Hallo,
I don't have any experience with rtlinux, but I think it must be
possible to use the BIGPHYSAREA-patch.
You give the amount of physical memory you want to be able to allocate as a
boot parameter. From this memory pool you can alloc memory with an extra set of
functions.
Linux don�t touch this memrory (no paging), it's on piece of physical
memory (DMA-acces is possible), the amount of memory you can get is
only limited by the amount of the memory your computer has.
http://www.polyware.nl/~middelin/hob-v4l.html
Wolfram
> I'm writting a Device Driver for a high bandwith acquisition board that can
> do DMAs but without scater/gather
> As the board as almost no internal fifo, I'm loosing datas if I have to
> interrupt after each Page (4kB) Of transfert.
> (The time needed to handle the interrupt is too big and the board internal
> fifo explode)
>
> => How can I get LARGE DMA BUFFERS ? (256kB for example)
>
> PS: the datas are coming in bursts, so if i use this kind of large DMA, I
> have some time between DMAs as the bandwith is almost 0 every 256kB.
>
> => How can i remap this buffer to user space ? (Is that possible with rtl or
> even linux ?)
> (I don't want to copy datas as the CPU as to do a lot of work with these
> datas, and I don't want to loose CPU time just for data copy...)
>
>
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