On 09/24/2012 03:34 PM, Hyeongseok Kang wrote:
> Hi, I am trying to port xenomai to arm board and I have some question.

You seem to use old I-pipe patches. Have you read?
http://www.xenomai.org/index.php/I-pipe:ArmPorting

I advise you to use a newer I-pipe path, and read:
http://www.xenomai.org/index.php/I-pipe-core:ArmPorting

> 
> Why xenomai domain change the hardware timer to One-Shot mode by use
> __ipipe_mach_set_dec() ?

Because xenomai timing system is based on a one-shot timer. This allows
timing services to have a better precision than the 1ms or 10ms you
would get with a periodic timer.

> Another question, what's the purpose of TSC? Is it related to one-shot mode
> of timer?

More or less, since the ticks count is meaningless in one-shot mode,
Xenomai needs another clock source, and the TSC is this clock source on
x86, so we "emulate" a TSC on ARM. This tsc or emulated tsc also allows
to measure precisely short durations.

-- 
                                            Gilles.

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