Sparse/unsparse images

For sparse and unsparse android images,

http://forum.xda-developers.com/showthread.php?t=1081239

compiling fastboot.exe

File location in android,
system/core/fastboot/*

Command to compile,
make -j2 win_sdk

binary will be build here,
out/host/windows-x86/bin/fastboot.exe

Andriod Toolbox

Android comes with a user space utility called Toolbox which is not busybox. It is at system/core/toolbox. But with very limited features.

For using the busybox,

1) Git clone from http://git.busybox.net/busybox/
2) To cross compile with arm tool-chain and building it as static, used the following command.
$ make -j32 CROSS_COMPILE=/projects/mob_tools/CodeSourcery/Sourcery_G++_Lite/bin/arm-none-linux-gnueabi- -I/projects/mob_tools/CodeSourcery/Sourcery_G++_Lite/arm-none-linux-gnueabi/libc/usr/include/ CFLAGS=--static
3) for installing the busybox,

Building Individual Components in Android

Run

source build/envsetup.sh

Then you can use mm command to compile any Android.mk individually

For example to compile the android Toolbox.

cd system/core/toolbox.

mm