How To Compile Your Own Kernels, Modules, Tinboot (NAND boot), and More for Beginners

[natemcnutty]

Below is a copy of my full build script for NAND. Haret users will have to make a few changes which I'll explain later. Just copy/paste it into gedit and save as fullbuild.sh and run it from terminal. You may need to change the directory paths at the beginning if you don't put them where I recommended.

#!/bin/sh
#-------------------------------------------------------------------------
# Build Script for linux-msm-rhod-nand (Android on HTC) kernel, modules, XIP, and NBH
#-------------------------------------------------------------------------
#
# Set the following variables
# ANDROID -- Root director for Android files
ANDROID=~/android
# TINBOOT -- tinboot directory
TINBOOT=$ANDROID/tinboot-linux-msm
# KERNEL_PATH -- directory containing the linux-msm kernel source
KERNEL_PATH=$ANDROID/linux-msm-rhod-nand
# TOOLCHAIN_PATH -- directory containing the arm toolchain
TOOLCHAIN_PATH=$ANDROID/prebuilt/linux-x86/toolchain/arm-eabi-4.4.0/bin/arm-eabi
# MODULES_PATH -- directory for modules
MODULES_PATH=$TINBOOT/modules
#-------------------------------------------------------------------------

# do some cleanup before building if zImage already exists
echo "Removing previous zImage"
if [ -f $TINBOOT/kernel/zImage ] ; then
     rm $TINBOOT/kernel/zImage
fi

# build kernel and modules
#export ARCH=arm
cd $KERNEL_PATH
make clean
make ARCH=arm htc_msm_nand_defconfig
make ARCH=arm CROSS_COMPILE=$TOOLCHAIN_PATH- INSTALL_MOD_PATH=$MODULES_PATH zImage modules modules_install
[ $? -eq 0 ] || fail "Kernel compilation failure"

# copy all drivers to single level directory for compression
cd $MODULES_PATH
KERNMODS=$(find -name "*.ko")
if [ ! -d $ANDROID/androidupdate/data/modules ] ; then
     mkdir -p $ANDROID/modules
fi
for i in $KERNMODS ; do
     cp $i $ANDROID/modules
done

# make squash files
KER_VER="$(cat $KERNEL_PATH/include/config/kernel.release)"
mkdir -p $ANDROID/androidupdate/system/lib/modules
mksquashfs $ANDROID/modules $ANDROID/androidupdate/system/lib/modules/$KER_VER.sqsh

# compress modules to a tar.gz and move to output
echo "Outputting modules to Desktop"
cd $ANDROID/androidupdate
tar -cvzf $ANDROID/androidupdate.tgz data system
rm -rf $ANDROID/modules
rm -rf $ANDROID/androidupdate/system/lib/modules

# clean up modules
rm -Rf $MODULES_PATH
mkdir $MODULES_PATH
rm -Rf $KERNEL_PATH/lib/modules

# move new kernel
mv $KERNEL_PATH/arch/arm/boot/zImage $TINBOOT/kernel

#-----start build XIP-----
# remove old XIP if it exists
cd $TINBOOT
if [  -f xip/rhod ]; then
    rm xip/rhod
    echo Deleting old XIP
fi

# make XIP folder if it does not exist
if [ ! -d "$TINBOOT/xip" ] ; then
mkdir $TINBOOT/xip
fi

# compile tinboot XIP
echo "Start compiling tinboot/xip for rhod....."
$TOOLCHAIN_PATH-as  tinboot/tinboot2.S -o tinboot.o --defsym rhod=1 --defsym MTYPE=2292
$TOOLCHAIN_PATH-objcopy tinboot.o -O binary tinbootxip
mv tinbootxip xip/rhod

# cleanup tinboot
rm tinboot.o

# make sure XIP build was successful
if [ ! -f xip/rhod ] ; then
    fail "XIP build failed. XIP file was not found."
fi

#-----start build NBH-----
# clean up previous log file
if [ -e "tools/log" ]; then
rm tools/log
fi

# compile tinboot
cp tools/rhod_payload2 os.nb.payload

echo "Inserting tinboot into payload"
wine tools/osnbtool -c os.nb.payload 1 xip/rhod >> tools/log
mv os.nb.payload.NEW os.nb.payload >> tools/log

echo "Inserting blank imgfs into payload"
wine tools/ImgfsToNb.exe  tools/imgfs.bin os.nb.payload os-new.nb.payload >> tools/log

echo "Creating os.nb portion of nbh"
tools/nbmerge < os-new.nb.payload > os-new.nb

echo "Creating NBH"
wine tools/yang.exe -F RHODIMG.NBH -f os-new.nb -t 0x400 -s 64 -d RHOD****0 -c 11111111 -v Tinboot -l WWE >> tools/log

# clean up payloads
mv RHODIMG.NBH $ANDROID/RHODIMG.NBH
rm os.nb.payload
rm os-new.nb.payload
rm os-new.nb

# clean up tinboot directory
rm -rf xip

What the heck is zImage, modules, tinboot, rootfs, initrd, and System.ext2?
This section will be updated slowly as I have time.

The zImage is the kernel (which is required to run the operating system). We currently use the linux kernel 2.6.27.46.

The modules are your drivers. These are a matched pair with the zImage/kernel. It is also important to clean up the modules periodically when building the kernel/modules or you will start running out of space

Awesome explanation of the kernel and its modules here: http://www.howtogeek.com/howto/31632...at-does-it-do/

Tinboot is the bootloader for running Android from the NAND. Currently, we put initrd.gz and the zImage on the NAND while the zImage, rootfs, and System.ext2 are pulled from the SD Card.

RootFS is a special type of ramfs file system. It basically lets us use part of the memory as a partition for caching files. This gives us a nice performance boost

Initrd is an initial RAM disk that is temporary and used only for booting. Generally it uses a slightly different scheme than rootfs does.

System.ext2 is your file system. This is technically your hard drive where all of the Android files and applications are stored. It uses the ext2 file system which is an extended file system designed specifically for linux.