multiple kernels

cptmorgan · Posted: Sat Feb 07, 2004 9:04 pm Post subject: multiple kernels

ive always had trouble understanding and running multiple kernels....

if i make a symbolic link to /usr/src/linux/genteoo-2.6 then how does the 2.4 kernel still know how to run. also if i want to install a new kernel without genkernel and hotplugging will that matter if the 2.4 kernel uses hotplug? after installing a new kernel am i going to have to recompile everthing again or just X ?

any help would be great.... thanks

tommy_fila · Guru Joined: 19 Nov 2003 Posts: 450 Location: Phoenix, AZ

Ok, I can't answer all of your questions, but I will answer a few of them:

The link /usr/src/linux is just used so genkerel, drivers, and other kernel related programs know what kernel you are using. /usr/src/linux has nothing do to with what kernel you are actually going to boot from, it's only a symbolic link. You can have /usr/src/linux pointing to the 2.4 kernel and actually run the 2.6 kernel. However, if you want to install drivers that should be used with the 2.6 kernel, then you have to make sure the symbolic link points to the right kernel.

Usually, you don't to recompile anything with a new kernel. The only thing that needs to be recompiled are things such as video drivers, audio drivers, etc. Programs, like X, do NOT need to be recompiled.

I'm not sure about the hotplugging. I think that it is compiled with the kernel; so every kernel has its own hotplugging module. But like I said, I'm not sure.
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Ateo · Posted: Sat Feb 07, 2004 10:40 pm Post subject:

If you make a symlink to gentoo-2.6, kernel 2.4 still runs because the bzimage for 2.4 still exists in your /boot partition and that's what your bootloader uses to boot. The symlink only affects programs during compile time.

However, once you change that symlink, programs will compile using that symlink which is why you need to recompile only some drivers, such as NIC, video. X won't need to be recompiled. Hotplug shouldn't matter either in terms of being installed. However, if you're not going to enable hotplugging in the kernel, what's the point of running hotplug at boottime?

Please note, just because you create the symlink does not mean anything. It's just a symlink. After you compile your kernel and move it to /boot is when you should recompile any nic/video drivers, if applicable.

HTH.