Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!amdcad!ames!think!husc6!cca!mirror!datacube!ftw
From: ftw@datacube.UUCP
Newsgroups: comp.unix.wizards
Subject: Motorola Sys V help
Message-ID: <106600031@datacube>
Date: 11 Feb 88 16:38:00 GMT
Lines: 50
Nf-ID: #N:datacube:106600031:000:2475
Nf-From: datacube.UUCP!ftw    Feb 11 11:38:00 1988


Attention: Motorola System V R3V3 gurus (please?)

Background:

I've ported character driver from the Sun 3 environment to the Sys V
environment on a Motorola 2616.  She seems to work, but there are a few
remaining nits I'd like clarification on:

I need to buy LOTS of VME address space, and map it into a user-addressable
chunk of virtual memory.  Of course, I don't want the address space either
cached or paged.  Right now, I do this with appropriate calls to Sys V's
shared memory functions, and I use the Motorola extensions that allow one
to buy physical addresses.  This is of course done from user space, and
doesn't involve my driver.  The scheme has some deficiencies, though.  One
must be root to map physical addresses, and worse, the shared memory
descriptors are not released when the user program exits (or dies).  I have
a description of a function called sptalloc(), but the constants used in
one of the arguments (PG_P and PG_LOCK) don't exist in any of my headers.
Could someone tell me more about sptalloc()?

As a side note, I have heard from a Motorola FAE that shared memory under
R3V3 is broken in some significant fashion.  He was not able to tell me
exactly how; only that it is broken.  Funny part is that it seems to work
well for me.  Can anyone confirm or deny shared memory bugs in this version?


Interrupt handlers and the infamous sysgen(1M) utility.  Does *any* description
of a sysgen "script" exist?  It must have taken me about two or three days to
figure out that in order to get a minor device number passed as an argument
to an interrupt handler, I need to say "This is a character device." instead
of "This is an interrupt device." in the driver attributes field.  Along
those lines, I read that the actual argument to an interrupt handler is
the minor number, possibly up-shifted and or-ed with some low bits of the
interrupt vector, depending on how many vectors fan in to one handler.  This
just doesn't seem to be true on my system however.  It is also interesting to
note that if I tell sysgen that such-and-such is a character device, and
I don't specify what the minor number is, the kernel that is generated will
hang after displaying the System V banner.



				Farrell T. Woods 

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