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Re: role of RTC
- To: Arnaud Mouiche <arnaud dot mouiche at inventel dot fr>
- Subject: Re: [ECOS] role of RTC
- From: Jonathan Larmour <jlarmour at redhat dot com>
- Date: Thu, 19 Jul 2001 20:05:59 +0100
- Cc: ecos-discuss at sourceware dot cygnus dot com
- Organization: Red Hat UK Ltd.
- References: <5.0.2.1.0.20010719181013.00a80498@193.54.84.101>
Arnaud Mouiche wrote:
>
> we can see that each processor port defines those functions (in the
> 'xxxx_misc.c' file):
>
> - void hal_clock_initialize(cyg_uint32 period)
> - void hal_clock_read(cyg_uint32 *pvalue)
> - void hal_delay_us(cyg_int32 usecs)
>
> what kind of timer should a processor use to define correctly those functions ?
One that can deliver a regular interrupt after a specified time.
> what is the link between the RTC and the scheduler. If there is one, where
> is it defined ?
Each platform defines CYGNUM_HAL_INTERRUPT_RTC which indicates which
interrupt is used for the kernel RTC. The kernel then attaches to that
interrupt, initializes the clock with hal_clock_initialize, and then just
has to wait for the interrupts.
> where is defined the time slicing of the scheduler ?
kernel/VERSION/src/common/clock.cxx has the real time clock stuff. Look at
the end of the file. The RTC DSR calls the scheduler timeslice function.
Jifl
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