UEFI BIOS supports two boot modes: Legacy BIOS boot mode and UEFI boot mode. Some devices and operating systems do not yet support UEFI-based BIOS and can boot only from Legacy BIOS boot mode. Depending on your situation, you might have to specify which boot mode of UEFI BIOS you want to use: Legacy BIOS boot mode or UEFI boot mode. Choose Legacy BIOS boot mode to allow HBAs and Express Module devices to use option ROMs. Choose UEFI boot mode to use UEFI drivers.
Only devices that support the selected boot mode are listed on the BIOS Boot screen. If you select UEFI Boot Mode, only boot candidates that support UEFI BIOS boot mode are listed on the BIOS Setup Utility screens in the Boot Options Priority list. If you select Legacy BIOS boot mode, only boot candidates that support Legacy BIOS boot mode are listed in the Boot Options Priority list.
Note - If the boot mode is changed, the boot candidates from the previous Boot Mode disappears. Boot candidates for the newly changed Boot Mode appear after the 'Save Changes and Reset' BIOS command is issued and also appear in the screens after the next boot to BIOS Setup Utility.
When you switch between Legacy BIOS Mode and UEFI Boot Mode (in either direction), BIOS settings that affect the Boot Options Priority List settings are changed. Because the settings for a given mode do not persist on a transition between modes, you should use the ubiosconfig command to capture and preserve the BIOS configuration if you intend to switch back to the previous BIOS mode and want to retain your previous BIOS settings.
At the first release of the Sun Blade X3-2B, the following operating systems support UEFI BIOS boot mode:
Oracle Enterprise Linux
SUSE Linux Enterprise Server SP1
Red Hat Enterprise Linux
For updates to this list, refer to Sun Blade X3-2B (formerly Sun Blade X6270 M3) Product Notes.
When using operating systems that support booting only from Legacy BIOS, you must use the Legacy BIOS boot mode. When using operating systems that support booting from Legacy BIOS or UEFI BIOS, you can use either boot mode. However, once a boot mode is chosen, and an operating system is installed, the installation can be started only using the same mode that was used for the installation.
When an operating system is installed using Legacy BIOS boot mode, the operating system can be started only in Legacy BIOS boot mode.
When an operating system is installed using UEFI boot mode, the operating system can be started only in UEFI boot mode.