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