Re: [Xenomai-help] RTDM mmap alternative

[Rodrigo Rosenfeld Rosas <lbocseg@domain.hid>]

Hi, Jan. I think I wasn't very clear on my post. I'll try to clarify 
what I meaned...

Jan Kiszka escreveu:
> Rodrigo Rosenfeld Rosas wrote:
>   
>> Hi Jan, I'm back on this discussion.
>>
>> At the time I asked you, you told me to do the mmap on driver
>> initialization.
>>
>> But now, I realized that, since I'll be using RTDM, how could I use
>> mmap from RTDM, even if in a non RT-context?
>>     
>
> Which mapping step are you now referring to, the one to get the large
> physical DMA area inside the kernel address space or the one to map
> kernel addresses to user space?
I'm refering to the second case. I want to map the kernel addresses to 
user space but I'm not very sure if I can do the same thing I did in my 
previous mmap call on an ioctl. I mean, I don't know if the kernel does 
something else in a mmap call... And since I don't have a mmap handler 
I'm a bit confusing...

>  Already checked the related LDD3 chapter for this?
>   
Yes, but it didn't answered to my doubts...
>> I'm a bit confusing...
>>
>> What would be others alternatives for avoid copying the video frames
>> in a RTDM driver?
>>     
>
> Either map or copy, there is no third way. The point is just which
> mapping functions to use and when.
>   
That is what I would like to know... Which mapping functions are 
available? Actually, if I can use the same I used on my previous mmap 
handler that is good. I'm just unsure if something will be missing or not...

I have also noted that there is no poll or select handler on RTDM. Are 
there some plans to include them?

Thank you,

Rodrigo.


		
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