How to get the .config from a Linux kernel image?

Question

I have a Linux kernel image in elf format and I want to find out what .config file was used to build this kernel. When I do an objdump of the image, I see a section called kernel_config_data that contains text but does not look like the config file. Is there a way to retrieve this information?

score 46 · Accepted Answer · answered Feb 19 '13 at 13:06

46

Assuming your kernel was built with the IKCONFIG option, you can use the scripts/extract-ikconfig tool to extract the original .config file.

Alternately, you can boot that kernel and find the embedded configuration in /proc/config.gz.

answered Feb 19 '13 at 13:06

Frédéric Hamidi

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And how to check if it was built w/ IKCONFIG ? I guess if ikconfig just fail : like scripts/extract-ikconfig $file extract-ikconfig: Cannot find kernel config. – RzR Jan 05 '14 at 19:35
@Frederic Hamidi I have some `.img` files which are `arm-eabi-gcc` cross compiled and I want to get the `.config` file of that images. Is it possible to do so? – GShaik Aug 25 '16 at 13:03

score 3 · Answer 2 · edited Jan 12 '22 at 10:54

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You can zcat /proc/config.gz, for example:

zcat /proc/config.gz | grep 'CONFIG_PRINTK_TIME'

To dump this into the .config used in the kernel build process:

zcat /proc/config.gz > .config

edited Jan 12 '22 at 10:54

AStopher

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answered Jul 07 '17 at 11:21

a.saurabh

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How to get the .config from a Linux kernel image?

2 Answers2