Download and unpack the latest Kernel TarBall (ie from 
http://kernel.org/). Copy the .config file from the previous Kernel's directory to the fresh one. From the new directory, run make oldconfig to pick up the old configuration, then make menuconfig to change any options for the new Kernel.
To update the symlink:
ls -l /usr/src/linux rm /usr/src/linux cd /usr/src ln -s linux-version linux
DebianLinux users will want to read KernelPackageNotes for information on using make-kpkg(1) to build a Kernel Deb. If not, they can follow the same steps, using
apt-cache search kernel-source # to find out the latest version apt-get kernel-source-version
to download the latest source.
patch-2.6.17 applies against 2.6.16, so if you have 2.6.16.n, you'll have to first remove the 2.6.16.n patch.
Use ketchup, a Python utility to handle this patching for you.
A good command line for NZ users:
ketchup -G -kftp://ftp.nz.kernel.org/pub/linux/kernel -r 2.6
Only use -G if you trust the mirror!
COMPILING the kernel: - Make sure you have gcc 2.95.3 available. gcc 2.91.66 (egcs-1.1.2) may also work but is not as safe, and *gcc 2.7.2.3 is no longer supported*.
OTOH kernels since about 2.6.15 require GCC 3.x. Read the file to find the versions of compilers and other tools you need. Make sure to check the README and Documentation/Changes files to find out which version you need. Of course you always read the compile instructions for software you download, right? :)
To compile a kernel with a specific compiler, you can say eg. make CC=gcc-2.95 bzImage to make the bzImage target using the gcc-2.95 compiler. See also DistCC
LD .tmp_vmlinux1 drivers/built-in.o(.text+0xa898a): In function `splash_getraw': : undefined reference to `con2fb_map' drivers/built-in.o(.text+0xa918c): In function `splash_verbose': : undefined reference to `con2fb_map' drivers/built-in.o(.text+0xa9670): In function `splash_status': : undefined reference to `con2fb_map' drivers/built-in.o(.text+0xa97a4): In function `splash_read_proc': : undefined reference to `con2fb_map' drivers/built-in.o(.text+0xa997d): In function `splash_write_proc': : undefined reference to `con2fb_map' make: *** [.tmp_vmlinux1] Error 1
You need to have framebuffer console support compiled in. It can't be a module! Set CONFIG_FRAMEBUFFER_CONSOLE=y in the .config. NB This sounds like a one off bug that has probably been long fixed.
Starting with 2.5.51, modules have a different format. The extension has also changed from .o to .ko, for kernel object. To work with modules, you need a completely rewritten set of module tools (modprobe(8), insmod(8), lsmod(8)), collectively called module-init-tools. They can coexist with the 2.4.x-specific tools. Note, however that module-init-tools no longer reads modules.conf and instead uses a new file called modprobe.conf(5) which has a different syntax. man 5 modprobe.conf will be your friend here. It's possible to set modprobe.conf to handle modules for both 2.4.x and 2.5.x kernels, which is pretty cool if you're a dual-booter.
nVidia drivers version 1.0-6106 and up support all 2.4 and 2.6 kernels, including kernels with the new 2.6 option for 4k stacks.
These are kernel configuration files. When the kernel configuration application is run, it reads the main kernel configuration file, located in /source/dir/arch/<your architecture>/Kconfig. This main configuration file then includes other configuration files from the different subdirectories in the kernel directory tree.
Don't edit these Kconfig files directly unless you are doing KernelDevelopment. These files are driven from .config file mentioned earlier in this article.
In the 2.4 series, you could read Documentation/Configure.help to get the equivalent information.
Safe remote kernel install howto describes a strategy for testing a new kernel on a remote machine without shutting yourself out even if it doesn't work2 pages link to KernelNotes:
