On the 2.6.x kernels there are four main frontend programs: config, menuconfig, and xconfig.
config is the least user-friendly option as it merely presents a series of questions that must be answered sequentially. Alas, if an error is made you must begin the process from the top. Pressing Enter will accept the default entry which is in upper case.
oldconfig will read the defaults from an existing .config and rewrite necessary links and files. Use this option if you've made minor changes to source files or need to script the rebuild process.
menuconfig is an ncurses based frontend. Your system must have the ncurses-devel libraries installed in order to use this utility. As the help text at the top of the screen indicates, use the arrow keys to navigate the menu. Press Enter to select sub-menus. Press the highlighted letter on each option to jump directly to that option. To build an option directly into the kernel, press Y. To disable an option entirely, press N. To build an option as a loadable module, press M. You can also access content-specific help screens by pressing ? on each page or selecting HELP from the lower menu. Figure 1 in the Section called Configuring the 2.4.x kernels shows an example screen from the 2.4.x kernel series.
xconfig is a graphical frontend using qconf by Roman Zippel. It requires the qt and X libraries to build and use. The interface is intuitive and customizable. Online help is automatically shown for each kernel configuration option. It also can show dependency information for each module which can help diagnose build errors. Figure 3 shows an example of the xconfig screen. From the online help:
For each option, a blank box indicates the feature is disabled, a check
indicates it is enabled, and a dot indicates that it is to be compiled
as a module. Clicking on the box will cycle through the three states.
If you do not see an option (e.g., a device driver) that you believe
should be present, try turning on Show All Options under the Options menu.
Although there is no cross reference yet to help you figure out what other
options must be enabled to support the option you are interested in, you can
still view the help of a grayed-out option.
--qconf help
Figure 3. make xconfig
Once you have decided which configuration option to use, start the process with make followed by either config, menuconfig, or xconfig. For example:
$ make menuconfig
The system will take a few moments to build the configuration utility. Next you will be presented with the configuration menus. Though similar to the 2.4.x series, the 2.6.x menu is more logically organized with better grouping of sub-modules. Following are some of the top level configuration options in the 2.6 kernel.
Code Maturity Level Options
This option allows configuration of alpha-quality software or obsoleted drivers. It is best to disable this option if the kernel is intended for a stable production system. If you require an experimental feature in the kernel, such as a driver for new hardware, then enable this option but be aware that it "may not meet the normal level of reliability" as more rigorously tested code.
General Setup
This section contains options for sysctl support, a feature allowing run-time configuration of the kernel. A new feature, kernel .config support, allows the complete kernel configuration to be viewed during run-time. This addresses many requests to be able to see what features were compiled into the kernel.
Loadable Module Support
You will almost certainly want to enable module support. If you will need third-party kernel modules you will also need to enable Set Version Information on All Module Symbols.
Processor Type and Features
This is perhaps the most important configuration choice. we determin our processor type by examining /proc/cpuinfo and we use that information here to select the appropriate processor. Included in this submenu are features such as Preemptible Kernel which can improve desktop responsiveness, Symmetric Multi-processing Support for machines with multiple CPUs, and High Memory Support for machines with more than 1G of RAM.
Power Management Options
Found here are options for ACPI and CPU Frequency Scaling which can dramatically improve laptop power usage. Read the Documentation/power file for more information.
Bus Options ( PCI, PCMCIA, EISA, MCA, ISA)
Here are found options for all system bus devices. On modern machines the ISA and MCA support can often be disabled.
Executable File Formats
Interesting features here include the kernel support for miscellaneous binaries, which can allow seamless operation of non-Linux binaries with a little userland help.
Device Drivers
All the device-driver configuration options that were previously scattered throughout the 2.4.x menus are now neatly organized under this option. Features such as SCSI support, graphic card optimizations, sound, USB and other hardware are configured here.
File Systems
Found here are options for filesystems which are supported by the kernel, such as EXT2 and ReiserFS. It is best to build support for the root filesystems directly into the kernel rather than as a module.
Security Options
Interesting options here include support for NSA Security Enhanced Linux and other, somewhat experimental, features to increase security.
No comments:
Post a Comment