What exactly is system.map for?

[TheMuso]

I know it is generated when compiling the kernel, and booting, but why is it needed when booting from hd but not from a boot disk?

[PLBlaze]

I'm no kernel guru in any way :D but to put it simple System.map contains all the kernel symbols that get compiled in your kernel...it's also needed for proper operation of modules and can supply degugging information when kernel does Oops on you...you can run ksysms to get the debug symbols in case of oops.And yes it get's loaded no matter if you boot your kernel from hdardisk or boot floppy.Here what it says when i boot mine from floppy:

Aug 6 09:48:01 blaze kernel: Inspecting /boot/System.map
Aug 6 09:48:01 blaze kernel: Loaded 17701 symbols from /boot/System.map.
Aug 6 09:48:01 blaze kernel: Symbols match kernel version 2.4.7.

Hope this helps.