ajc@bbn.com (Anthony J. Courtemanche) (11/23/89)
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
rogerk@mips.COM (Roger B.A. Klorese) (11/28/89)
In article <48700@bbn.COM> ajc@bbn.com (Anthony J. Courtemanche) writes: >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. It's the fd on which the user has opened /dev/your-device. -- ROGER B.A. KLORESE MIPS Computer Systems, Inc. phone: +1 408 720-2939 928 E. Arques Ave. Sunnyvale, CA 94086 rogerk@mips.COM {ames,decwrl,pyramid}!mips!rogerk "I want to live where it's always Saturday." -- Guadalcanal Diary