Messages in this thread |  | | | Date | Fri, 14 May 1999 19:53:59 +0200 | | From | Gabor Lenart <> | | Subject | Re: [VFS] move active filesystem |
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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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