HP t820 Maintenance & Service Manual page 96

more complete description of the network BIOS flashing utilities, view the DOSFlash.txt file located in
the DOS Flash folder.
BitLocker Drive Encryption / BIOS Measurements
If you have Windows BitLocker Drive Encryption (BDE) enabled on your system, we recommend that
you temporarily suspend BDE before updating the BIOS. You should also obtain your BDE recovery
password or recovery PIN before suspending BDE. After the you flash the BIOS, you can resume BDE.
To make a change to BDE, select Start > Control Panel > BitLocker Drive Encryption, click
Suspend Protectionor Resume Protectionand then click Yes.
As a general rule, updating the BIOS will modify measurement values stored in the Platform
Configuration Registers (PCRs) of the system's security module. Temporarily disable technologies that
use these PCR values to ascertain platform health (BDE is one such example) prior to flashing the BIOS.
Once you update the BIOS, re-enable the functions and restart the system so that you can take new
measurements.
BootBlock Emergency Recovery Mode
In the event of a failed BIOS update (for example if power is lost while updating), the System BIOS may
become corrupted. BootBlock Emergency Recovery Mode detects this condition and automatically
searches the root directory of the hard drive and any USB media sources for a compatible binary
image. Copy the binary (.bin) file in the DOS Flash folder to the root of the desired storage device, and
then power on the system. Once the recovery process locates the binary image, it attempts the recovery
process. The automatic recovery continues until it successfully restores or updates the BIOS. If the system
has a BIOS Setup password, you may need to use the Startup Menu / Utilities submenu to flash the
BIOS manually after providing the password. Sometimes there are restrictions on which BIOS versions
are allowed to be installed on a platform. If the BIOS that was on the system had restrictions, then only
allowable BIOS versions may be used for recovery.
88 Appendix G System BIOS