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Date:      Wed, 24 Apr 2002 16:33:16 +0100
From:      Daniel Bye <>
Subject:   Re: Existing Kernel Options
Message-ID:  <>
In-Reply-To: <000101c1eb9d$33014a80$>
References:  <000101c1eb9d$33014a80$>

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On Wed, Apr 24, 2002 at 10:34:52PM +0800, Michael Watson wrote:
> Hi All
> I am looking to do my first kernel build, so this may be a silly question
> but hopefully somebody can help.

Excellent!  Get stuck in!  It's easy - ever tried to do a kernel rebuild
under Linux?  I only ever got one to work, and that for only 10 minutes
before locking solid.  That's why I moved to FreeBSD, almost three years
ago, and I have never regretted it.

> I don't think the kernel distributed on my CD-ROM was compiled with the same
> kernel options as in the GENERIC configuration file.  I don't want to lose
> any existing options when I build my new kernel.

I can almost guarantee that the kernel installed when you built the
system was made from the GENERIC config file.  (Provided you got an
"official" CDROM, of course...)  If your GENERIC kernel config file has 
been edited since, there will be a mismatch.

> Is there a way to find out what kernel options the existing kernel was
> compiled with?

Not sure - without the file it's hard to say.  Try this, to see if the
config file was compiled into the finished image (not the case for the
GENERIC kernel, but it may shed some light):

strings -n 3 /kernel | sed -n 's/^___//p' > MYKERNEL

Then look at MYKERNEL - if there's anything in it, that's the config
that was used to build your kernel.

Try building a kernel from the GENERIC file - if it is the same size etc
as your running kernel, you can be fairly certain it was built with the
GENERIC config.

If anyone knows how to "reverse engineer" the kernel to reconstruct the
config file, I would be interested in seeing how...


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