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Date:      Mon, 22 Jan 1996 13:36:59 +0100 (MET)
From:      Luigi Rizzo <luigi@labinfo.iet.unipi.it>
To:        bugs@freebsd.org
Subject:   dd /dev/mem ...
Message-ID:  <199601221236.NAA05157@labinfo.iet.unipi.it>

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Running 2.1R, I tried the following running as root:

    dd if=/dev/mem bs=32k skip=512 count=1 | dd bs=32 count=1 | hexdump

and my P100 w/ 16MB was frozen: no keyboard, no mouse, everything
still on the X screen.

the manpage says "Only offsets within the bounds of /dev/mem are
allowed.", and 512*32K is right beyond the physical RAM. However, I
have run C programs which would read beyond the limit with no problems.

Is it a bug in /dev/mem, "dd" or me ?

	Luigi
====================================================================
Luigi Rizzo                     Dip. di Ingegneria dell'Informazione
email: luigi@iet.unipi.it       Universita' di Pisa
tel: +39-50-568533              via Diotisalvi 2, 56126 PISA (Italy)
fax: +39-50-568522              http://www.iet.unipi.it/~luigi/
====================================================================



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