I filed a bug report with kernel.org awhile back and it was resolved...I was unable to mount dvd's over 2GB without using ide-scsi. There is a patch at the bottom of http://bugme.osdl.org/show_bug.cgi?id=1930 by Luca Tettamanti that fixes the issue. You may want to include it in future gentoo-*-sources. Reproducible: Always Steps to Reproduce: 1. 2. 3.
in gentoo-dev-sources-2.6.9-r12