As reported by Michael Larabel in Phoronix, the Raspberry Pi firmware has been changed, it now uses the Linux 4.0 kernel.
As Michael says, “For this low-cost ARM single board computers, the newer kernel is beneficial for new features, file-system improvements, and new device support like when it comes to USB peripherals and adapters.”
More information:
http://www.phoronix.com/scan.php?page=news_item&px=Raspberry-Pi-Linux-4.0
https://www.raspberrypi.org/forums/viewtopic.php?t=113753&p=778141
