Specifications

QSSC-S4R Technical Product Specification Operating System Boot, Sleep, and Wake
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19. Operating System Boot, Sleep, and Wake
19.1 Boot Device Selection
The Boot Device Selection phase is responsible for controlling the booting of the system. The boot option variables are
set by an OS during OS installation or manually added by the user through the Boot Maintenance Manager of the
Setup utility. The Boot Maintenance Manager provides the capability to make permanent changes to the boot order. It
is also possible to change the first boot option for a single boot.
19.1.1 Server Management Boot Device Control
The IPMI 2.0 Specification includes provisions for server management devices to set certain boot parameters by
setting boot flags. Among the boot flags (parameter # 5 in the IPMI specification), the BIOS checks data 1-3 for forced
boot options.
The BIOS supports forced booting from the following:
x PXE
x HDD (USB, SATA, etc.)
x USB FDD
x USB key
x CD-ROM drive
Modular server systems also use:
x Extended boot flags (parameter 126)
x Compute Module Serial Console
CMOS clear is also a supported boot flag.
On each boot, the BIOS invokes the Get System Boot Options command to determine what changes have been made
to the boot options. The BIOS takes the appropriate action and clears these settings. For more information, refer to the
EPSD Blade BIOS Extension External Product Specification.
19.1.2 USB Boot Device Reordering
In order to facilitate priority boot of various external USB boot devices and media without the need to enter the Setup
utility and reconfigure the saved Boot Options order, BIOS automatically adjusts Boot Options order for the bootable
USB devices that are.
This USB Device Reordering functionality is controlled using a Setup option “USB Boot Priority” (see Section 0 for
more information) to enable or disable it. By default, the USB Device Reordering function is enabled.
The automatic reordering of USB boot devices only occurs when a USB device is newly detected and is not found in
the previously configured boot order. When the new USB boot device is removed, the configured order of Boot Options
is restored.
If a standard boot device of the same type (hard disk, CDROM, floppy) is already present in the configured Boot
Options, then the new USB device is given priority and moved to the top of that device type boot order to boot before
other devices of the same type. However, the boot device type order is not altered. If a standard boot device of the
same type is not present in the configured Boot Options, then that type is given priority and moved to the top position in
the Boot Options order to boot the new USB device before other device types that are already configured.
As an example, if a user plugs in a bootable USB Key formatted as an FDD, and there is no other FDD device, that
USB Key will be placed first in the overall boot order. On the other hand, if a user plugs in a USB hard drive (or a USB
Key formatted as an HDD), then that USB drive will be placed first among other HDDs but may not be first overall.
The new USB device appears on the Boot Manager and Boot Option screens in the BIOS Setup. If the USB boot
device is not intended for a one-time boot and will remain in the system configuration permanently, then the boot order
including the new USB device can be configured and saved using the Setup Boot Options menu as a permanent
change to the boot order.
For security reasons, this USB boot device reordering does not occur if a User Password is installed via the Security
Configuration Screen in the Setup Utility. For more information, see Section 17.2.3.4 and Section 20.6.1.