is stopped/resumed.
>  In other words, cpu_get_real_ticks() is to cpu_get_ticks() what
> QEMU_CLOCK_REALTIME is to QEMU_CLOCK_VIRTUAL.

...but it seems wrong to have anything in the simulation care
about the host cycle counter, especially since on some hosts
the underlying implementation is terrible.

thanks
-- PMM