On Tue, Oct 27, 2015 at 7:19 AM, Dmitry Osipenko <dig...@gmail.com> wrote:
> 27.10.2015 16:48, Krzeminski, Marcin (Nokia - PL/Wroclaw) пишет:
>
> Hello,
>> I am playing with U-Boot on ARM under qemu.
>> U-boot uses mptimer, and under qemu one second takes about 1 in real
>> world.
>> At the moment it seem that in u-boot is ok, so I have question about
>> below function.
>> Why prescaler value is multiply by 10?
>> static inline uint64_t a9_gtimer_get_conv(A9GTimerState *s)
>> {
>> uint64_t prescale = extract32(s->control, R_CONTROL_PRESCALER_SHIFT,
>> R_CONTROL_PRESCALER_LEN);
>> return (prescale + 1) * 10;
>> }
>> Regards,
>> Marcin
>>
>
> Hello Marcin,
>
> From my observation, Linux kernel is booting noticeably faster in the
> emulated guest and host machine CPU usage is lower if we "artificially"
> slowdown the MPtimer. You really shouldn't use it for the RTC, so doing
> that trick shouldn't affect guest behavior.
>
> However, maybe there is some other rational behind it and Peter C and/or
> Peter M might know better.
>
>
So I do wonder whether with your ptimer conversion this will be obsoleted,
as the rate limiter there may do the work for us.
Regards,
Peter
> --
> Dmitry
>
