Re: Need help creating CDs that will pass mediacheck
| From: Dan Trobridge <linuxddt(a)gmail.com>
| Still no resolution. I have been able
| to get disc1 to pass media check, but no others.
I suspect that you are having another manifestation of the problem I just
posted:
https://www.redhat.com/archives/fedora-list/2005-March/msg02774.html
I have hit this problem in several different ways with 2.6 kernels.
Grrr.
Here's a crude solution that has worked for me: pad the .iso by adding
a bunch of bytes at the end. Those bytes won't influence the ISO-9660
file system, but will allow the goofy device driver to read ahead past
the end of the file system without getting an I/O error.
How much padding? I used a couple of megabytes of zeros, if I
remember correctly, but I now think that I know the magic minimum
number: 33 * 2k. This is the length of the reads that were failing
(see my previous message) so it ought to be a bound on the amount of
spurious readahead. It might be the case that the 33 can very under
some conditions -- I don't know where it comes from and I'm too lazy
to read the driver code at the moment.
How can you pad the .iso?
Method 1 (untested):
dd if=/dev/zero bs=2048 count=33 >>file.iso
Method 2 (untested):
When burning with cdrecord, add the parameter:
padsize=33s
(I don't actually know if a sector, in cdrecord's terminology
is 2048 bytes; the manpage suggests so.)
I find it interesting the the cdrecord(1) manpage, in its description
of the padsize option, says:
Use this option if your CD-drive is not able to read the last
sectors of a track or if you want to be able to read the CD on a
Linux system with the ISO-9660 filesystem read ahead bug.
If you do test this, please report back whether it worked or not.
Please cc it to me personally since I don't read this list regularly.