MSI IM-GS45-M - Manual (Page 55)

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Bootblock Initialization Code Checkpoints
The Bootblock initialization code sets up the chipset, memory and other com-
ponents before system memory is available. The following table describes the
type of checkpoints that may occur during the bootblock initialization portion of
the BIOS:
Checkpoint Description
Before D1
Early chipset initialization is done. Early super I/O initialization is done
including RTC and keyboard controller. NMI is disabled.
D1
Perform keyboard controller BAT test. Check if waking up from power man-
agement suspend state. Save power-on CPUID value in scratch CMOS.
D0
Go to flat mode with 4GB limit and GA20 enabled. Verify the bootblock
checksum.
D2
Disable CACHE before memory detection. Execute full memory sizing
module. Verify that flat mode is enabled.
D3
If memory sizing module not executed, start memory refresh and do mem-
ory sizing in Bootblock code. Do additional chipset initialization. Re-en-
able CACHE. Verify that flat mode is enabled.
D4
Test base 512KB memory. Adjust policies and cache first 8MB. Set
stack.
D5
Bootblock code is copied from ROM to lower system memory and control
is given to it. BIOS now executes out of RAM.
D6
Both key sequence and OEM specific method is checked to determine if
BIOS recovery is forced. Main BIOS checksum is tested. If BIOS recovery
is necessary, control flows to checkpoint E0. See Bootblock Recovery
Code Checkpoints section of document for more information.
D7
Restore CPUID value back into register. The Bootblock-Runtime interface
module is moved to system memory and control is given to it. Determine
whether to execute serial flash.
D8
The Runtime module is uncompressed into memory. CPUID information
is stored in memory.
D9
Store the Uncompressed pointer for future use in PMM. Copying Main
BIOS into memory. Leaves all RAM below 1MB Read-Write including E000
and F000 shadow areas but closing SMRAM.
DA
Restore CPUID value back into register. Give control to BIOS POST (Ex-
ecutePOSTKernel). See POST Code Checkpoints section of document
for more information.