Hi,

When I installed Lenny it showed during startup that the kernel is 2.6.25-2-686.

I updated my sources.list from Synaptic and then checked "status" which gave some results under labels--installed, installed (auto removable)...you know them. I selected "installed (upgradeable)" and marked them all for upgrading and clicked apply.

It upgraded fine except three items due to some errors.

When I rebooted in Windows, the Grub menu came up with six options instead of the previous four! The new options were
and This apparently frightened me--I was worried if my system was ok. Well, to my relief, I'm now writing from my Debian system.

But, was it any sort of downgrading? I dared not log in to that 2.6.25-1-686 kernel system.

You sure that wasn't 2.6.26-1-686? Page through /boot/grub/menu.lst or look again. It sounds like a perfectly normal kernel upgrade to me.

Telemachos, how should I apologise?

It is Debian GNU/Linux, kernel 2.6.26-1-686. I was so worried to see seven options on Grub and the -1-686!

But, why should Debian keep two Linux kernels active at the same time? And I should definitely log in to the upgraded system, shouldn't I?

I'm gonna do that.

Yes. And when you're certain everything is working OK, you can delete the older kernel entries from your menu.lst.

Hang on! Keep the old kernel for a while, as the new one may contain bugs (you're not on Stable, obviously) that may render it unusable/unbootable at one time. Keeping the old kernel at least gives you a workable system to fix stuff from... I still have the (ancient) 2.6.24.18 kernel from Stable available on my system, while I run 2.6.25.9 on my desktop.

Oh yeah, keep the kernels. But if you delete their entries from menu.lst, most editors make a backup file so everything is not lost if problems arise.

Thanks guys.

I haven't yet deleted the old kernel's entry from the menu.lst.

But does deleting the old kernel's entry from the menu.lst mean deleting the kernel itself from the machine? Or, does it still stay? Dutch Master says he still has the old kernel's entry in his menu.lst. Does that mean he can boot the "(ancient) 2.6.24.18 kernel"?

Yes I can. You won't actually delete the kernel by removing it's reference in the menu.lst file. For that you'd need aptitude

As Dutch Master says, you shouldn't remove the kernel right away. Test the new one thoroughly before you uninstall the old one. It's perfectly fine to have more than one kernel at a time in /boot. In fact, the only real limit is size (if /boot is on its own very small partition, you can sometimes run out of space).

As a general rule with Debian, you will not have to edit /boot/grub/menu.lst manually. When you add a kernel using any of the APT tools, the menu list gets updated automagically, and likewise when you remove a kernel using an APT tool, it's entry will be removed from the menu list automatically for you.

You would use aptitude purge linux-image-2.6<version> to remove the kernel from your system.

I ALWAYS keep the previous kernel on hand in case of emergency, then purge everything older than that.

Then I check the source directories (/usr/src) to make sure I'm not holding onto Kernel header files I no longer need..

That's great advice from you all. I'm gonna keep the old kernel.

One thing: can installing something that might be compatible with the older kernel cause problems for the newer one? I don't know if that's the way, but it just struck me there might be some sort of dependency-thing about it. I'm now logging in to the new kernel system, hence the worry.

In general, kernels are backwards compatible. Unless you have very exotic hardware, it's not really an issue.

Switching to a new kernel may force you to recompile certain kernel modules. (nVidia, ndiswrapper,) other than that you shouldn't have any issues.

I recently had to install Debian Lenny on another machine. After installation and setting up the necessary sources in the sources.list, I updated and upgraded with apt-get. But this didn't upgrade the kernel to 2.6.26-1-686 as it happened on the machine I wrote about above and remains 2.6.25-1-686.

Anybody has any speculation why?

BTW, I thought it's better to revive an old thread (one-month-old) than creating a new one since the issue is relevant.

You only get the kernel upgrade automatically if you installed a dummy kernel package, something like linux-image-2.6-686 in your case. That package exists only to make sure that you have the latest version of the -686 kernel in the 2.6 series. Depending on how you installed, you may not have that package. Try this search on both machines to compare: