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From: lwa%mit-csr@sri-unix.UUCP
Newsgroups: net.unix-wizards
Subject: Re: pdp11 loader options
Message-ID: <2047@sri-arpa.UUCP>
Date: Sat, 11-Jun-83 13:17:00 EDT
Article-I.D.: sri-arpa.2047
Posted: Sat Jun 11 13:17:00 1983
Date-Received: Sun, 12-Jun-83 22:07:46 EDT
Lines: 21

The -i and -n options to the pdp-11 loader actually do different
things.  -n produces a load image with separate "text" and
"data" segments, such that the text segment is read-only and
can be shared.  The data segment is relocated to begin at
the next 4K word boundary above the end of the text segment
(_etext) so that it will mapped by a different mapping register -
this allows the text and data segments to be non-contiguous in
physical memory.

The -i option goes further - it produces a program linked to run
with separated instruction and data (I and D) spaces.  In this
case both the text segment and the data segment are relocated to
begin at virtual address 0; the processor determines from the
type of reference (instruction fetch or not) whether the address
is to be mapped using the I-space mapping registers or the D-space
mapping registers.

Programs linked with -n can be run on any pdp-11; programs linked with
-i can be larger, but will only run on 11/44's, 45's, 50's, 55's, and 70's.
					-Larry Allen
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