Dear everyone,
In my project, I need to upgrade my Fedora core kernel. In the process, I am facing some problems in the following:

1st: Is there any difference between compiling 2.4 kernel and 2.6 kernel?

2nd: Before upgrading the kernel, is it necessary to use the patch file to compare the difference between each kernel?

3rd: If the anser of the 2nd problem is yes, then how to use the patch file?
After I type "patch -p1 < PATCHFILENAME", then the command prompt show "File to patch: ", after that, what should i do?

4th: one time, I tried to upgrade and compile 2.4 kernel in Fedora core 1, after booting, it shows "cannot mount the root", what is it mean? what problem(s) in the steps probably be the reason??

If anyone knows how to solve my problems, please give me the whole solution or leave me some hints, thankyou very much.

What do you mean by "in my project"? Is this a homework question? Not that there's anything wrong with that, but it would help if you told us. What exactly are you trying to do?

The easiest way to upgrade kernels in Fedora is to use yum. Generally you should only compile one out of curiosity, or in the unusual case where the default kernel is missing something that you need.

If you really want to compile your own, I suggest going to a kernel.org mirror and downloading the one that you want. That way you shouldn't have to apply any patches by hand.

There are differences between 2.4 and 2.6 kernels. For most hardware that is more than a couple of years old either should work. If I was you I'd use a 2.6 kernel if possible though.

As for the problem you mention in your 4th question, there are several possible causes. I've not seen the exact error message so can't be sure exactly what's causing it, but it could be that you haven't included the IDE/SATA controller driver in the kernel, or you haven't included the filesystem that the root partition is on (compiled in, not just as a module), or it could be that your grub entry is wrong.

Thank you for replying so soon.

I find that the "unable to mount root vfs" problem is not occured when I try to compiling the kernel in FC5 on my own partition. However, this problem still occur when I install and compile FC1 and FC4 using VMWare. (I don't know why, but my final year project is not using VMWare, so it does not obstruct my project.)

Thank you very much for your helpful posting.

Unable to mount root vfs means that the kernel cannot read the file-system on the root partiton.

(in /boot/grub/menu.lst on the kernel line, there should be a root=/dev/hda1 parameter ( where hda1 is tyour root partiton)

make sure the kernel has support for this file system compiled in, NOT AS A MODULE... as the module driver will be stored on this file system..

you get a chicken and the egg problem, where the driver the kernel needs to mount the root, is stored on the root... it needs to mount root in oder to load the driver it needs to mount root.

so if your root is ext3, make sure ext3 support is compiled into the kernel.

ALSO, make sure that your root= option in the grub config ( or lilo config ) is correct.

My compile kernel task is almost finish. But one things that i don't understand inside the "menuconfig".

What is the usage of modules?
What is the difference between selecting the setting and selecting it to be modules?

Thank you for your help.

If there is something that you don't need to be able to use immediately on boot, but want once you're up and running, then you should compile it as a module. Prime examples of these are sound cards and joysticks. They serve no useful function during the early stages of booting, so they don't need to be loaded.

Thank you for replying.

All of you are very helpful. Thank you.

In this time, i need to compile the kernel in 3 harddisks respectively. But now i am facing the same problem which is

kernel panic - no syncing: VFS: Unable to moung root fs on unknown-block (3, 2)

Can anyone tell me where is the wrong during configuration in the menuconfig?
Thank YOU.

It looks as though the kernel can't find your root partition. What do you mean "I need to compile the kernel in 3 harddisks respectively"? For a single Linux install, you only need to have one kernel, installed in your /boot folder or partition.