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How do I check what options are compiled into a Linux kernel without looking at /boot/config-* and if I don't have access to the /boot/config-* file that's left over?

U880D
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Amandasaurus
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2 Answers2

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Unless your kernel was built with CONFIG_IKCONFIG_PROC, which would make the config available in /proc as sysadmin1138 mentioned above, you're pretty much out of luck. Debian and RH based kernel packages do, however, generally install a config-$version file in /boot. So unless it's a custom kernel, it should be available there.

Kyle Brandt
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Insyte
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I believe /proc/config.gz contains the .config file the kernel was compiled with.

sysadmin1138
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    That's only available if CONFIG_IKCONFIG_PROC was set when the kernel was built. Doesn't seem to be there by default on RHEL or Ubuntu. – Insyte Aug 06 '09 at 17:19
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    As of writing, this is enabled by default on Arch :) – Navin Apr 25 '13 at 00:33
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    to read (or grep) the current settings from config.gz you can unzip it with $cat /proc/config.gz | gunzip > mykernel.conf as suggested by Jarl on superuser.com. – xaa Oct 29 '15 at 10:59
  • It is the case on Arch Linux as CONFIG_IKCONFIG_PROC=y. – Terry Wang Jan 04 '18 at 05:11
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    @xaa Or you can use the single command alternatives zcat or zless, the latter of which is more convenient as it is a pager which allows you to scroll and search as well. – comfreak Aug 28 '19 at 18:45