1 files changed, 39 insertions, 0 deletions
diff --git a/MdePkg/Library/BaseLib/Ia32/WriteCr4.c b/MdePkg/Library/BaseLib/Ia32/WriteCr4.c
new file mode 100644
index 000000000000..f14556462d3a
--- /dev/null
+++ b/MdePkg/Library/BaseLib/Ia32/WriteCr4.c
@@ -0,0 +1,39 @@
+/** @file
+  AsmWriteCr4 function
+
+  Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
+  This program and the accompanying materials
+  are licensed and made available under the terms and conditions of the BSD License
+  which accompanies this distribution.  The full text of the license may be found at
+  http://opensource.org/licenses/bsd-license.php.
+
+  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
+  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
+
+**/
+
+/**
+  Writes a value to Control Register 4 (CR4).
+
+  Writes and returns a new value to CR4. This function is only available on
+  IA-32 and x64. This writes a 32-bit value on IA-32 and a 64-bit value on x64.
+
+  @param  Value The value to write to CR4.
+
+  @return The value written to CR4.
+
+**/
+UINTN
+EFIAPI
+AsmWriteCr4 (
+  UINTN  Value
+  )
+{
+  _asm {
+    mov     eax, Value
+    _emit  0x0f  // mov  cr4, eax
+    _emit  0x22
+    _emit  0xE0
+  }
+}
+