Unknown Additional Driver: Processor microcode firmware for Intel CPUs for intel-microcode
The microcode data file for Linux contains the latest microcode definitions for all Intel processors.
Intel releases microcode updates to correct processor behavior as documented in the respective processor specification updates.
While the regular approach to getting this microcode update is via a BIOS upgrade, Intel realizes that this is an administrative hassle.
The Linux Operating System has a mechanism to update the microcode after booting the OS.
In Ubuntu Vivid Vervet 15.04,ubuntu-drivers-common is a framework to detect hardware-dependent components on user's machine.