Path: utzoo!utgpu!water!watmath!focsys!larry
From: larry@focsys.UUCP (Larry Williamson)
Newsgroups: comp.unix.microport
Subject: Physical memory access with SystemV/AT
Message-ID: <185@focsys.UUCP>
Date: 10 Jun 88 15:25:07 GMT
Reply-To: larry@focsys.UUCP (Larry Williamson)
Distribution: na
Organization: Focus Automation Systems Inc. Waterloo, Ontario.
Lines: 30


How does one obtain access to physical memory in System V/AT?

I have a video processor board that I need to access. This board
is accessed through a 1Meg buffer mapped on any 1Meg boundry in
the 286's address range.

I would ideally like to be able to do whatever shmcreate does and
create a shared memory segment that I would then use to access the
memory on this board. But I would like to be able to create a 
segment that is the full 1 Meg memory size, or at least be able
to create 4 256K segments.

I would like to do something like:
	shmcreate 0x800000 800000 1048560
to create a 1Meg shared memory segment at the 8meg address location.

Shmcreate restricts segment sizes to 64K. So I must use something 
else, but what?

If my only option is to use shmcreate and I have to restrict my
segment size to 64K, then I will. But even this may not work as
there may be a limit to the number of 64K segments that can be
created. I would need at least 16 of them.

Thanks, larry
-- 
Larry Williamson                      Focus Automation Systems
UUCP: watmath!focsys!larry    608 Weber St. N, Waterloo, Ontario N2V 1K4
                                          +1 519 746 4918