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Date:      Thu, 26 Oct 1995 11:01:06 -0400 (EDT)
From:      Peter Dufault <dufault@hda.com>
To:        hackers@freebsd.org
Subject:   Physically contig memory in user process
Message-ID:  <199510261501.LAA06118@hda.com>

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I want to allocate DMA-friendly buffers that are physically contiguous
and within the isa space from a user process so that I know I can
do DMA into them without going through bounce buffers or splitting
up the transfer.

I figure I can allocate the memory in the kernel using isa_physmem
or something similar; I haven't looked through this completely yet.

What should the semantics be from a user process?  A new minor
number to mmap to in /dev/mem?  Maybe with "addr" equal to the
value desired for the low bits of the physical address?

--

Peter Dufault               Real Time Machine Control and Simulation
HD Associates, Inc.         Voice: 508 433 6936
dufault@hda.com             Fax:   508 433 5267



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