[Techtalk] getting somewhere with this kernel.... dual kernel question...

[James]

On Sat, 11 May 2002, Conor Daly wrote:
> On Fri, May 10, 2002 at 04:02:48PM +0100 or so it is rumoured hereabouts, 
> James thought:

Hey, e-mail by telepathy! Didn't see THAT RFC coming... :-)

> > There should be a copy in the directory where you're building the kernel 
> > (assuming you've built the kernel first, then modules, then 
> > modules_install?)
> 
> More specifically, System.map is to be found in 
> /usr/src/linux-<VERSION>
> while the compressed kernel will be in
> /usr/src/linux-<VERSION>/arch/i386/boot
> but I'm sure we all know that already... :-)

Well, those of us who had kernel source to hand, anyway :-)

(I'm on a laptop, with a very full HDD - no space for kernel source...)

> Incidentally, what is the System.map

A list of the mapping between kernel address and the kernel symbols, 
needed (e.g.) for interpreting a kernel Oops message, to translate raw 
addresses into a function name and offset.

> and is it relevant to the destination
> machine when I compile a kernel on another box?

Yes; it's defined at compile time for that kernel, rather than boot time. 
(Loading modules complicates things a bit, but this is true of the kernel 
itself.) That's how Red Hat and co can ship a precompiled System.map along 
with each kernel.

> Conor (who just found out about System.map)

It's not a file you'd normally need - unless you're a kernel hacker, you 
almost certainly won't want to know about kernel address anyway!


James.