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From: ajc@bbn.com (Anthony J. Courtemanche)
Newsgroups: comp.sys.mips
Subject: Use of mmap()
Message-ID: <48700@bbn.COM>
Date: 23 Nov 89 15:02:23 GMT
Sender: news@bbn.COM
Lines: 21


I'm (still) working on a device driver for an M2000 running release
4.20 of RISC/os.  I've been told that I can use mmap() to map kernel
resources into a user process address space.  I want to do this for
a device driver that has set aside some kernel memory for a device to
DMA into; I want user processes to be able to see this memory.

mmap() seems like what I want, but I do not know what to pass
as the file descriptor argument that is associated with the kernel
memory that I want to map into the user's address space.  If anyone
knows how to make a "file descriptor associated with a memory device"
(words taken from the mmap() man page), please let me know.  I've also
been told that a good example is in the file mem.c, but I do not have
a source liscence and mem.c was not included on my system (I just got
mem.o in the device driver area).

Thanks for any help you can give.


--Anthony Courtemanche
  ajc@bbn.com