RE: Alloc and lock down large amounts of memory

From: Mike Galbraith (
Date: Tue Aug 20 2002 - 23:31:04 EST

At 03:08 PM 8/20/2002 -0500, Bhavana Nagendra wrote:
> >
> > Curiosity: why do you want to do device DMA buffer
> > allocation from userland?
>I need 256M memory for a graphics operation. It's a requiremment,
>can't change it. There will be other reasonably sized allocs in kernel
>space, this is a special case that will be done from userland. As
>discussed earlier in this thread, there's no good way of alloc()ing
>and pinning that much in DMA memory space, is there?

Not that I know of. It seems to me that any interface that tried
to provide this would have to know what kind of device is going
to DMA from/to that ram.

Usually, when someone needs a large gob of contiguous ram,
folks suggest doing the allocation in kernel, and early.


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