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SubjectRe: locking user memory and kiobuf
>>>>> "Alan" == Alan Cox <alan@lxorguk.ukuu.org.uk> writes:

>> kiobuf sounds perfect for a problem we have. Currently I use mmap() to map
>> pages from __get_free_pages() into user space for dma. This is not totally
>> satisfactory, tho, in part because the resulting group of pages is not mapped
>> contiguously into kernel.

Alan> If you have a situation where that is hard to handle you can vmalloc a block
Alan> of memory then map that into user space. drivers/char/bttv.c does it. Its
Alan> ugly and bttv needs to switch to kiovecs in 2.3.x if I get time.

Is vmalloc'd memory locked down and thus suitable for dma? Somehow I thought
it was paged...

>> Since we're going to ship a driver to customers, we can't use kiobuf unless
>> it is standard part of the kernel.

Alan> Whose kernel 8)

Why, everybody's of course :-)

--tony

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