1. Add comments about reserve space on space according to x64 calling convention

[mirror_edk2.git] / MdePkg / Library / BaseLib / X64 / SwitchStack.asm

diff --git a/MdePkg/Library/BaseLib/X64/SwitchStack.asm b/MdePkg/Library/BaseLib/X64/SwitchStack.asm
index 53d1417f0b42636b68a7482b5987809407228581..380289a2d095623181afeabbb38b2ea3b73e70a6 100644 (file)
--- a/MdePkg/Library/BaseLib/X64/SwitchStack.asm
+++ b/MdePkg/Library/BaseLib/X64/SwitchStack.asm
@@ -1,6 +1,6 @@
 ;------------------------------------------------------------------------------\r
 ;\r
-; Copyright (c) 2006, Intel Corporation\r
+; Copyright (c) 2006 - 2008, 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
@@ -22,12 +22,12 @@
 ;------------------------------------------------------------------------------\r
 ; Routine Description:\r
 ;\r
-;   Routine for switching stacks with 1 parameter\r
+;   Routine for switching stacks with 2 parameters\r
 ;\r
 ; Arguments:\r
 ;\r
 ;   (rcx) EntryPoint    - Entry point with new stack.\r
-;   (rdx) Context       - Parameter for entry point.\r
+;   (rdx) Context1      - Parameter1 for entry point.\r
 ;   (r8)  Context2      - Parameter2 for entry point.\r
 ;   (r9)  NewStack      - Pointer to new stack.\r
 ;\r
@@ -40,6 +40,10 @@ InternalSwitchStack PROC
     mov     rax, rcx\r
     mov     rcx, rdx\r
     mov     rdx, r8\r
+    ;\r
+    ; Reserve space for register parameters (rcx, rdx, r8 & r9) on the stack,\r
+    ; in case the callee wishes to spill them.\r
+    ;\r
     lea     rsp, [r9 - 20h]\r
     call    rax\r
 InternalSwitchStack ENDP\r