1 files changed, 62 insertions, 0 deletions
diff --git a/OvmfPkg/Csm/LegacyBiosDxe/LegacyBda.c b/OvmfPkg/Csm/LegacyBiosDxe/LegacyBda.c
new file mode 100644
index 0000000..aa6e07a
--- /dev/null
+++ b/OvmfPkg/Csm/LegacyBiosDxe/LegacyBda.c
@@ -0,0 +1,62 @@
+/** @file
+  This code fills in BDA (0x400) and EBDA (pointed to by 0x4xx)
+  information. There is support for doing initializeation before
+  Legacy16 is loaded and before a legacy boot is attempted.
+
+Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
+
+SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include "LegacyBiosInterface.h"
+
+/**
+  Fill in the standard BDA and EBDA stuff before Legacy16 load
+
+  @param  Private     Legacy BIOS Instance data
+
+  @retval EFI_SUCCESS It should always work.
+
+**/
+EFI_STATUS
+LegacyBiosInitBda (
+  IN  LEGACY_BIOS_INSTANCE    *Private
+  )
+{
+  BDA_STRUC *Bda;
+  UINT8     *Ebda;
+
+  Bda   = (BDA_STRUC *) ((UINTN) 0x400);
+  Ebda  = (UINT8 *) ((UINTN) 0x9fc00);
+
+  ACCESS_PAGE0_CODE (
+    ZeroMem (Bda, 0x100);
+    //
+    // 640k-1k for EBDA
+    //
+    Bda->MemSize        = 0x27f;
+    Bda->KeyHead        = 0x1e;
+    Bda->KeyTail        = 0x1e;
+    Bda->FloppyData     = 0x00;
+    Bda->FloppyTimeout  = 0xff;
+
+    Bda->KeyStart       = 0x001E;
+    Bda->KeyEnd         = 0x003E;
+    Bda->KeyboardStatus = 0x10;
+    Bda->Ebda           = 0x9fc0;
+
+    //
+    // Move LPT time out here and zero out LPT4 since some SCSI OPROMS
+    // use this as scratch pad (LPT4 is Reserved)
+    //
+    Bda->Lpt1_2Timeout  = 0x1414;
+    Bda->Lpt3_4Timeout  = 0x1400;
+
+  );
+
+  ZeroMem (Ebda, 0x400);
+  *Ebda = 0x01;
+
+  return EFI_SUCCESS;
+}