Grabbing the current kernel config

telex4 · l33t Joined: 21 Sep 2002 Posts: 704 Location: Reading, UK

Hey, I don't need to do this but I'm asking because I'm sure someone will know, and I was trying to remember it this afternoon. When you're configuring your kernel, is there a command you can use that grabs the configuration of the kernel that's currently residing in your memory (i.e. is "running") and dump it to a config file, so you can configure a new set of sources more easily? I swear I read about it somewhere, but now I can't find anything about it!

Jimbow · Posted: Fri Apr 11, 2003 6:09 pm Post subject:

If you are running a recent kernel (might need a kernel option set too) then "cat /proc/config" does what you want.
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telex4 · l33t Joined: 21 Sep 2002 Posts: 704 Location: Reading, UK

Hmm, I don't think that was it, but thanks anyway

telex4 · l33t Joined: 21 Sep 2002 Posts: 704 Location: Reading, UK

Whilst looking through kernel stuff before trying the 2.5 series, I came across:

make oldconfig

which appears to make a .config based on the kernel that is currently running. I'm going to try it out - can anyone else shed any more light on this command?

EDIT: just tried it, and it seems to do what I said, prompting you with the "make config" style configuration choices for new/changed options in the new sources. A little hairy given that I usually use menuonfig, but I'll see if I get a good result from it

Jimbow · Posted: Sat Apr 26, 2003 11:15 pm Post subject:

I don't think "make oldconfig" does what you think. It is used for when you upgrade to a different kernel. You can't just copy .config over to the new src directory and expect it to work because kernel options change with different source releases.

To use "make oldconfig" you first copy your current .config to the new /usr/src/linux directory and then run "make oldconfig". As you say it will then prompt you with questions (usually about new kernel options that do not exist in your old .config.

If "make oldconfig" did what you think it does then there would have been no reason for them to add the option to have /proc/config in the newer kernels.
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After Perl everything else is just assembly language.

Cossins · Posted: Sat Apr 26, 2003 11:37 pm Post subject:

Just a thought:
make oldconfig could be reading the old configuration from /proc/config...