Newsgroups: comp.os.linux
Path: rpi!maniattb
From: maniattb@cs.rpi.edu (Bill Maniatty)
Subject: Re: shared libs - can everyone be happy with this?
Message-ID: <qddysb=@rpi.edu>
Nntp-Posting-Host: fornax.cs.rpi.edu
References: <NOP.92Aug16220027@theory.Mankato.MSUS.EDU> <1992Aug17.065450.28834@colorado.edu> <d-dyhz_@rpi.edu> <1992Aug17.152210.23427@riacs.edu>
Date: Mon, 17 Aug 1992 18:02:50 GMT
Lines: 49

In article <1992Aug17.152210.23427@riacs.edu>, laredo@cc.gatech.edu (Nathan I. Laredo) writes:
|> In article <d-dyhz_@rpi.edu> maniattb@cs.rpi.edu (Bill Maniatty) writes:
|> >In article <1992Aug17.065450.28834@colorado.edu>, drew@ophelia.cs.colorado.edu (Drew Eckhardt) writes:
|> >|> In article <NOP.92Aug16220027@theory.Mankato.MSUS.EDU> nop@theory.Mankato.MSUS.EDU (Jay A. Carlson) writes:
|> >|> >In article <1992Aug15.042420.18914@serval.net.wsu.edu> hlu@phys1.physics.wsu.edu (Hongjiu Lu) writes:
|> >    [Stuff Deleted] 
|> >|> Also, if we ever unbreak Linux, writing to code space should trigger
|> >|> a segmentation fault - it's like it is now because the estdio library 
|> >|> was broken, and wrote to the code. 
|> >    Does linux permit self modifying code (by design or bug)?
|> >    This seems like a pretty bad ``feature''.
|> 
|> Hopefully we won't start another nasty chain here.. but someone correct
|> me if I'm wrong, but I've always been from the school that said that
|> all static variables went into the code space, otherwise how would
|> they be loaded in.
        [Stuff Deleted]

I don't have a machine to run Linux on (yet :-) so I have to ask a stupid
question here.  My original post may have an incorrect assumption about
how memory management is performed.

        I thought that traditional C compilers/linkers used the following segment
structure for memory management (for more details see Comer's Designing
Systems - the Xinu Approach)

        text - instruction space
        data - initialized data space
        bss - uninitialized data space
        stack - stack segment
        (typically the heap and stack are at opposing ends of the same segment,
                and grow towards each other)

I think data and bss could be combined into a single segment on 80x86.

How does linux do memory management at compile/run time?
Also what flavors of memory protection does linux support?

Bill

|> Nathan I. Laredo (this spot: $9) Internet: gt7080a@prism.gatech.edu 
|> uucp:  ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!gt7080a
|> "Having had the correct view is nothing meritorious: statistically,
|>  it is almost inevitable..."  -- Mr. Palomar,  On biting the tongue

-- 
|
|       maniattb@cs.rpi.edu - in real life Bill Maniatty
|