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how to generate .config file from a running kernel?
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shallpion
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Joined: 29 Sep 2008
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PostPosted: Sat Dec 05, 2009 10:13 am    Post subject: how to generate .config file from a running kernel? Reply with quote

A dump question.. assume I am running a machine but I don't have the .config file from which the kernel has been compiled. Is there any way I can generate that file from the running kernel? Thanks.
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sebv
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Joined: 14 Jan 2005
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Location: Savoie (France)

PostPosted: Sat Dec 05, 2009 10:24 am    Post subject: Reply with quote

If your kernel was compiled with

Code:
CONFIG_IKCONFIG=y
CONFIG_IKCONFIG_PROC=y


you can get the config file of this kernel with

Code:
zcat /proc/config.gz


Under Gentoo you also have http://www.gentoo.org/doc/fr/genkernel.xml, but it didn't made exactly the same kernel as the one is running.
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ronmon
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PostPosted: Sat Dec 05, 2009 10:28 am    Post subject: Reply with quote

First, check for the file "/proc/config.gz". If that isn't there, look in any kernel source tree for the extract-ikconfig script.

/usr/src/linux/scripts/extract-ikconfig

That will pull the config from a bzImage.
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shallpion
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PostPosted: Sat Dec 05, 2009 11:37 am    Post subject: Reply with quote

That is very helpful. Thank you guys :)
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Cripplys
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Joined: 04 May 2011
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PostPosted: Sun Jan 20, 2013 12:20 am    Post subject: Reply with quote

Hi guys,
i tried extract-ikconfig on bzImage, but it didn't work. Script ended with this error : extract-ikconfig: Cannot find kernel config.
Could you please help me with this? I've lost previous kernel config by unmerging gentoo-sources - it was accident. :cry:
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VoidMage
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Joined: 14 Oct 2006
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PostPosted: Sun Jan 20, 2013 1:38 am    Post subject: Reply with quote

While I haven't used extract-ikconfig, I strongly suspect it works only on kernels built with CONFIG_IKCONFIG.

Also, unless I'm missing something, a simple unmerge shouldn't have removed the old config - not unless you've removed the old kernel directory too.
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Cripplys
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PostPosted: Wed Jan 23, 2013 12:10 pm    Post subject: Reply with quote

Well, I run "emerge --depclean" and it deleted the directory too. So now I'm trying the find a solution that helps me get back config from bzImage. But as i said, extract-ikconfig doesn't work...I think there must be some solution, but i don't know it. :(
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