Administrator Guide

8 : BIOS vs. UEFI | Doc ID 20444677 | June 2018
3 Features Requiring UEFI Boot Mode
As UEFI grows in popularity, modern capabilities are implemented natively for UEFI Boot Mode instead of
BIOS Boot Mode. In Dell EMC servers, the following features are available only in UEFI Boot Mode:
• UEFI Secure Boot
• Boot to Non-Volatile Memory Express (NVMe) devices
• Boot to Uniform Resource Identifier (URI)
3.1 UEFI Secure Boot
Most traditional BIOS implementations do not include mechanisms that verify the integrity of non-BIOS code
modules (such as I/O device firmware or operating system loaders). A traditional BIOS may offer protection
for the non-volatile memory where the BIOS code is stored, as well as defenses against unauthorized
configuration changes. However, these implementations vary between vendors, and risks associated with
each implementation may be difficult to assess.
UEFI defines a mechanism, named Secure Boot, which verifies the integrity of each pre-boot code module
and allows only authorized code modules to execute. Users configure a Secure Boot Policy consisting of
X.509 certificates and hash values for both authorized and unauthorized entities. The system BIOS enforces
this policy when determining whether to execute pre-boot software including I/O device firmware and
operating system loaders.
For more information on Dell’s Secure Boot implementation and configuring the Secure Boot Policy, see the
following documents:
Defining a Secure Boot Policy (Dell TechCenter)
Secure Boot Management on 14G Dell EMC PowerEdge Servers (Dell TechCenter)
3.2 Boot to Non-Volatile Memory Express (NVMe) Devices
Non-Volatile Memory Express (NVMe) refers to an interface for accessing non-volatile storage connected by
PCI Express. In Dell EMC PowerEdge servers (beginning with the 13
th
generation), the NVMe boot firmware
is developed by Dell as part of the BIOS firmware, instead of developed by individual NVMe device vendors.
Dell EMC servers support booting to NVMe devices only when the server is configured for UEFI boot mode.
3.3 Boot to Uniform Resource Identifier (URI)
A Uniform Resource Identifier (URI) is a character string that a system can use to access a file. For example,
the URI “http://mydomain.org/img/bootimage.efi” indicates that a file named “bootimage.efi” can be accessed
using Hypertext Transfer Protocol (HTTP) at mydomain.org.
The Dell EMC PowerEdge BIOS supports booting to URIs only in UEFI boot mode. The bootable URI must
use the HTTP protocol. Also, the bootable URI must refer to an .EFI image (PE/COFF format). The Boot URI
can be configured in the System Setup utility or via remote management interfaces such as RACADM.