And you can't get larger contiguous or aligned regions if the device
needs them.
BTW, I'm also doing userspace DMA things (similar to U-net). The driver
I'm using does exactly this. It's mingled with a lot of other junk
though and it's quite buggy, sorry I can't pass it on :-)
I agree with what Alan says in another message, a driver that kmallocs
and maps the memory to user space is a lot saner, not least because the
driver has proper control over the type of memory (GFP_DMA if needed,
for example, and none of the complications of normal user pages).
People may peek at the sound code for an example of mmaping pages used
for DMA.
-- Jamie
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