Differences between BIOS and UEFI Boot Modes
The following table highlights the differences between the boot modes.
Feature
Operating System Support Compatible with operating systems
BIOS POST <F11> Boot
Manager Hot Key
Boot Order Control
USB Emulation
Default Boot Order
Boot Options
UEFI Boot Options
The way boot options work in UEFI mode differs from that of the legacy BIOS. The UEFI boot option:
Specifies a file on a drive as a boot target (vs. a drive as in legacy BIOS).
Is automatically created by the operating system during installation and points to its boot file.
Provides a predetermined boot path for removable media.
Can be manually added by the user via the UEFI Boot Manager.
Points to a specific boot file; hence a system format is not necessary to make a device bootable.
Automatic and Manual Boot Options
In UEFI mode, boot options are automatically added for removable devices. These automatically added boot
options cannot be deleted. Operating System installation automatically adds a boot option that points to the
Operating System Boot loader. Boot options can also be added manually by using the UEFI Boot Manager. Whether
options are added manually or by the operating system, they can be deleted using UEFI Boot Manager.
Multiple boot options per device, or per file, are allowed. You may want to have two boot options for the same
file with different input parameters, such as a debug parameter. When installing a UEFI‐aware operating system,
the installation process will add a corresponding boot option.
BIOS
that do not support UEFI. All the
current and legacy operation
systems can be installed in this
boot mode.
Enters BIOS Boot Manager
Via BIOS Setup Utility
Supported via BIOS Setup Utility
Traditional Dell BIOS default boot
order
Legacy BIOS boots to a drive.
Support for multi‐boot drive
requires a boot loader.
Boot Mode
Must support UEFI
Enters UEFI Boot Manager
Via UEFI Boot Manager
Not needed
None
In UEFI mode, there is a concept of a
boot file. This allows multiple files
to be added as a boot option on a
single drive.
UEFI
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