BIOS supports two modes: Legacy BIOS and UEFI BIOS. You can set the UEFI BIOS Boot Mode using the Boot Menu in the BIOS Setup Utility. UEFI BIOS Boot Mode selection depends on the operating system type and configuration that is installed in the system. Some devices and operating systems do not yet support UEFI-based BIOS and can only boot from Legacy BIOS. Depending on your situation, you might have to specify which mode of BIOS you want to use, Legacy BIOS Mode or UEFI Boot Mode.
Choose Legacy BIOS Mode to allow host bus adapters (HBAs) to use Option ROMs. Choose UEFI Boot Mode to use UEFI drivers.
When using operating systems that support booting only from Legacy BIOS, the Legacy Boot Mode must be used. When using operating systems that support booting from Legacy BIOS or UEFI BIOS, either mode can be used. However, once a mode is chosen, and an operating system is installed, the installation can be booted only using the same mode that was used for the installation.
Oracle Linux 5.x
Red Hat Enterprise Linux 5.x
Oracle VM 3.0 and 3.1
For updates to this list, refer to the Sun Server X3-2L Product Notes at: http://www.oracle.com/pls/topic/lookup?ctx=SunServerX3-2L.
Only devices that support the selected mode are listed on the BIOS Boot screen. If you select UEFI Boot Mode, only boot candidates that support UEFI BIOS are listed in the Boot Options Priority list. If you select Legacy BIOS Mode, only boot candidates that support Legacy BIOS are listed in the Boot Options Priority list.
When an operating system is installed using Legacy BIOS Mode, the operating system can be booted only in Legacy BIOS Mode.
When an operating system is installed using UEFI Boot Mode, the operating system can be booted only in UEFI Boot Mode.