[plug] Kernel compile

[Tony Breeds]

On Wed, Mar 05, 2003 at 12:00:51AM +0800, J Michael Gilks wrote:

> I have just compiled my first kernel, and as always there is a hitch.
> The kernel is 2.4.19-24mdkcustom which is Mandrakes latest offering.
> The problem is that I installed the RPM for the kernel which installed nicely 
> and seems to work. This put a System.map file in /boot.
> I compiled a new kernel from the source, did make dep, make clean make 
> bzImage, make modules, make modules_install.

If you're on a sinngle CPU system you can do:
make bzImage modules modules_install, then get a coffee.  If anything
goes wrong at all at any stage the build will stop so you're safe in
that regard.

Then make install modules_install.

> All going swimmingly until I come to install the new image. When I try 
> cp System.map /boot
> I am asked if I want to overwrite System.map.
> This is where I bailed.
> My question is, will overwriting System .map lose the 2.4.19-24 kernel I 
> already have? If this will happen, what can I do to keep both versions?

Yes you can keep both versions.  you should be able to "make install"
have a look at /sbin/installkernel.
If you look at /boot/System.map you _should_ see that it's a symlink to
System.map-INSTALLED_VERSION.

If you overwrite it nothing bad will happen.
 
> Further questions I probably should have asked before starting are
> 1: After running depmod -a, will old dependencies be wiped out if not needed 
> for the new kernel?

Running depmod -a will rebuild the module dependancies for the currently
running system.  You can build the modules dependancies for a non runing
kernel with
depmod -ae -F /path/to/System.map  where System.mnap is the symbol table
for the kernel you want to build module dependancies for.

> 2: How do you uninstall a kernel?

If you installed it as an RPM then,
a) boot into another kernel
b) rpm -e rpmname
If you instlled it from source then
rm -rf /boot/*VERSION /lib/modules/VERSION

Yours Tony