Rodrigo Rosenfeld Rosas wrote: > 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...
What precisely? I suggested to look at remap_pfn_range() or io_remap_page_range(). Do you see problems when using one of them? >>> 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... As I haven't written such a driver as well yet, I cannot say which one will fit. You will have to go though the LDD explanations and play with it (which means e.g. finding out where to obtain all required arguments - should be feasible). > > I have also noted that there is no poll or select handler on RTDM. Are > there some plans to include them? > Only rough plans. This requires a lot of work and restructuring, I'm afraid. And I doubt that it's worth it. Do you see an urgent use-case for poll/select under RT? The only real-life use-case that we came across was ACE/TAO. Jan
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