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From: long@uicsgva.csg.uiuc.edu
Newsgroups: comp.lang.c
Subject: Help wanted: Data segment layout
Message-ID: <3300001@uicsgva.csg.uiuc.edu>
Date: 18 Mar 90 01:36:18 GMT
Lines: 25
Nf-ID: #N:uicsgva.csg.uiuc.edu:3300001:000:845
Nf-From: uicsgva.csg.uiuc.edu!long    Mar  5 11:57:00 1990



I would like to know the data segment layout of a C program
on Unix (Sun OS). For the following example, I found some extra 
variables were inserted before the first global variables 
(marked as ? in the following figure). 


/* --- example.c ---*/           +----------+
int a = 0;                       |  text    |
int b[32];                       +----------+ <- etext
                                 |    ?     |
main()                           +----------+
{                                |    a     |
...                              +----------+ <- edata
}                                |    b     |
                                 +----------+ <- end
                                 |          |

Now my questions are: does anyone know what they are? 
Does they vary from program to program?

Thank you very much.

junsheng long