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native_posix: minor doc fixes

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A few minor fixes in the native_posix documentation.

Signed-off-by: Alberto Escolar Piedras <alpi@oticon.com>
This commit is contained in:
Alberto Escolar Piedras 2018-07-30 09:38:01 +02:00 committed by Andrew Boie
parent 67d2ddc6ad
commit a76fa45e4a
1 changed files with 14 additions and 12 deletions
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26
boards/posix/native_posix/doc/board.rst
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@ -420,13 +420,15 @@ This can be controlled with the ``--rt-ratio=<ratio>`` and ``-rt-drift=<drift>``
command line options. Note that both of these options control the same
underlying mechanism, and that ``drift`` is by definition equal to
``ratio - 1``.
It is also possible to adjust this clock speed on the fly with
:c:func:`native_rtc_adjust_clock()`.
In this way if, for example, ``--rt-ratio=2`` is given, the simulated time
will advance at twice the real time speed.
Similarly if ``--rt-drift=-100e-6`` is given, the simulated time will progress
100ppm slower than real time.
Note that the these 2 options have no meaning when running in non real-time
mode
mode.
How simulated time and real time relate to each other
-----------------------------------------------------
@ -475,25 +477,25 @@ The following peripherals are currently provided with this board:
This RTC can also be set to start from time 0 with the ``--rtc-reset`` command
line option.
It can also be offset by an amount with the ``--rtc-offset=<offset>`` option.
Note that these 2 options can be combined.
It is possible to offset the RTC clock value at boot with the
``--rtc-offset=<offset>`` option,
or to adjust it dynamically with the function :c:func:`native_rtc_offset`.
After start, this RTC advances with the simulated time, and is therefore
affected by the simulated time speed ratio.
Therefore the RTC speed can be adjusted by the ``--rt-ratio`` and
``--rt-drift`` command line options.
The offset and clock ratio can be dynamically adjusted using the functions
:c:func:`native_rtc_offset` and :c:func:`native_rtc_adjust_clock`
See `About time in native_posix`_ for more information.
The time can be queried with the functions :c:func:`native_rtc_gettime_us`
and :c:func:`native_rtc_gettime`. Both accept as parameter the clock source:
- ``RTC_CLOCK_BOOT``: Simulated time since boot. It cannot be offset.
- ``RTC_CLOCK_REALTIME``: Persistent time. Can be offset.
- ``RTC_CLOCK_BOOT``: It counts the simulated time passed since boot.
It is not subject to offset adjustments
- ``RTC_CLOCK_REALTIME``: RTC persistent time. It is affected by
offset adjustments.
- ``RTC_CLOCK_PSEUDOHOSTREALTIME``: A version of the real host time,
as if the host was also affected by the clock speed ratio and offset
adjustments performed to the simulated clock and this RTC. That is, normally
adjustments performed to the simulated clock and this RTC. Normally
this value will be a couple of hundredths of microseconds ahead of the
simulated time, depending on the host execution speed.
This clock source should be used with care, as depending on the actual
@ -502,7 +504,7 @@ The following peripherals are currently provided with this board:
**Entropy device**:
An entropy device based on the host :c:func:`random` API.
This device will generate the same sequence of random number if initialized
This device will generate the same sequence of random numbers if initialized
with the same random seed.
You can change this random seed value by using the command line option:
``--seed=<random_seed>`` where the value specified is a 32-bit integer