Running Linux, 5th Edition - Matthias Kalle Dalheimer [347]
Telephony support
Linux supports some interface cards that let you use a normal telephone set with VoIP (voice-over-IP) Internet telephony . As the documentation says, this has nothing to do with modems, so you have to enable this only if you have such an interface card.
Character devices
Linux supports a number of special "character" devices, such as serial and parallel port controllers, tape drives, and mice with their own proprietary interfaces (not mice that connect to the serial and USB ports, such as the Microsoft serial mouse) or most newer mice.
Sound
This section lets you pick between two different sound systems, the newer ALSA (Advanced Linux Sound Architecture) and the older OSS (Open Sound System). If it supports your sound hardware, go for ALSA.
USB support
Enable this to get support for many USB devices. In particular, if you want to use the popular memory sticks, you need to select USB Mass Storage Support as well. This option also applies to digital cameras that are connected to your computer via the USB port.
Filesystems
This is a series of questions for each filesystem type supported by the kernel. As discussed in the section "Managing Filesystems" in Chapter 10, a number of filesystem types are supported by the system, and you can pick and choose which to include in the kernel. Nearly all systems should include support for the Second Extended and /proc filesystems. You should include support for the MS-DOS filesystem if you want to access your MS-DOS files directly from Linux, and the ISO 9660 filesystem to access files on a CD-ROM (most of which are encoded in this way).
Kernel hacking
This section contains options that are useful only if you plan on hacking the Linux kernel yourself. If you do not want to do this, answer no.
Preparing the ground: make clean
If you wish to force a complete recompilation of the kernel, you should issue make clean at this point. This removes from this source tree all object files produced from a previous build. If you have never built the kernel from this tree, you're probably safe skipping this step (although it can't hurt to perform it). If you are tweaking minor parts of the kernel, you might want to avoid this step so that only those files that have changed will be recompiled. At any rate, running make clean simply ensures the entire kernel will be recompiled "from scratch," and if you're in any doubt, use this command to be on the safe side.
Compiling the kernel
Now you're ready to compile the kernel. This is done with the command make bzImage. It is best to build your kernel on a lightly loaded system, with most of your memory free for the compilation. If other users are accessing the system, or if you're trying to run any large applications yourself (such as the X Window System, or another compilation), the build may slow to a crawl. The key here is memory. If a system is low on memory and starts swapping, it will be slow no matter how fast the processor is.
The kernel compilation can take anywhere from a few minutes to many hours, depending on your hardware. There is a great deal of code—well over 80 MB—in the entire kernel, so this should come as no surprise. Slower systems with 16 MB (or less) of RAM can expect to take several hours for a complete rebuild; faster machines with more memory can complete it in less than half an hour. Your mileage will most assuredly vary.
If any errors or warnings occur while compiling , you cannot expect the resulting kernel to work correctly; in most cases, the build will halt if an error occurs. Such errors can be the result of incorrectly applying patches, problems