Guide by AndreEli - XDA Post

There are two main parts to the z4mod process, kernel patching and the lagfix updates. Without going too much into technicalities, here is how the process works and how you can get it to work.

1 --- Kernel Patching

How it works:

Using the linux shell script or the online patching tool you patch kernel to allow it to run one of the lag fixes in the first post

What kernels:

Technically ANY kernel. The point of this is to be kernel agnostic. Custom and stock kernels SHOULD be patchable. Report any errors in the patching process in this thread.

What to do:

1. Find the tar/zip file of your desired kernel

2. Extract the zImage file from the archive

3. Upload to (CAN'T POST URL, LINK IS SOMEWHERE IN THREAD), and click patch

4. Download the patched kernel image (the zImage file)

5. Flash your new kernel image using Odin/Heimdall

[From RyanZA: If using Odin, set the PDA to the .tar file. No pit, csc, radio. Repartition must be unchecked, everything default.]

6. Apply one of the lag fix updates in the OP

2 ---- The Lag Fixes

How it works:

The relevant update.zip files can be used to apply lagfixes on the kernel patched using the z4build method described above

What kernels:

Any kernel that has been patched with z4build.

What to do:

1. Download the desired lag fix option. The auto.update.zip is recommended and will select either ext2/3/4 based on what the kernel is capable of

2. Save to the sdcard root. REMEMBER TO RENAME TO update.zip

3. Boot into recovery mode and apply update.zip

4. Reboot

3 ----- What about rooting?

Firstly, all z4build-patched kernels include 2erecovery. This means that they can be rooted using the update.zip methods in android 2.1 builds. With this kernel the OCLF root from the market or the update.zip root method floating around xda for 2.1 will both work.

If you wish you can try patching the CF rooted kernel with z4build, flashing that kernel, then applying the lagfix. However if you don't particularly need any feature of the CF rooted kernel other than root it seems more work than necessary.

Note: If you apply an unpatched CF rooted kernel AFTER the applying a patched, lagfixed z4build kernel, YOU WILL LOSE YOUR DATA AND LAGFIX, since the CF rooted kernel cannot read ext2 and will overwrite that partition with rfs.

In case it is not obvious, to root:

1. Ensure your kernel has been patched with z4build

2. Grab the android 2.1 update.zip file, and apply it via three-button recovery

3. You are now officially fu... er, rooted.

4 ------ What is converted

At the moment it is only data (from what I can tell). In the future I guess system, dbdata, whatever can all be created as ext2/3/4 with the right update.zip file.

5 ------- BONUS

If you have already flashed to JP6 froyo, RyanZA has provided a pre-flashed JP6 kernel for you to use. Just flash this with Odin/Heimdall, and then apply the update.zip you want

[From RyanZA: That JP6 kernel is available here: jp6.tar]