The disabled-by-bios check currently scans dmesg(1) for a message displayed by the kernel. This is not ideal, in that a long-running system will eventually roll the dmesg logs. The kernel should expose the disabled-by-bios flag in /proc/cpuinfo.
This manpage and the utility was written by Dustin Kirkland <firstname.lastname@example.org> for Ubuntu systems (but may be used by others). Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License, Version 3 published by the Free Software Foundation.
On Debian systems, the complete text of the GNU General Public License can be found in /usr/share/common-licenses/GPL-3.