Intel D915GAG Product Specification - Page 105

Bus Initialization Checkpoints

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Error Messages and Beep Codes Table 53. Runtime Code Uncompressed in F000 Shadow RAM (continued) Code AE B1 00 Description of POST Operation Uncompress SMBIOS module and init SMBIOS code and form the runtime SMBIOS image in shadow. Going to copy any code to specific area. Copying of code to specific area done. Going to give control to INT-19 boot loader. 4.3 Bus Initialization Checkpoints The system BIOS gives control to the different buses at several checkpoints to do various tasks. Table 54 describes the bus initialization checkpoints. Table 54. Bus Initialization Checkpoints Checkpoint 2A 38 39 95 Description Different buses init (system, static, and output devices) to start if present. Different buses init (input, IPL, and general devices) to start if present. Display different buses initialization error messages. Init of different buses optional ROMs from C800 to start. While control is inside the different bus routines, additional checkpoints are output to port 80h as WORD to identify the routines under execution. In these WORD checkpoints, the low byte of the checkpoint is the system BIOS checkpoint from which the control is passed to the different bus routines. The high byte of the checkpoint is the indication of which routine is being executed in the different buses. Table 55 describes the upper nibble of the high byte and indicates the function that is being executed. Table 55. Upper Nibble High Byte Functions Value 0 1 2 3 4 5 6 7 Description func#0, disable all devices on the bus concerned. func#1, static devices init on the bus concerned. func#2, output device init on the bus concerned. func#3, input device init on the bus concerned. func#4, IPL device init on the bus concerned. func#5, general device init on the bus concerned. func#6, error reporting for the bus concerned. func#7, add-on ROM init for all buses. 105

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Error Messages and Beep Codes
105
Table 53.
Runtime Code Uncompressed in F000 Shadow RAM
(continued)
Code
Description of POST Operation
AE
Uncompress SMBIOS module and init SMBIOS code and form the runtime SMBIOS image in
shadow.
B1
Going to copy any code to specific area.
00
Copying of code to specific area done.
Going to give control to INT-19 boot loader.
4.3
Bus Initialization Checkpoints
The system BIOS gives control to the different buses at several checkpoints to do various tasks.
Table 54 describes the bus initialization checkpoints.
Table 54.
Bus Initialization Checkpoints
Checkpoint
Description
2A
Different buses init (system, static, and output devices) to start if present.
38
Different buses init (input, IPL, and general devices) to start if present.
39
Display different buses initialization error messages.
95
Init of different buses optional ROMs from C800 to start.
While control is inside the different bus routines, additional checkpoints are output to port 80h as
WORD to identify the routines under execution.
In these WORD checkpoints, the low byte of the
checkpoint is the system BIOS checkpoint from which the control is passed to the different bus
routines.
The high byte of the checkpoint is the indication of which routine is being executed in the
different buses.
Table 55 describes the upper nibble of the high byte and indicates the function that
is being executed.
Table 55.
Upper Nibble High Byte Functions
Value
Description
0
func#0, disable all devices on the bus concerned.
1
func#1, static devices init on the bus concerned.
2
func#2, output device init on the bus concerned.
3
func#3, input device init on the bus concerned.
4
func#4, IPL device init on the bus concerned.
5
func#5, general device init on the bus concerned.
6
func#6, error reporting for the bus concerned.
7
func#7, add-on ROM init for all buses.