Intel 253668-032US User Manual

Page of 806
9-56   Vol. 3
PROCESSOR MANAGEMENT AND INITIALIZATION
In general, each function returns with CF cleared and AH contains the returned 
status. The general return codes and other constant definitions are listed in Section 
9.11.8.9, “Return Codes.”
The OEM error field (AL) is provided for the OEM to return additional error informa-
tion specific to the platform. If the BIOS provides no additional information about the 
error, OEM error must be set to SUCCESS. The OEM error field is undefined if AH 
contains either SUCCESS (00H) or NOT_IMPLEMENTED (86H). In all other cases, it 
must be set with either SUCCESS or a value meaningful to the OEM.
The following sections describe functions provided by the INT15H-based interface.
9.11.8.5   Function 00H—Presence Test
This function verifies that the BIOS has implemented required microcode update 
functions. Table 9-13 lists the parameters and return codes for the function.
 
In order to assure that the BIOS function is present, the caller must verify the carry 
flag, the return code, and the 64-bit signature. The update count reflects the number 
of 2048-byte blocks available for storage within one non-volatile RAM.
The loader version number refers to the revision of the update loader program that is 
included in the system BIOS image.
Table 9-13.  Parameters for the Presence Test  
Input
AX
Function Code
0D042H
BL
Sub-function
00H - Presence test
Output
CF
Carry Flag
Carry Set - Failure - AH contains status
Carry Clear - All return values valid
AH
Return Code
 
AL
OEM Error
Additional OEM information.
EBX
Signature Part 1
'INTE' - Part one of the signature 
ECX
Signature Part 2
'LPEP'- Part two of the signature
EDX
Loader Version
Version number of the microcode update loader
SI
Update Count
Number of 2048 update blocks in NVRAM the BIOS 
allocated to storing microcode updates 
Return Codes (see Table 9-18 for code definitions
SUCCESS
The function completed successfully.
NOT_IMPLEMENTED
The function is not implemented.