More Kernel Chapter 3

More Kernel - Chapter 3

We’re moving forward this week with kernel configuration, heading toward helping you create your own custom kernel for your Linux system. First off today, a correction. In my original instructions on Tuesday (or was it Monday?), I listed the next two steps in the following order:

2. Clean out any previous configurations using the make clean command. This assures that you’re compiling the kernel based on the parameters you’ve established in the first step.

3. Find and create all the dependencies for your new kernel, using the make dep command.

Once again, the delirium of traveling through nine time zones got the best of me. These steps are reversed from the order they should be in. In other words, you’ll first make dep then make clean. I’m starting to think it’s a good thing I won’t be traveling again for a few weeks.

The make dep command is executed, as with the others, from the /usr/src/linux directory, as root. This step checks to make sure that all the dependencies in your new kernel, such as include files, are in place.

The make clean command is especially important if you’ve previously compiled a kernel for your system. The command assures that object files left over from that previous compilation are cleaned out, in effect purifying your current kernel configuration. In any case, it’s always a good idea to execute this command, regardless of whether you’ve previously compiled a new kernel or not.

Now, it’s on to the task that requires the most horsepower from your machine:

4. Build the actual kernel image using the make bzImage command.

The bzImage file is the image of your kernel that will be used to run the system. “bz” is a compression scheme, designed to reduce to size of the kernel such that it may be copied to and booted from a floppy. That’s right - in most cases, the core code of your Linux system can be booted from a floppy.

As your kernel is compiling, you’ll see each instruction to the compiler scroll past. If you’ve got lots of RAM and a fast processor, this task shouldn’t take too long. If, on the other hand, you’re running on an old machine, go ahead and have dinner. It might take awhile.

Tomorrow, we’ll talk about what to do with this wonderful new kernel you’ve compiled on your own.