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Chapter 4 59
DIM Code Checkpoints
The Device Initialization Manager (DIM) gets control at various times during BIOS POST to initialize different
system busses. The following table describes the main checkpoints where the DIM module is accessed.
NOTE: Checkpoints may differ between different platforms based on system configuration. Checkpoints may
change due to vendor requirements, system chipset or option ROMs from add-in PCI devices.
ACPI Runtime Checkpoints
B1 Save system context for ACPI.
00 Passes control to OS Loader (typically INT19h).
61-70 OEM POST Error. This range is reserved for chipset vendors and system
manufacturers. The error associated with this value may be different from one
platform to the next.
Checkpoint Description
2A Initialize different buses and perform the following functions: Reset, Detect, and
Disable (function 0); Static Device Initialization (function 1); Boot Output Device
Initialization (function 2). Function 0 disables all device nodes, PCI devices, and PnP
ISA cards. It also assigns PCI bus numbers. Function 1 initializes all static devices
that include manual configured onboard peripherals, memory and I/O decode windows
in PCI-PCI bridges, and noncompliant PCI devices. Static resources are also
reserved. Function 2 searches for and initializes any PnP, PCI, or AGP video devices.
38 Initialize different buses and perform the following functions: Boot Input Device
Initialization (function 3); IPL Device Initialization (function 4); General Device
Initialization (function 5). Function 3 searches for and configures PCI input devices
and detects if system has standard keyboard controller. Function 4 searches for and
configures all PnP and PCI boot devices. Function 5 configures all onboard
peripherals that are set to an automatic configuration and configures all remaining
PnP and PCI devices.
Checkpoint Description
AC First ASL check point. Indicates the system is running in ACPI mode.
AA System is running in APIC mode
01, 02, 03, 04, 05 Entering sleep state S1, S2, S3, S4, or S5.
10, 20, 30, 40, 50 Waking from sleep state S1, S2, S3, S4, or S5
Checkpoint Description