OVMF ResetVector: Modify interface with SEC module

[mirror_edk2.git] / OvmfPkg / ResetVector / Ia32 / SearchForBfvBase.asm

diff --git a/OvmfPkg/ResetVector/Ia32/SearchForBfvBase.asm b/OvmfPkg/ResetVector/Ia32/SearchForBfvBase.asm
index e6ca6e6ffbb8825d0f25f2e49380590f2077a52e..21b64f46e37b5be97f3069d0fa698ad3621a19d0 100644 (file)
--- a/OvmfPkg/ResetVector/Ia32/SearchForBfvBase.asm
+++ b/OvmfPkg/ResetVector/Ia32/SearchForBfvBase.asm
@@ -1,6 +1,8 @@
 ;------------------------------------------------------------------------------\r
+; @file\r
+; Search for the Boot Firmware Volume (BFV) base address\r
 ;\r
-; Copyright (c) 2008, Intel Corporation\r
+; Copyright (c) 2008 - 2009, Intel Corporation\r
 ; All rights reserved. This program and the accompanying materials\r
 ; are licensed and made available under the terms and conditions of the BSD License\r
 ; which accompanies this distribution.  The full text of the license may be found at\r
@@ -9,14 +11,6 @@
 ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
 ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
 ;\r
-; Module Name:\r
-;\r
-;   SearchForBfvBase.asm\r
-;\r
-; Abstract:\r
-;\r
-;   Search for the Boot FV Base Address\r
-;\r
 ;------------------------------------------------------------------------------\r
 \r
 ;#define EFI_FIRMWARE_FILE_SYSTEM2_GUID \\r
@@ -29,21 +23,21 @@
 BITS    32\r
 \r
 ;\r
-; Input:\r
-;   None\r
+; Modified:  EAX, EBX\r
+; Preserved: EDI, ESP\r
 ;\r
-; Output:\r
-;   EBP - BFV Base Address\r
-;\r
-; Modified:\r
-;   EAX, EBX\r
+; @param[out]  EBP  Address of Boot Firmware Volume (BFV)\r
 ;\r
 Flat32SearchForBfvBase:\r
 \r
     xor     eax, eax\r
 searchingForBfvHeaderLoop:\r
+    ;\r
+    ; We check for a firmware volume at every 4KB address in the top 16MB\r
+    ; just below 4GB.  (Addresses at 0xffHHH000 where H is any hex digit.)\r
+    ;\r
     sub     eax, 0x1000\r
-    cmp     eax, 0xff800000\r
+    cmp     eax, 0xff000000\r
     jb      searchedForBfvHeaderButNotFound\r
 \r
     ;\r
@@ -70,19 +64,23 @@ searchingForBfvHeaderLoop:
     jmp     searchedForBfvHeaderAndItWasFound\r
 \r
 searchedForBfvHeaderButNotFound:\r
-    writeToSerialPort '!'\r
-    xor     eax, eax\r
+    ;\r
+    ; Hang if the SEC entry point was not found\r
+    ;\r
+    debugShowPostCode POSTCODE_BFV_NOT_FOUND\r
 \r
-searchedForBfvHeaderAndItWasFound:\r
+    ;\r
+    ; 0xbfbfbfbf in the EAX & EBP registers helps signal what failed\r
+    ; for debugging purposes.\r
+    ;\r
+    mov     eax, 0xBFBFBFBF\r
     mov     ebp, eax\r
+    jmp     $\r
 \r
-    writeToSerialPort 'B'\r
-    writeToSerialPort 'F'\r
-    writeToSerialPort 'V'\r
-    writeToSerialPort ' '\r
+searchedForBfvHeaderAndItWasFound:\r
+    mov     ebp, eax\r
 \r
-    or      ebp, ebp\r
-    jz      $\r
+    debugShowPostCode POSTCODE_BFV_FOUND\r
 \r
     OneTimeCallRet Flat32SearchForBfvBase\r
 \r