Corvalent Q35SBC, User Manual, Page: 56 / 61

Checkpoint Description
8C Late POST initialization of chipset registers.
8D Build ACPI tables (if ACPI is supported)
8E Program the peripheral parameters. Enable/Disable NMI as selected
90 Initialization of system management interrupts by invoking all handlers. Please note this
checkpoint comes right after checkpoint 20h
A1 Clean-up work needed before booting to OS.
A2 Takes care of runtime image preparation for different BIOS modules. Fill the free area in
F000h segment with 0FFh. Initializes the Microsoft IRQ Routing Table. Prepares the
runtime language module. Disables the system configuration display if needed.
A4 Initialize runtime language module. Display boot option popup menu.
A7 Displays the system configuration screen if enabled. Initialize the CPU’s before boot,
which includes the programming of the MTRR’s.
A9 Wait for user input at config display if needed.
AA Uninstall POST INT1Ch vector and INT09h vector.
AB Prepare BBS for Int 19 boot. Init MP tables.
AC End of POST initialization of chipset registers. De-initializes the ADM module.
B1 Save system context for ACPI. Prepare CPU for OS boot including final MTRR values.
00 Passes control to OS Loader (typically INT19h).
Table B-4 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:
Checkpoint Code 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.
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