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From: pgd@bbt.se (P.Garbha)
Newsgroups: comp.unix.questions
Subject: Re: Are pointers in a shared memory segment valid for a different process?
Keywords: shared memory, pointers, IPC
Message-ID: <1990Aug25.061151.4858@bbt.se>
Date: 25 Aug 90 06:11:51 GMT
References: <838@qusunc.queensu.CA> <115@ctbilbo.UUCP>
Organization: .
Lines: 15

In article <115@ctbilbo.UUCP> ray@ctbilbo.UUCP (Ray Ward) writes:

>The most usual approach is to pick an address at which to map in the
>shared memory segment in *both* programs.  If you pick an address that

Some systems/architectures might have restrictions to the allowable
addresses chosen. In a application using shared memory, that I have
made, the program that creates the shared memory, let's the operating
system choose the address, and write it as the first word in shared
memory. The next program to link up, then let's the os map just the
first word of the shared memory, reads the starting address, unmaps
the memory, and finally maps it to the correct starting address, and 
length.

I was using Xenix/386 (The intel 386 i a segmented architecture)