Path: utzoo!utgpu!water!watmath!focsys!larry
From: larry@focsys.UUCP (Larry Williamson)
Newsgroups: comp.unix.microport
Subject: /etc/shmcreate, how does it do it?
Message-ID: <162@focsys.UUCP>
Date: 5 Aug 88 20:11:00 GMT
Reply-To: larry@focsys.UUCP (Larry Williamson)
Organization: Focus Automation Systems, Waterloo, Ontario.
Lines: 27


I've mailed this same query to Microport hoping to get the answer
straight-from-the-horses-mouth (so to speak :-), but I though I'd
post it as well, just in case Microport does not want divulge some
AT&T secret.

I'd like to know how /etc/shmcreate attaches a physical piece of
memory to a shared memory segment.  I have a need to do this from
within a user process, and I'd rather not do it by executing shmcreate.

Is the process the same on the 286 and 386 versions of Unix? Or are
there some differences?

On the same subject, although the 386 does not have a 64K segment
size limit to its addressing, the parameters to shmget() seem to
limit the size of a shared memory segment to 64K. The second
parameter specifies the size in bytes of the segment, and this is
an int. Therefore, only 65535 bytes can be specified! Is this, infact
true, or is there something that I've overlooked?

Thanks,
   Larry
-- 
Larry Williamson               Focus Automation Systems Inc.
watmath!focsys!larry                Waterloo, Ontario
                                      (519) 576-8558
                                      (519) 746-4918