Alan J. Flavell wrote:

>On Mon, 27 Sep 2004, Brett Viren wrote:
>
>
>
>>The .config file is created when running "make config", "make
>>menuconfig" or "make xconfig" (prior to actually building the kernel).
>>
>>
>
>Sure, it *would* be - *if* I had intended building a kernel.
>
>
>
>>It needs to be there and correctly reflect how the kernel is
>>actually built for most out-of-kernel drivers to work.
>>
>>
>
>Exactly.  Which is why I'm asking whether we get the corresponding
>config file supplied when we install a pre-built SL kernel...
>
>
>
>>Some kernels store their config in /proc/config.gz,
>>
>>
>
>Thanks - I don't see anything like that on this SL installation.
>
>
I'm not sure, but isn't it a 2.6+ feature of kernels ?

>However, that prompted me to look around some more, and I found
>
>   /boot/config-2.4.21-20.EL
>
>which seems as if it's the SL answer to the earlier question.
>
>
>
>>mkdir /usr/src/linux
>>zcat /proc/config.gz > /usr/src/linux/.config
>>
>>
>
>Well, the additional kernel module that I'm playing with, has a
>Makefile which derives the running kernel version (KVERS) from
>$(shell uname -r) , and then constructs a kernel source location
>(KSRC) as /lib/modules/$(KVERS)/build i.e currently for me that's
>/lib/modules/2.4.21-20.EL/build
>
>When I check that out on SL, I find that it's a symlink to
>../../../usr/src/linux-2.4.21-20.EL   (typical hall of mirrors!)
>
>There's actually a symlink /usr/src/linux-2.4 pointing to that.
>
>But your /usr/src/linux doesn't exist - nor would this Makefile
>be looking for it even if it did.
>
>As I said before - I had actually located a whole box of config files,
>they're in  /usr/src/linux.../configs/kernel-...-.config
>
>And I had identified the appropriate one and copied it to
>/usr/src/linux-2.4/.config , and thus completed the original task.
>
>However, it now seems that this file /boot/config-2.4.21-20.EL would
>have been just as good as the starting point.
>
>
>
You should also beware of some other problems:
in most cases, you will have to put the '.config' file so that modules
can compile,
but you also have to do a 'make dep' so that many computed files are
generated.
Beware in this case that in 'Makefile' the EXTRAVERSION flag is set to
-15ELcustom! For a new module you may want to have the same kernel version
than the one running (i.e. -15EL or -15ELsmp).

In fact the way kernel sources are managed is not usefull in redhat.
For each _installed_ kernel the /lib/module/<kernel_version>/build
should point
to the full set of kernel files (.config, version, headers) that
correspond exactly to
the installed version.
And this should be totally separated from the kernel sources, as someone
may want
to build a kernel without loosing the possibility to build new modules
for the
existing one.
I often compile kernels on a machine for an other machine... After that
I always have
to rebuild properly the /usr/src/linux-2.4/ tree so that I can compile
new modules.

Maybe it should be a SL improvement for future release ?
It is not really difficult, as the only things to do are:
- remove the symlink 'build'
- create a directory with the generated headers and the .config for the
kernel
And that for each compiled kernel.

--
Yannick Perret


>cheers
>
>