1 files changed, 33 insertions, 0 deletions
diff --git a/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/Ia32/WriteDr4.c b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/Ia32/WriteDr4.c
new file mode 100644
index 00000000..c9f336e6
--- /dev/null
+++ b/src/VBox/Devices/EFI/Firmware/MdePkg/Library/BaseLib/Ia32/WriteDr4.c
@@ -0,0 +1,33 @@
+/** @file
+  AsmWriteDr4 function
+
+  Copyright (c) 2006 - 2008, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+/**
+  Writes a value to Debug Register 4 (DR4).
+
+  Writes and returns a new value to DR4. 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 Dr4.
+
+  @return The value written to Debug Register 4 (DR4).
+
+**/
+UINTN
+EFIAPI
+AsmWriteDr4 (
+  IN UINTN Value
+  )
+{
+  _asm {
+    mov     eax, Value
+    _emit   0x0f         // mov dr4, eax
+    _emit   0x23
+    _emit   0xe0
+  }
+}
+