NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/comp/unix/internal/1980

Internet Message Format | 1992-11-22 | 1.6 KB

Xref: sparky comp.unix.internals:1980 comp.unix.programmer:5395
Path: sparky!uunet!usc!rpi!batcomputer!munnari.oz.au!uniwa!aldetec!hausler
From: [e-mail] (Graham Hausler)
Newsgroups: comp.unix.internals,comp.unix.programmer
Subject: HELP: kernel routines for device driver
Message-ID: <[e-mail]>
Date: 20 Nov 92 08:45:31 GMT
Organization: Aldetec Pty Ltd, Perth West Australia
Lines: 27

I have reached a brick wall in attempting to implement my first device
driver on a Motorola MVME187 running System V/88 R32V3.
I need some/all of the following details clarified ....

1. Can I access physical memory (not in IO space) directly from a
   device driver, assumming I have removed this memory from usage by unix?
   I want the physical memory at a fixed address, and hence cannot
   allocate in virtual address space and then derive the physical address
   (assuming I can even manage that !!)

2. If I cannot access directly, what supplied routines within the kernel are
   good candidates for trying to perform the accesses ie 'fake DMA' type
   transfers and the like ... If you suggest routines like undisjointio(), I
   would appreciate some details as my documentation does not describe it!

If any of the above solutions seem long-winded and horribly indirect, maybe
someone can explain how unix performs it's shared memory operations when you
can directly attach/access the same physical memory???

Please email any responses, I will forward relevant information to anyone
that requests it ....

Thanks
Graham Hausler
--
Internet:   [e-mail]      --> GEMCO, Perth, Australia.