UefiCpuPkg/ResetVector:Add Option to reserve 4K region at 4GB

[mirror_edk2.git] / UefiCpuPkg / ResetVector / Vtf0 / Ia16 / ResetVectorVtf0.asm

diff --git a/UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm b/UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm
index 7538192876c8dedc9fa9f647750c128d48f40f1c..fe5bbea8033aa419f6e9fd1b7c57abcd9aff2d18 100644 (file)
--- a/UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm
+++ b/UefiCpuPkg/ResetVector/Vtf0/Ia16/ResetVectorVtf0.asm
@@ -21,7 +21,15 @@ ALIGN   16
 ; located just below 0x100000000 (4GB) in the firmware device.\r
 ;\r
 %ifdef ALIGN_TOP_TO_4K_FOR_PAGING\r
-    TIMES (0x1000 - ($ - EndOfPageTables) - 0x20) DB 0\r
+    TIMES (0x1000 - ($ - EndOfPageTables)) DB 0\r
+;\r
+; Pad the VTF0 Reset code for Bsp & Ap to 4k aligned block.\r
+; Some implementations may need to keep the initial Reset code\r
+; to be separated out from rest of the code.\r
+; This padding will make sure lower 4K region below 4 GB may\r
+; only contains few jmp instructions and data.\r
+;\r
+    TIMES (0x1000 - 0x20) DB 0\r
 %endif\r
 \r
 applicationProcessorEntryPoint:\r