The architecture of the kernel changed a lot between those two versions. There was a lot of changes, more than what I could reasonable fit in a quick comment.

The architecture of the kernel changed a lot between those two versions. There was a lot of changes, more than what I could reasonable fit in a quick comment. Here is a quick overview: https://wiki.gentoo.org/wiki/Kernel/Migrate_2.4_to_2.6 https://wiki.gentoo.org/wiki/Kernel/Migrate_2.4_to_2.6