Using a New Kernel

After you copy the kernel to /boot, you must reconfigure your boot loader to use it. Chapter 10 describes this process in detail for both the Linux Loader (LILO) and Grand Unified Boot Loader (GRUB). In brief, with either boot loader you should copy a working Linux option within the boot loader configuration file (/etc/lilo.conf or /boot/grub/menu.1st), change its name, and change the reference to the kernel file. Be sure to create a copy of a working entry and modify the copy; keep the original reference around, just as you keep the original kernel, so that you have a known-working fallback should you have problems with the new kernel. For LILO, you must then type lilo as root to install the changed configuration. In the case of GRUB, you don't need to type any special commands after modifying the configuration file.

Warning Many distributions use RAM disks as part of their normal boot process.

These configurations may include highly kernel-specific features, though, so they may not work correctly after you upgrade your kernel. Be sure to eliminate references to RAM disks from your boot loader configuration for your new kernel. You may also need to eliminate options that change the video mode. Depending on the options you chose, these features may result

This document was created by an unregistered ChmMagic, please go to to regist* in a blank screen as the system boots.

If you don't want to modify your boot loader configuration, you can test a new kernel by using LOADLIN (also described in Chapter 10) to boot your new kernel. Alternatively, you can type make bzdisk to create a boot floppy with the new kernel. In either case, you must still copy the kernel modules to their target location by typing make modules_install.

Changing a kernel is one of the few software upgrades that necessitates a reboot of a Linux system. When you reboot, pick the new kernel from the boot loader's menu and pay attention to the boot messages as your system starts up. Chances are most of these messages will scroll by too quickly for you to read, but you may notice problems—drivers that report they can't find hardware, servers that don't load, and so on. If the system boots and allows you to log in, you might want to type dmesg | less to peruse the kernel messages at a more reasonable pace; however, this command won't display the SysV startup script messages. In extreme cases, the system may freeze during the boot process. If this happens, examine the error messages for clues, then reboot the computer and choose your old kernel. You can then try to track down the source of the problem in your kernel configuration. Perhaps you omitted an important driver or set an option too optimistically.

If all goes well, you should be greeted by a working Linux system. It should function much as did your original system, but it may include a better mix of options for your system, security or bug fixes, or other desirable improvements.

Team LIB

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