Obtaining the Kernel Sources

The Linux kernel has always been freely available to anyone who wants it. If you just want to recompile the existing kernel, install the kernel-sources RPM from the CD. To get the very latest vanilla version, open an FTP connection to ftp.kernel.org using your favorite FTP client and log in as anonymous. Because you are interested in the 2.6 kernel, change directories to /pub/linux/kernel/v2.6. The latest stable kernel as of this writing is 2.6.15.

Note

ftp.kernel.org receives more than its share of requests for download. It is considered a courtesy to use a mirror site to reduce the traffic that ftp.kernel.org bears. http://www.kernel.org/mirrors/ has a list of all mirrors around the world. Find one close to your geographic location and substitute that address for ftp.kernel.org.

A number of different entries are on the FTP archive site for each kernel version, but because you are interested in only the full kernel, it is only necessary to get the full package of source code. There are two of these packages:

linux-2.6.15.tar.gz linux-2.6.15.bz2

Although these are the same kernel packages, they are built using different compression utilities: The .gz extension is the gzip package, found on almost every Linux system available. The .bz2 extension is the newer bzip2 utility, which has better compression than gzip. Both packages have the same content, so download the one compressed with the program you use.

After it is downloaded, move the package to a directory other than /usr/src and unpack it. If you downloaded the .gz package, the unpacking command is tar -xzvf linux- 2.6.15.tar.gz. Otherwise, the bzip2 unpack command is tar -xjvf linux-2.6.15.tar.bz2. When it is unpacked, the package creates a new directory, linux-2.6.15. Copy it to /usr/src/kernels or move it there. Then create a symbolic link of linux-2.6 to linux- 2.6.15 (otherwise, some scripts will not work). Here is how to create the symbolic link:

# rm /usr/src/kernels/linux-2.6 # ln -s /usr/src/kernels/linux-2.6.15 /usr/src/kernels/linux-2.6

By creating a symbolic link to /usr/src/linux-2.6, it is possible to allow multiple kernel versions to be compiled and tailored for different functions: You just change the symbolic link to the kernel directory you want to work on.

Caution

The correct symbolic link is critical to the operation of make. Always have the symbolic link point to the version of the kernel sources you are working with.