[Bug 186512] kernel prevents proper CD checking (mediacheck/install fails)

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https://bugzilla.redhat.com/show_bug.cgi?id=186512


David Tonhofer <d.tonhofer at m-plify.com> changed:

           What    |Removed                     |Added
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                 CC|                            |d.tonhofer at m-plify.com




--- Comment #40 from David Tonhofer <d.tonhofer at m-plify.com>  2009-01-03 19:15:39 EDT ---
I seem to have hit this bug on Fedora 10. I thought the SCSI/SATA drivers had a
bug until I found this report. Here we go:

With an LG GDRH20N SATA DVD-ROM:

-- Media Check fails 100% (tested DVDs, (live) CDs, several burns...)
-- "Independent Media Check" using another system works (dump the ISO
   image, see below, then check the SHA1 sum against the official sum)
-- Installation fails in a totally weird manner
   (e.g. at the very end, anaconda says "no kernel images installed" or
    arbitrary packages are not found)
-- Starting the same system from a PATA drive found in the attic with
   the same media works nicely (installation not yet tried, will try)
-- Media check passes if "ide=nodma" kernel option is given. Yowza!

Additionally:

-- Booting the system to Fedora 10 Live CD using aforementioned PATA
   drive, then dumping an ISO image (in this case, F10-x86_64-Live.iso)
   off the DVD-ROM if "ide=nodma" has NOT  been set results in a: 

   -- correctly-sized
   -- but slightly corrupted image

   The dump was done with "dd if=/dev/sr0 of=/tmp/corrupted.iso"
   It is probably not of big interest to know the exact differences,
   but a little perl program to cut the dump into 10K blocks and hash
   these, applied tp both original ISO and dumped ISO reveals 61 10K
   blocks with differences, *spread throughout the image* (not only the
   end affected).

Now going to have drink or two.

How to hash 10K blocks:

#!/usr/bin/perl
use Digest::MD5 qw(md5 md5_hex md5_base64);
$file = $ARGV[0];
open(FILE,$file) or die "Could not open $file: $!\n";
binmode FILE;
my $buffer;
my $size = 1024*10;
my $read;
my $pos = 0;
while (($read = read(FILE, $buffer, $size)) > 0) {
   my $digest = md5_hex($buffer);
   my $end    = $pos + $size - 1;
   print "$digest [$pos,$end] $size\n";
   $pos += $size;
}
close(FILE);

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