Messages in this thread | | | Date | Mon, 5 May 2003 16:58:39 -0400 | From | Pete Zaitcev <> | Subject | Re: How to DMA data from a pci device to a user buffer directly |
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> 5) My DMA controller has unlimited scatter-gather capability.
> By the way, I have tested the rest of my code by DMA the image data to a > kernel buffer allocated using kmalloc() first, then do a memcpy() to copy > the image data to a user buffer. This alternative seems to work fine.
Use mmap to make the kmalloc-ed buffer available to user application without the overhead of memcpy().
It is very wonderful that you can do s/g, so on the next stage you can kmalloc a bunch of blocks with small order (1) and use those instead of relying on bootmem allocation and Pauline's bigphysarea patch. Most older controllers cannot do it.
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