How_to_build_Uni

How to build (modified by Alberto96, credits to stratosk)
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Prerequisites
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Basic knowledge of Linux and compiling is required to be able to build a kernel. 
You need a modern Linux box (preferably) with git and latest linaro toolchain optimized for Cortex-A8 installed (install this in gearkernel/toolchain folder)
(http://forum.xda-developers.com/showthread.php?t=2098133).

First you need to setup the directory that within you will clone the kernel and 
initramfs repository. In this guide we will setup them in ~/gearkernel but you 
can do it in any directory you want.


1. Setup build environment

In your home directory (~/) create the directories:

mkdir -p gearkernel/output/galaxys
mkdir -p gearkernel/output/captivate
mkdir -p gearkernel/output/vibrant
mkdir -p gearkernel/output/galaxysb

The above will be the output directories for Galaxy S, Galaxy S B (Brazil), Captivate and Vibrant versions.

The directory structure is complete. Now, you are ready to clone GearKernel code.

2. Setting up repositories

While you are still in ~/gearkernel directory do the following.

Clone the main kernel repository branch 'universal':

git clone -b universal git://github.com/Alberto96/samsung-kernel-aries

Due to the fact that github does not preserve file permissions, I also included
initramfs for each SGS variant as a tarball. You need to do the following 
only the first time you clone the ics-ramdisk repo. Of course, you can safely
do this every time you fetch new code.

Captivate, Galaxy S B and Galaxy S shares the same ramdisk. (except recovery)

Extract all Recoveries:

tar zxvf ics_rec_init.tar.gz
tar zxvf ics_rec_init_v.tar.gz
tar zxvf ics_rec_init_c.tar.gz
tar zxvf ics_rec_init_b.tar.gz

To build an Universal Kernel do this:

cd samsung-kernel-aries/ics-ramdisk
tar zxvf gear_combo.tar.gz 
tar zxvf gear_combo_v.tar.gz

3. Kernel configuration

You need to set the correct toolchain path:

1) Open with gedit (or with your favourite editor) sbuildgear.sh located in samsung-kernel-aries folder and search this string : export CROSS_COMPILE=
2) Edit the path after the = and change it with your toolchain/bin path

Example :

export CROSS_COMPILE=/gearkernel/toolchain/bin/arm-gnueabi-

to

export CROSS_COMPILE=new path toolchain/bin

I use 4 files to keep kernel's configuration for each variant.
The files are placed in arch/arm/configs directory and they are named:

GearKernelUni_galaxys_defconfig
GearKernelUni_galaxysb_defconfig
GearKernelUni_captivate_defconfig
GearKernelUni_vibrant_defconfig

When, you will run the build script, the proper configuration will be used
according to the selected variant (please see next section).
If you need any change kernel configuration, you have to edit these files
before the building procedure. 
Leave these files unchanged, if you want gearkernel's default settings.

You are ready to build!


4. Building the kernel

I create a script that automates the building procedure. The script can accept
2 arguments: 
a) Kernel variant: galaxys, captivate, vibrant, galaxysb 
b) s argument to build the kernel for hugemem compatible ROMs

If you run the script without arguments will build the normal version 
for galaxys.

Do this for galaxys kernel compile:

cd ~/gearkernel/samsung-kernel-aries
./sbuilduni galaxys

and for 's' version:
./sbuilduni galaxys s

Wait few minutes (time depends on the machine - on my build machine 4-5 minutes) and hopefully 
the compilation will end.
Watch the output for possible errors. A successful compilation must NOT have any
error. It may have some warnings, but you can safely ignore them. 
If everything was OK, you must have the zImage file in 
~/gearkernel/samsung-kernel-aries/arch/arm/boot directory.
Also the script will automatically prepare the CWM flashable zip and the 
ODIN/Heimdall flashable in ~/gearkernel/output directory (in respective variant)

Now, you are ready to flash the kernel!