Simple compile questions

raypen · 04-02-2006, 03:16 PM

A few compile questions

A simple question with a non-simple answer, posed numerous times
is what do I do with System.map?

I am getting ready to compile the 2.6.13 kernel from source and
I want to be sure that I can get back to my old kernel 2.4.31 should
something go wrong. My present /boot (rearranged slightly for readability) is:

lrwxrwxrwx 1 root root 21 2006-03-05 09:30 System.map -> System.map-ide-2.4.31
-rw-r--r-- 1 root root 608033 2005-06-05 22:37 System.map-ide-2.4.31
lrwxrwxrwx 1 root root 18 2006-03-05 09:30 vmlinuz -> vmlinuz-ide-2.4.31
-rw-r--r-- 1 root root 1256566 2005-06-05 22:37 vmlinuz-ide-2.4.31
lrwxrwxrwx 1 root root 17 2006-03-05 09:30 config -> config-ide-2.4.31
-rw-r--r-- 1 root root 41760 2005-06-05 22:37 config-ide-2.4.31
-rw-r--r-- 1 root root 512 2006-03-05 09:44 boot.0300
-rw-r--r-- 1 root root 512 2006-03-05 09:44 boot.0340
-rw-r--r-- 1 root root 209 2006-03-05 09:44 boot_message.txt
-rw-r--r-- 1 root root 5032 2004-05-21 02:19 diag1.img
-rw------- 1 root root 45056 2006-03-26 22:32 map
-rw-r--r-- 1 root root 1313069 2006-03-16 20:18 newlinux

You'll notice that symlinks haven't been changed from the original kernel and
the newly compiled kernel (newlinux) has no associated 'System.map' or 'config'.
This doesn't pose a problem since klogd will search the following for System.map:

1. /boot/System.map
2. /System.map
3. /usr/src/linux/System.map

Any other programs that need System.map access will presumably do the same.

However, if I compile a new 2.6.13 kernel, I will either have to copy the System.map
to /boot or change the symlink /usr/src/linux to point to /usr/src/linux-2.6.13
instead of /usr/src/linux-2.4.31 in order for klogd (& any others) to find the
2.6.13 System.map. Either way, I wish to keep my ability to load either kernel
with the applicable System.maps.

What is the best way to insure this?

1. Copy all System.maps to boot with version nos? What about symlinks?
2. Put the 2.6.13 kernel and associated System.map in another directory?
3. Something else?
Anyone know what the 'map' file is?
Do I need an initrd if I compile everything I need into the new 2.6.13?
I assume this is only needed if you load a stock 2.6.13 kernel and say
have a Reiser fs.

TIA

dopehouse · 04-02-2006, 03:32 PM

The System.map is used for debug. So if you don't want to debug your kernel, than you don't need to copy or symlink the System.map