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Weird output from pmap

To: linux-mips@linux-mips.org
Subject: Weird output from pmap
From: "Erik Niessen" <erik.niessen@gmail.com>
Date: Tue, 5 Sep 2006 08:55:18 +0200
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Hi,

I am using an embedded development board with a mips 4kEC on it. I use buildroot for building a
rootfs and the toolchain.

I cross compiled a helloword app.
When I look at the output of pmap I see the following

/helloworldmips(86)
00400000 (4 KB)        r-xp (00:0a 33243002)   linux/test/helloworldmips
10000000 (4 KB)        rw-p (00:0a 33243002)   linux/test/helloworldmips
10001000 (4 KB)        rwxp (00:00 0)        [heap]
2aaa8000 (20 KB)       r-xp (00:07 1795853)  /lib/ld-uClibc-0.9.27.so
2aaad000 (4 KB)        rw-p (00:00 0)       
2aaed000 (4 KB)        rw-p (00:07 1795853)  /lib/ld- uClibc-0.9.27.so
2aaee000 (48 KB)       r-xp (00:07 1795861)  /lib/libgcc_s.so.1
2aafa000 (252 KB)      ---p (00:00 0)       
2ab39000 (4 KB)        rw-p (00:07 1795861)  /lib/libgcc_s.so.1
2ab3a000 (368 KB)      r-xp (00:07 1795855)  /lib/libuClibc-0.9.27.so
2ab96000 (256 KB)      ---p (00:00 0)       
2abd6000 (8 KB)        rw-p (00:07 1795855)  /lib/libuClibc- 0.9.27.so
2abd8000 (16 KB)       rw-p (00:00 0)       
7fd49000 (84 KB)       rwxp (00:00 0)        [stack]
mapped:   1076 KB writable/private: 128 KB shared: 0 KB

It seems that the bss segments of the shared libs are protected and mapped to the zero page. I don't see this
when I run this on a linux pc. I have the following questions:
- Why is this segment protected? Accessing results in a seg fault.
- Why is it so big (252k/256K)?
- How much memory is physically allocated for this segment?

Thanks for reading sofar

Erik Niessen
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