System Resources
AMI POST Code
Bootblock Initialization Code Checkpoinits
The Bootblock initialization code sets up the chipset, memory and other components before system memory is available. The following table describes the type of check- points 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 |
| management suspend state. Save |
| CMOS. |
DO | 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 |
| memory sizing in Bootblock code. Do additional chipset initialization. |
|
|
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. |
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 |
| and F000 shadow areas but closing SMRAM. |
DA | Restore CPUID value back into register. Give control to BIOS POST |
| (ExecutePOSTKernel.) See POST Code Checkpoint list for more |
| information. |
