2-Getting started(learning note of LKD)

/*

*This is a Learning Note of Robert Love's

*By Neil Chiao ( neilchiao at gmail.com )

*From ( neilengineer.cublog.cn )

*欢迎到“新星湾()”指导

*/

 

1. Kernel basics

1. Download the official kernel from

2. Extract it using: tar jxvf xxx.tar.bz2 or tar zxvf xxx.tar.gz

3. Build it:

1) Kernel configuration

make menuconfig  (need ncurses) or

make xconfig  (need X11, qt) or

make gconfig  (need gtk+) or

make defconfig (default config)

2)Compile

make or

make –j4  (Usual practice is to spawn 1 or 2 jobs per CPU, so j4 for dual core CPU)

4. Install it if you want

make install (install the new kernel to /boot/ if you use grub, it will add a entry in menu.lst automatically)

make modules_install (install the modules to dirs in /lib)

 

2. Important features of the kernel

1. No libc  Linux kernel doesn’t have access to the C library.

2. GNU C  Linux kernel is coded in GNU C.

GNU C has its own features. e.g. :

inline functions are used for small time-critical functions.

unlikely() is used when something will unlikely happen.

3. No Memory Protection

4. Do not use Floating point in kernel

5. The kernel has a small fixed-size stack

6. Synchronization and Concurrency

7. Portability is Important