.: Advanced Linux Networking :.

Kernel compilation usually proceeds smoothly if you configured the kernel correctly, but occasionally errors pop up. Common problems include the following:

• Buggy or incompatible code— Sometimes you'll find that drivers are buggy or incompatible with other features. This is most common when you try to use a development kernel or a non-standard driver you've added to the kernel. The usual symptom is a compilation that fails with one or more error messages. The usual solution is to upgrade the kernel, or at least the affected driver, or omit it entirely if you don't really need that feature.
• Unfulfilled dependencies— If a driver relies upon some other driver, the first driver should only be selectable after the second driver has been selected. Sometimes, though, the configuration scripts miss such a detail, so you can configure a system that won't work. The most common symptom is that the individual modules compile, but they won't combine into a complete kernel file. (If the driver is compiled as a module, it may return an error message when you try to load it.) With any luck, the error message will give you some clue about what you need to add to get a working kernel. Sometimes, typing make dep and then recompiling will fix the problem. Occasionally, compiling the feature as a module rather than directly into the kernel (or vice-versa) will overcome such problems.
• Old object files— If you compile a kernel, then change the configuration and compile again, the make utility that supervises the process should detect what files may be affected by your changes and recompile them. Sometimes this doesn't work correctly, though, with the result being an inability to build a complete kernel, or sometimes a failure when compiling individual files. Typing make clean should clear out preexisting object files (the compiled versions of individual source code files), thus fixing this problem.
• Compiler errors— The GNU C Compiler (GCC) is normally reliable, but there have been incidents in which it's caused problems. Red Hat 7.0 shipped with a version of GCC that could not compile a 2.2.x kernel, but this problem has been overcome with the 2.4.x kernel series. (Red Hat 7.0 actually shipped with two versions of GCC; to compile a kernel, you had to use the kgcc program rather than gcc.)
• Hardware problems— GCC stresses a computer's hardware more than many programs, so kernel compilations sometimes turn up hardware problems. These often manifest as signal 11 errors, so called because that's the error message returned by GCC. Defective or over heated CPUs and bad RAM are two common sources of these problems. http://www.bitwizard.nl/sig11/ has additional information on this problem.

If you can't resolve a kernel compilation problem yourself, try posting a query to a Linux newsgroup, such as comp.os.linux.misc. Be sure to include information on your distribution, the kernel version you're trying to compile, and any error messages you see. (You can omit all the nonerror compilation messages.)