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Date:      1 May 2002 14:10:42 -0000
From:      atk2@arctic.org
To:        freebsd-stable@FreeBSD.ORG
Subject:   dd of=/dev/eide_drive bs=8192 if=/dev/mem kills system
Message-ID:  <20020501141042.5400.qmail@twinlark.arctic.org>

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I have 4.5-stable (updated it last night to get the ata 133 support for
my disk drive). I was doing a bit of crude benchmark and used
dd if=/dev/eide_drive bs=8192 of=/dev/null to test read speed
(iostat -c 100 indicates about 40MB/sec sustained (i.e., not cache) - if
 it is accurate)

Anyways I then tried to test write speed with 

dd of=/dev/eide_drive bs=8192 if=/dev/mem

and the system hanged. I forget the exact symbols for eide_drive but it
was an unmounted slice - yea I know if it worked it would have killed the
slice - but the slice is unused so I didn't care). I'm not overly concern
that the above killed the system as it isn't needed for daily use -- just
noting it in case it is a kernel bug... (not kernel didn't panic - it 
hanged - I waited about 5 minutes then did a reset -- nothing responded during
that time including mouse (was running X) and hdd light on case was off)

Alan

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