When you compile a program that need to include kernel sources, sometimes the compile might give you an warning message like below:

 *   CONFIG_SYSFS_DEPRECATED:     should not be set. But it is.
 *   CONFIG_SYSFS_DEPRECATED_V2:     should not be set. But it is.

To fix this, you will need to recompile your kernel using menuconfig, and find

General setup -->
         [] Create deprecated sysfs layout for older userspace tools

And uncheck this option. After you save the config, you can view the /usr/src/linux/.config, and see that these two options are unset.

Then recompile your kernel and you should be good to go.

Reference:

http://buffalo.nas-central.org/wiki/HowTo_Build_Your_Own_Custom_Kernel