Messages in this thread | | | Date | Mon, 08 Nov 1999 11:27:26 -0500 | From | Jeff Garzik <> | Subject | Re: locking user memory and kiobuf |
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"Tony E. Bennett" wrote: > 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.
This is a question I still have unanswered: Does map_user_kiobuf indeed map the VM into a _contiguous_ region of physical memory?
Note struct kiobuf includes an array of pages which causes some of my confusion. Is it legal/possible to do:
/* maps in four pages for read/write access */ err = map_user_kiobuf (WRITE, iobuf, (ulong) vmaddr, PAGE_SIZE * 4);
/* manipulate data in chunks greater than PAGE_SIZE */ phys = page_address(iobuf->maplist[0]); memcpy (foo, phys, PAGE_SIZE * 4);
> Since we're going to ship a driver to customers, we can't use kiobuf unless > it is standard part of the kernel. > > So, has kiobuf been accepted into the kernel proper or will it be a patch > for the forseeable future?
Yes, it is in the current 2.3.x series
-- Jeff Garzik | Just once, I wish we would encounter Building 1024 | an alien menace that wasn't immune to MandrakeSoft, Inc. | bullets. -- The Brigadier, "Dr. Who"
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