cExpress-EL User’s Guide
PICMG COM.0 R3.0
Page 60
Copyright © 2021 ADLINK Technology, Inc.
6.
BIOS Checkpoints, Beep Codes
A status code is a data value used to provide diagnostic information about the boot process. Progress codes are status codes that signify successful
progression to a following initialization step. Error codes signify error conditions encountered in the process of system initialization. Aptio 5.x core can
be configured to send status codes to a variety of sources. The two most commonly used types of status codes are checkpoint codes and beep codes.
Checkpoint codes are byte length data values. Checkpoints are typically output to I/O port 80h, but Aptio 5.x core can be configured to send
checkpoints to a variety of sources. Aptio 5.x core outputs checkpoints throughout the boot process to indicate the task the system is currently
executing. Checkpoints are very useful in aiding software developers or technicians in debugging problems that occur during the pre-boot process on
production hardware. Beep code is a series of short sound signals. Beep codes are typically error codes that do not occur during normal boot process.
Note
: Beep codes are not the only sounds generated during the boot process. Some firmware components may use sounds to notify user about
other events such as detection of a hot-pluggable device. These sounds are typically generated using a frequency that is different from the
frequency of the beep codes
Aptio 5.x core follows the firmware model described by the UEFI Platform Initialization Specification (PI). The PI Specification refers the following “boot
phases”, which may apply to various checkpoint and beep code descriptions:
•
Security (SEC) – initial low-level initialization
•
Pre-EFI Initialization (PEI) – memory initialization
•
Driver Execution Environment (DXE) – main hardware initialization
•
Boot Device Selection (BDS) – system setup, pre-OS user interface & selecting a bootable device (CD/DVD, HDD, USB, Network, Shell, ...)