at91_enthus wrote:
> On Mon, Jan 24, 2011 at 9:25 PM, Gilles Chanteperdrix <
> [email protected]> wrote:
>
>> at91_enthus wrote:
>>> On Mon, Jan 24, 2011 at 8:41 PM, Gilles Chanteperdrix <
>>> [email protected]> wrote:
>>>
>>>> at91_enthus wrote:
>>>>> Hi.
>>>>>
>>>>> I was testing Xenomai on my AT91SAM9G20-based board and tried to adapt
>>>> the
>>>>> code found here:
>>>>> http://www.armadeus.com/wiki/index.php?title=Xenomai:Blinking_LEDs .
>>>> By the way, this code is ridiculous. It creates a real-time task to
>>>> write to some non real-time device, which makes the real-time task
>> useless.
>>>>
>>> I know.
>> Yes, but this example is bad in many ways:
>> - first it uses xenomai api to create a real-time task, and uses write
>> which causes the real-time task to switch to secondary domain;
>> - the Makefile does not use xeno-config, which have been the recommended
>> way of getting the compiler flags since day 1;
>> - it nullifies SIGTERM and SIGINT, which is a dubious decision, and
>> could lead people to believe that they should do the same when using
>> Xenomai, whereas there is no such requirement.
>> - the pointers point to outdated version of the documentation.
>> - it uses runinfo/xeno-load, which are kind of outdated too, make things
>> uselessly complicated, and in any case, tell you to type Ctrl-C to
>> interrupt the program, which is bound to fail if anything goes wrong,
>> since SIGINT is neutralized in the program.
>>
>>> That's why I went to mmap().
>> That is not really the right solution either. I admit that for driving
>> leds, it may be a bit overkill, but anyway, what you should do is write
>> an RTDM driver for driving the leds. Keeping the driver separated from
>> the application will allow the same program to run on other platforms
>> where driving the LEDS is done differently without changing much of the
>> application code. In other word, the application/driver separation is a
>> sane one.
>>
>> Anyway, mmap should work.
>>
>> (I chose that sample code because, for
>>> now, I am only learning to use basic functions)
>>>> Wrong test here. Should be "if (aic_base == MAP_FAILED)"
>>> Indeed, my program fails miserably when I check the mapping of AIC, not
>>> PIOB's. And yet, I just can't figure why in the non-Xenomai code, AIC
>>> mmap-ing works fine.
>> Well errno might give you a clue. Do you have FCSE enabled?
>>
>> Regards.
>>
>> --
>> Gilles.
>>
>
> FCSE is enabled. errno returns 22 (invalid argument).
best effort or guaranteed? Please activate FCSE messages. How big is
MAP_SIZE?
--
Gilles.
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