The kernel in post #1 has been modified as follows:
The only critical patch was the addition of Uma6 BORD support in include/linux/tivoconfig*.h .
# kernel 2.4.18 patches (applied against the 4.0 tivo.com kernel tarball)
# fixups for "normal" non-ism build system
# deleted -mcpu option
# added fast-sysmips patch
# floating point signal fix
# turned off CONFIG_BLK_DEV_INITRD
# enabled CONFIG_EXT3_FS, CONFIG_JBD, CONFIG_TMPFS, CONFIG_NFSD,
# added LBA48, intentionally broke ideturbo
# added init= command line support
Also, for an updated x86 bootpage binary and quick instructions on finding your active kernel and root partitions, see this thread.
On another note, here are a few useful reference threads. Read and understand them before you ask questions in the uma6fix discussion thread, and don't reply with non-technical material or support issues.
Tips for 4.0 on your S2 DTivo (originally written for Uma4 users)
killhdinitrd 0.9.x (learning to compromise Series2.0 PROM security)
tivoapp patches (misc. customization though binary patches)
Superpatch-4all (Home Media Option / Multi Room Viewing for DTiVo)
USB2 backport from 2.4.27 to 2.4.4/2.4.18/2.4.20 (faster MRV transfers)
FsAllocateFunction tmk assertion failure on 4.x+
You are responsible for reading and understanding all information in this thread. A 4.x on RID support thread is provided to answer questions that are not covered here. Several error-filled "guides" making use of this software exist. Support posts regarding these guides belong in the thread dedicated to that guide; if they are found elsewhere, they are subject to deletion. Do not follow these guides (or any other step by step howto) if you do not understand what you are doing.
Compatibility and board identification:
uma6fix.o and the replacement dssapp are mandatory to run 4.x on a Uma6 board. The new dssapp should not be used on a Uma4 board; however, the remainder of the files and procedures in this thread will work correctly on a Uma4. Loading uma6fix.o is harmless on a non-Uma6 board, as it detects whether or not it is needed.
Uma4 boards are DirecTV combo units whose service ID prefix is 1x1. For example: 101, 121, 151. They do not have a Receiver ID number on the back panel. These are all Series2.0 units.
Uma6 boards are DirecTV combo units whose service ID prefix is 3x1. For example: 301, 321, 351, 381. They have a Receiver ID number on the back panel. These are all Series2.0 units.
HD Series2.0 boards (3x7) and Series2.5 boards (5x1) will not run 4.x without serious changes. 4.x does not support ATSC tuners, the new BCM7317 IC, etc.
if you're going to restore an InstantCake to a drive larger than 137 gig. use the new LBA48-40DD iso
*see these threads for more info
Common LBA48 mistakes (was: "expand" after the fact...)
Should boot CDs support LBA48? (split from: Common LBA48 mistakes)