# KC2: devfs

## yokem55

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Notice: as of kernel-2.6.13 devfs is no longer included in the kernel in favour of udev.

KC2. What is devfs? Do I really need it in my kernel? How do I enable it? 

Devfs isn't a file system in the traditional sense of the term with regard to how data is structured inside a partion.  Rather, devfs is a system that allows the kernel to automagically make relevent hardware device entries in your /dev/ directory when it initializes a driver that is either built into the kernel or when a module is loaded.  

While Gentoo can be run without devfs, you will have to manually make new device entries in the /dev/ directory on your own with the mknod or mkdev commands, which introduces some extra (and usually needless) complexity.

To enable devfs in the kernel, start by bringing up the kernel configuration screen with "make menuconfig" in your /usr/src/linux directory.  You may first have to enable experimental options support by going into the very first section "Code Maturity Level Options -->" and say yes to the option "Prompt for development and/or incomplete drivers".  Then exiting out of that section, go into the "File Systems -->" section.  Then scroll down with the down arrow key until you see the option for "/dev file system support (EXPERIMENTAL)".  Select yes to this option and the sub-option that will come up beneath it "Mount automatically at boot."  You can then exit out of this section and then either make any more changes you wish to your kernel, or simply exit out of the kernel configuration screen alltogether.  You can now build your kernel as normal, and it will have proper devfs support.

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## pjp

From the old FAQ:

Do I really need to have devfs support in my kernel?

Technically, no. However, it's highly recommended. For more information, see the Installation Guide.

How do I enable devfs?

When recompiling your kernel, turn on 'Prompt for development and/or incomplete code/drivers' under 'Code maturity level options', and then look under 'File systems' for '/dev file system support'.

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