I have the original Slack 10.0 2.4.26 kernel, and I am thinking of trying to compile it for my machine just to tweak it and learn about it. I have read about difficulties when going up to 2.6.x, so my question is this:
Would it make sense to get a kernel from kernel.org like 2.4.27 or 2.5.x and use that? Or should I just get the exact same kernel, 2.4.26, and compile that?

I'm mainly doing this to learn, and maybe get rid of some things that are being loaded/looked for that aren't needed.

if you don't want to use 2.6, i would use 2.4.26. i could be wrong, but i think when it goes to odd numbers (2.3.x, 2.5.x) it's kind of a "beta" version, so it's better to stick with even numbered revisions, 2.2.x, 2.4.x, 2.6.x, etc. hth

You're right, uneven versions like 2.1.x 2.3.x 2..x are development versions

Yes, play with the latest 2.4 series kernel first. There won't be any messing around with header files etc.

No. The way kernel version are done is that odd numbers are development/testing versions for even numbers. The 2.5 series of kernels were used for testing out what will be put into the 2.6 series etc

You could, but it is not a big step to go to 2.4.27, so you may as well upgrade while you are doing it.

The reason why evereyone says it is so hard to upgrade to 2.6.x (which it is not) for a lot of distributions is the glibc headers.

glibc is probably the most important part of 'linux' after the kernel (of course it depends on how you define what 'linux' is). Almost every binary on a linux system relies upon it.

You need to have some of the kernel headers that glibc was compiled against in /usr/include. The problem is that most distributions symlink these to the headers in the kernel source - which Linus says is a big no-no. This is not likely to cause any problems if the kernel is in the same series as the kernel that was used to build glibc, however, if it is of a different series it most likely will cause problems.

If you look at /usr/include/asm and /usr/include/linux, you will more than likely see that they are a symlink to /usr/src/linux/include/asm-i386 and /usr/src/linux/include/linux. If you want to compile a 2.6 kernel and you have these symlinks you must remove the symlinks and copy the header files to /usr/include:

(The above assumes you are on an intel or compatible machine i.e. not a mac or something.)

You should be able to compile a 2.6 kernel with no problems now - except that the configuration files are slightly different and 2.4 confg files don't get converted that well.

IMO, play around with compiling the 2.4 kernel and then upgrade....

It's all about learning...

EDIT: You also need to compile module-init-tools if you use a 2.6 kernel. It provides the means to load and unload modules etc.

Ok that's lots of useful info, thanks! I'm not going to do the 2.6 yet, not til I know a little more of what to expect.

One more question, all of the info i've read refers to Lilo, but I use Grub. I know how to play with Grub's config files, but is there anything special that might trip me up? What I am gathering is that I need a new entry to refer to the new kernel, and edit my entry for the kernel I'm using right now... Nothing else, right?

Pretty much.

Below is my, very simple, menu.lst from my grub directory.

Sinix is my own Linux From Scratch based distribution which is on hda5 - it is also the default option
Win XP is on hda1
hda2 has the LFS used for testing before creating Sinix.

What you would probably do is have something like:

Your new kernel would be called bzImage-new and your old kernel would be just bzImage - of course you can call it what you like. Most people use bzImage-x.x.xx where the x's are the kernel version.

Hope this helps.

Yes, that's what i was hoping, that it would be just something like that.

Wish me luck!

I'm getting there...

Here is the last of my output: Looks a little ominous!
Root device is (3, 5)
Boot sector 512 bytes.
Setup is 4653 bytes.
System is 1346 kB
warning: kernel is too big for standalone boot from floppy
make[1]: Leaving directory `/usr/src/linux-2.4.27/arch/i386/boot'

Is that bad?

It just means you won't be able to make a 1440k boot floppy. I think 'makebootdisk' will do it though, since it makes a 1680k floppy.
Sounds like you could go slimmer, though. Turn off or compile as module anything you don't need for booting or mounting root.
2.4.27 mainly is the release of SATA support.
BTW 2.4.27 and other such-named kernels are not experimental. It's the SECOND digit that indicates development, like 2.5, and hopefully soon 2.7!
I'm waiting for 2.6 to get to 2.6.20 or so before I bother with that much.

I comment what slyman say about upgrading headers or glibc...

No need at all to do that in slackware, in fact it was one of the first distribution compatible with 2.6 kernel out of the box (slackware 9.1).

Not at all. That's an ok size. If you want it smaller, you can turn off math emulation and save 66k right there. But otherwise, you can continue normally with that.