Objective 2: Compiling a Kernel
Regardless of the Linux distribution you choose, no two kernels are the same. The creators of your distribution had total freedom to customize the kernel, and so do you. Choosing and making these customizations are discussed in the next section, which covers patching. The current section explains how to apply the customizations, for which you must be able to compile your kernel.
Kernel Configuration Tools
The first step in compiling
(or recompiling) a kernel involves the make tool. One set of commands provided with this tool allows you to select and deselect the exact options you want to include and modularize for the new kernel. These configuration settings are stored in a file named .config. Historically, this file was saved within your kernel source to /usr/src/linux or /usr/src/linux-
kernel-version, but this is no longer the case. Older applications (based on the standard library called libc) required /usr/src/linux, but the introduction of a new library, glibc, eliminated that dependency. For the purposes of our examples, however, we will continue to show /usr/src/linux
This book, following LPI program objectives, will assume that kernels are built from the vanilla kernel source available at http://www.kernel.org. Many major distributions, however, on their web sites, offer new kernel sources that incorporate the distributions' own patches.
When you configure a kernel using any of the tools described in this section, you are presented ...