Date: Mon, 14 Aug 2000 18:16:09 GMT From: "Bill Clinton" <biffey@hotmail.com> To: freebsd-hackers@freebsd.org Subject: dma to userland address Message-ID: <F89TuHZncJfKHmj9n1x00001510@hotmail.com>
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lets say, hypothetically, that i have an ioctl interface to my device
driver that takes a buffer that looks something like:
struct {
int length;
char *buf;
} mystruct;
and lets say, hypothetically, that i wanted to dma directly
to/from 'buf'. how would i do that?
i've tried doing vtophys on buf, but that doesn't seem to work.
i've tried doing vtophys on a kernel-allocated block and the mmapping it
through /dev/mem in userland, but that doesn't seem to work either (this
may have a bug, though - it worked under linux, but was about 10x slower
than just leaving the kernel/user copy in there).
so what am i missing here?
- j
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