i386/62717: ATA or similar read bug.

[abc at ai1.anchorage.mtaonline.net]

>Number:         62717
>Category:       i386
>Synopsis:       ATA or similar read bug.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-i386
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Feb 11 16:40:08 PST 2004
>Closed-Date:
>Last-Modified:
>Originator:     Joe Public
>Release:        i386 FreeBSD 4.9-RELEASE
>Organization:
no org
>Environment:
FreeBSD 4.9-RELEASE FreeBSD 4.9-RELEASE #0: Tue Nov 25 19:10:45 AKST 2003     /usr/src/sys/compile/MYKERN  i386

>Description:
when reading a large file (a gigabyte image of a hard drive
                creating with strings(1)) using a simple shell loop such as
                'while [ 1 ]; do read a; echo $a; done < big-file',
                once every few 1000 lines, a directory listing (ls) of
                the current directory is echoed in the midst of the data.
                no pattern is detected - but it seems to occur more often
                after 40,000 lines or so have been read.
                this seems like a potentially very dangerous bug.

                this is an example of the output (with a line number):

                00070805: v+ file1 file2 file3 file4 file5 file6 file7
                          ^^ the listing seems to occur after short reads.
                00078682: jT| file1 file2 file3 file4 file5 file6 file7
                          ^^^
                00078701: file1 file2 file3 file4 file5 file6 file7 ]0
                          the carets denote actual data             ^^
                00079300: >u file4 file5
                          ^^ occasionally a deficient ls listing is output.

>How-To-Repeat:
possibly create a large file as data for the loop given.
                possibly a Promise Ultra100 ATA card is required.

>Fix:
don't know - this would be very time consuming to debug.
>Release-Note:
>Audit-Trail:
>Unformatted: