Re: [Xenomai-help] RTDM

[Jan Kiszka <jan.kiszka@domain.hid>]

[-- Attachment #1: Type: text/plain, Size: 2176 bytes --]

Patrick wrote:
> 
> Jan Kiszka a écrit :
>> Patrick wrote:
>>   
>>> Hy,
>>>
>>> I don't understand the difference between rtdm function and standard function.
>>> For exemple what is the diffrence between rtdm_printk and printk 
>>>     
>>
>> Technically? None these days (printk is provided RT-safe by
>> Adeos/I-pipe), but it documents that the message may be printed from RT
>> context. And who know if some future RTDM implementation may not have to
>> differentiate internally again...
>>
>>   
>>> or rtdm_malloc 
>>> and malloc ?
>>>     
>>
>> You mean kmalloc (malloc is user space only)? rtdm_malloc provides
>> memory from a dedicated pool (dedicated to Xenomai, excluding Linux) and
>> uses a predictable allocator (as long as the memory usage pattern is
>> predictable). kmalloc is non-deterministic, and is shared with the whole
>> Linux kernel.
>>   
> Yes I use kmalloc... sorry
> So kmalloc and rtdm_kmalloc is exactly the same ?

They share the same purpose, but details differ, just look at the
function arguments...

> 
>>   
>>> I am developping an RT driver so I must simply used only functions rtdm ?
>>>     
>>
>> Regarding the two services above: Depends on the context. If they run in
>> non-RT driver cleanup or device instantiation context, you should
>> continue to use standard Linux services. Just for usage from RT contexts
>> (tasks, IRQ handlers (please don't allocate memory in the latter
>> context, though...)) switch to those RTDM variants.
>>
>> Jan
>>
>>   
> For IRQ handlers I use the rt_intr_ functions it's not right ? what is the difference between this functions and th rtdm_irq ?

Besides details, the main point is that you shall not mix APIs in your
driver if you want to keep it portable to future RTDM environment.

> 
> Do you have an simple trivial exemple of rtdm driver with irq ?

We still need to add such a tutorial to the RTDM series. In the
meantime, you could have a look at irqbench from the testsuite for a
more simple scenario. But, of course, you can also dig inside the other
RTDM drivers in-tree or beyond, they are just not that simple.

Jan


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 250 bytes --]