[svlug] AX.25 and the kernel

Rafael Skodlar raffi at linwin.com
Sun Aug 17 14:20:16 PDT 2003

Hi Karl,

On Sun, Aug 17, 2003 at 02:55:21PM -0600, Karl Larsen wrote:
> 	I am going to get "newqpsk" working in my Red Hat ver 8 Linux. We think
> this will be a good Amateur Radio High Frequency communications system
> for Homeland Defense use. 

Cool. TX related links over here ;-)

> 	I must get the ax.25 kernel support compiled as modules on my kernel. I
> have the usual RH8 kernel and I installed the full kernel tree so I can
> re-compile the kernel if desired.
> 	There are about 10 versions of configuration files available. I'm not
> sure which kernel I have now. It might be the i686 version since I have
> a pentium 4 cpu. 

uname -a
should tell you.

> 	What I want to do is get the modules for ax.25 support into the current
> location with the least amount of change in performance of everything
> else.
> 	Does anyone else using RH have info on an easy way to accomplish this?

I'm not in front of Redhat box right now so it's hard to say that the
following will work in your situation but it's very close.

I'm running Xandros, a (very good) Debian based distribution and am
pleased with it.

Under /lib/modules/2.4.19-x1/kernel/net/ I see 

8021q  bluetooth  ipv4  ipx   khttpd  netlink  packet  sunrpc
ax25   bridge     ipv6  irda  lapb    netrom   rose    x25

I executed command:
insmod x25
Using /lib/modules/2.4.19-x1/kernel/net/x25/x25.o

which installed/loaded module called x25. Perhaps you can do the same
assuming generic RH has those modules compiled and installed under

Note the kernel version under /lib/modules under RH is different.

To verify that x25 module is installed execute:


Module                  Size  Used by    Tainted: P
x25                    25808   0  (unused)

If you want to staticaly compile into the kernel then you need to
configure the kernel. At least 4 methods are possible:
vi .config (or use any other text editor)
make config
make menuconfig
make xconfig

If you compile your own kernel, you can still do it as a module and do
make modules_install. That will only add newly compiled modules to the
existing pool of modules if not there already. Your kernel would stay
the same otherwise. You need to add x25 to /etc/modules.conf also.

There is more to the kernel compilation and installation which is better
described elsewhere on the internet; http://www.kernel.org is a good
start. In general check /usr/src/linux/README file for quick kernel
related instructions.

Make sure your /usr partition has plenty of space since the source code
for the kernel 2.4.19 is 145684480, that's before the compiling!

In any case, keep the old kernel around in case things don't work out.
That means you have to have it in your Lilo or Grub configuration for
alternative backup.

> -- 
>                - Karl Larsen k5di Las Cruces,NM Az ScQRPions -


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