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DateFri, 14 May 1999 19:53:59 +0200
FromGabor Lenart <>
SubjectRe: [VFS] move active filesystem
On Thu, May 13, 1999 at 03:48:42PM -0600, WANG,YIDING (HP-SanJose,ex1) wrote:
> Linux has DMA memory allocation limitation to max. 128K - 24 bytes.
> Does anyone know how to break the limitation in driver to allocate more DMA
> memory, say 256K?

And what about a more inteligent DMA memory allocator ? I mean, in case
of fragmented memory it's very frequent not to success to allocate DMA
memory by kernel (eg by sound/floppy modules). Why does not kernel
moves some memory, changing some pagetable entries etc to create
contigous memory area suitable for DMA (in low 16M for ISA DMA, care of
page boundaries etc). If there's enough memory to do it, it would be
only some memory moving action to get the suitable place.

(I don't know too much about Linux kernel internals, maybe DMA memory
allocating is something atomic operation which blocks the kernel too long
to do such an operation I described below ?)

Thanx : Gabor,

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