[Bug 37876] Re: Kernel does not read DVDs, no automount

Mike C thenewme91 at gmail.com
Fri Sep 1 22:06:30 UTC 2006

I'm going to attempt to summarize the bug's info to date.

Based on above comments in the thread:
This bug is believed a REGRESSION between Ubuntu 6.06 and the previous release 5.10. The problem is that some written DVDs (but not all) can be read under other OSes, and in fact, Breezy (5.10), but not in Ubuntu Dapper (6.06). Some users have reported success with Kubuntu Dapper (6.06) as well.

It is confirmed there is a problem that is preventing certain users from
reading certain DVD discs on certain drives. What the problem is, and
what is causing it, is unknown or unconfirmed.

AFAIK, Reading DVDs isn't performed in user-space, it is done in the
kernel. Therefore, a FIRST STEP to troubleshooting would to see if
running under a *user-built kernel* built with kernel-package configured
with the required DVD-reading options (notably, device support, either
IDE, SCSI, or whatever your drive needs, as well as ISO9660 and UDF file
system support) works.

If it does, then the kernel-building system and the kernel-builders'
policies need to be revised. Maybe the archives for the mailing list for
the kernel team (if any) or the wiki or whatever need to be consulted to
see if they knew and if there was reason.

It might also help to see if this regression appeared in the upstream
vanilla Linux kernel; although I assume if the config was done right, it
should work, since I can burn from my custom 2.6.17 kernel on my Debian
box (the other one). This would mainly be of note if upstream vanilla
(or someone else) dropped drivers for certain disc drives.

Additional info that may help: A user with access to similar (preferably
identical) or dual/triple/quad-boot system with Windows
(presumably/preferably XP; other versions' support are reported flaky,
and Vista is in beta), Ubuntu Dapper (6.06), Breezy (5.10), Kubuntu
Dapper (6.06), or a combination of the four, one of which is Ubuntu
Dapper, to burn DVDs under Windows, Breezy, and Dapper, and see which
ones are readable under which systems. Debian unstable or another system
may also be a useful benchmark if available. (The above reports seem
inconsistent, so a unified report on all the same hardware would show
whether or not this is a software problem. Also, if it shows Dapper can
read all DVDs except for those produced by Dapper (and maybe Debian
Unstable), then it means there is a problem in the burning software --
my first hunch would to be to look for bugs/regressions or
incompatabilities in growisofs/dvd+rw-tools, maybe in OPC or similar.
The changelog for said program may help.)

Further info that may help: A diff between the configs of the different
kernel images for Dapper and Breezy. Assuming the report that the bug
doesn't affect Kubuntu Dapper is true, a diff of the configs for the
kernel image in Kubuntu versus Ubuntu would also help. (If, for example,
by chance, the Dapper kernel has UDF file system support as modular (or
omitted) where Breezy/Kubuntu didn't/doesn't, loading (via modprobe or
similar) the module, if one was built, might help.)

Kernel does not read DVDs, no automount

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