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- the pointers point to outdated version of the documentation.
- it uses runinfo/xeno-load, which are kind of outdated too, make things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.
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