[yifanlu]

Try writing ALL files, not just /opt. There are many new system binaries and startup scripts. Then, to use the old kernel, copy /lib/modules from 3.3. Then it would be 98% working if not 100%. If you look at my Kindle 3.2 updater script, you can see that running 3.2 on the Kindle 2 only took 2 extra folders + modules and one patch to an existing file (to get framebuffer working). So 4.0 shouldn't be that bad.

P.S: I've said this in the other thread, but it's physically impossible to "break" the recovery kernel by only touching /opt. No operating system files are in /opt (just amazon's Java framework app that acts as the GUI). In addition the recovery script is in the kernel which cannot be modified without reflashing. That's like saying by deleting a word document, you broke the BIOS.

EDIT: I'll do this if I have time, but I think the only thing you need to do to get 4.0.1 working on Kindle 3 without backporting the kernel is:
1) Backup /lib/modules
2) Backup /etc/kdb.src/luigi
3) Backup /usr/lib/libdtp_module.so, /usr/lib/libdtp_module.so.0, and /usr/lib/libdtp_module.so.0.1 if you want 3G (.so, and .so.0 are links to .so.0.1)
4) Reflash rootfs with the 4.0.1 rootfs using dd. If the FS is larger then the Kindle 3 one, just rsync or cp -a all the files. Remove TTS if you don't have enough space.
5) Restore the files you backed up.

I'm like 99.9% sure this will work for the Kindle 3. Then you can run the updater script I wrote on the Kindle 2 if you want it there too. (With modifications to recognize 4.0.1 of course). If this doesn't work, post the logs. Again, I'd do this if I had the time.