1. Added comments to ASM files

[mirror_edk2.git] / MdePkg / Library / BaseLib / X64 / ReadDr4.asm

diff --git a/MdePkg/Library/BaseLib/X64/ReadDr4.asm b/MdePkg/Library/BaseLib/X64/ReadDr4.asm
index 97740016b3494a4ac5f7764a829d26c9105ffc0a..2bed12928b8a38a007f24ec53346893c9aa82baa 100644 (file)
--- a/MdePkg/Library/BaseLib/X64/ReadDr4.asm
+++ b/MdePkg/Library/BaseLib/X64/ReadDr4.asm
@@ -31,6 +31,10 @@
 ;   );\r
 ;------------------------------------------------------------------------------\r
 AsmReadDr4  PROC\r
+    ;\r
+    ; There's no obvious reason to access this register, since it's aliased to\r
+    ; DR7 when DE=0 or an exception generated when DE=1\r
+    ;\r
     DB      0fh, 21h, 0e0h\r
     ret\r
 AsmReadDr4  ENDP\r