Index: MdeModulePkg/Universal/Acpi/AcpiPlatformDxe/AcpiPlatform.c
===================================================================
--- MdeModulePkg/Universal/Acpi/AcpiPlatformDxe/AcpiPlatform.c	(revision 9332)
+++ MdeModulePkg/Universal/Acpi/AcpiPlatformDxe/AcpiPlatform.c	(working copy)
@@ -10,7 +10,7 @@
   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
-**/ 
+**/
 
 #include <PiDxe.h>
 
@@ -153,7 +153,134 @@
   Buffer[ChecksumOffset] = CalculateCheckSum8(Buffer, Size);
 }
 
+#ifdef VBOX
 
+#define ACPI_RSD_PTR      SIGNATURE_64('R', 'S', 'D', ' ', 'P', 'T', 'R', ' ')
+#define EBDA_BASE         (0x9FC0 << 4)
+
+VOID *
+FindAcpiRsdPtr (
+  VOID
+  )
+{
+  UINTN                           Address;
+  UINTN                           Index;
+
+  //
+  // First Search 0x0e0000 - 0x0fffff for RSD Ptr
+  //
+  for (Address = 0xe0000; Address < 0xfffff; Address += 0x10) {
+    if (*(UINT64 *)(Address) == ACPI_RSD_PTR) {
+      return (VOID *)Address;
+    }
+  }
+
+  //
+  // Search EBDA
+  //
+
+  Address = EBDA_BASE;
+  for (Index = 0; Index < 0x400 ; Index += 16) {
+    if (*(UINT64 *)(Address + Index) == ACPI_RSD_PTR) {
+      return (VOID *)Address;
+    }
+  }
+  return NULL;
+}
+
+VOID* FindSignature(VOID* Start, UINT32 Signature, BOOLEAN NoChecksum)
+{
+    UINT8* Ptr = (UINT8*)Start;
+    UINT32 Count = 0x10000; // 16 pages
+
+    while (Count-- > 0)
+    {
+        if (   *(UINT32*)Ptr == Signature
+            && ((EFI_ACPI_DESCRIPTION_HEADER *)Ptr)->Length <= Count
+            && (NoChecksum ||
+                CalculateCheckSum8(Ptr, ((EFI_ACPI_DESCRIPTION_HEADER *)Ptr)->Length) == 0
+                ))
+        {
+                return Ptr;
+        }
+
+        Ptr++;
+    }
+    return NULL;
+}
+
+VOID
+FillSysTablesInfo(VOID** Tables, UINT32 TablesSize)
+{
+    UINT32 Table = 0;
+    EFI_ACPI_2_0_ROOT_SYSTEM_DESCRIPTION_POINTER*  RsdPtr;
+    VOID* TablesPage;
+#define FLAG_OPTIONAL    1<<0
+#define FLAG_NO_CHECKSUM 1<<1
+    static struct {
+        UINT32 Signature;
+        UINT32 Flags;
+        CHAR8* Name;
+    } TableInfo[] = {
+        // MADT, optional
+        { SIGNATURE_32('A', 'P', 'I', 'C'),  FLAG_OPTIONAL, "MADT"},
+        // FACP (also called FADT)
+        { SIGNATURE_32('F', 'A', 'C', 'P'),  0, "FADT"},
+        // FACS, according 5.2.9 of ACPI v2. spec FACS doesn't have checksum field
+        { SIGNATURE_32('F', 'A', 'C', 'S'),  FLAG_NO_CHECKSUM, "FACS"},
+        // DSDT
+        { SIGNATURE_32('D', 'S', 'D', 'T'), 0, "DSDT"},
+        // SSDT
+        { SIGNATURE_32('S', 'S', 'D', 'T'), 0, "SSDT"},
+        // HPET
+        { SIGNATURE_32('H', 'P', 'E', 'T'), FLAG_OPTIONAL, "HPET"}
+    };
+    UINT32 Index;
+
+    RsdPtr = (EFI_ACPI_2_0_ROOT_SYSTEM_DESCRIPTION_POINTER*)FindAcpiRsdPtr();
+    ASSERT(RsdPtr != NULL);
+    TablesPage = (VOID*)(UINTN)((RsdPtr->RsdtAddress) & ~0xfff);
+
+    for (Index = 0; Index < sizeof TableInfo / sizeof TableInfo[0]; Index++)
+    {
+        VOID* Ptr = FindSignature(TablesPage, TableInfo[Index].Signature,
+                                  (BOOLEAN)((TableInfo[Index].Flags & FLAG_NO_CHECKSUM) != 0));
+        if (TableInfo[Index].Signature == SIGNATURE_32('F', 'A', 'C', 'P'))
+        {
+             // we actually have 2 FADTs, see https://xtracker.innotek.de/index.php?bug=4082
+            Ptr = FindSignature((UINT8*)Ptr+32, SIGNATURE_32('F', 'A', 'C', 'P'), FALSE);
+        }
+        if (!(TableInfo[Index].Flags & FLAG_OPTIONAL))
+             ASSERT(Ptr != NULL);
+        DEBUG ((EFI_D_ERROR, "%a: %p\n", TableInfo[Index].Name, Ptr));
+        Tables[Table++] = Ptr;
+    }
+
+#if 0
+    // RSDT
+    ASSERT(Table < TablesSize);
+    Tables[Table] = FindSignature(TablesPage, SIGNATURE_32('R', 'S', 'D', 'T'));
+    DEBUG ((EFI_D_ERROR, "RSDT: %p\n", Tables[Table]));
+    ASSERT(Tables[Table] != NULL);
+    Table++;
+
+    // XSDT
+    ASSERT(Table < TablesSize);
+    Tables[Table] = FindSignature(TablesPage, SIGNATURE_32('X', 'S', 'D', 'T'));
+    DEBUG ((EFI_D_ERROR, "XSDT: %p\n", Tables[Table]));
+    ASSERT(Tables[Table] != NULL);
+    Table++;
+#endif
+
+    DEBUG((DEBUG_INFO, "We found %d tables from %d\n", Table, TablesSize));
+    Tables[Table] = NULL;
+}
+#endif
+
+#ifdef VBOX
+#define USE_MEM_TABLES 1
+#endif
+
 /**
   Entrypoint of Acpi Platform driver.
 
@@ -174,14 +301,21 @@
 {
   EFI_STATUS                     Status;
   EFI_ACPI_TABLE_PROTOCOL        *AcpiTable;
+#if USE_MEM_TABLES
+  VOID                           *VBoxTables[10];
+#else
   EFI_FIRMWARE_VOLUME2_PROTOCOL  *FwVol;
+#endif
   INTN                           Instance;
   EFI_ACPI_COMMON_HEADER         *CurrentTable;
   UINTN                          TableHandle;
+#if !USE_MEM_TABLES
   UINT32                         FvStatus;
+#endif
   UINTN                          TableSize;
   UINTN                          Size;
 
+  Size         = 0;
   Instance     = 0;
   CurrentTable = NULL;
   TableHandle  = 0;
@@ -194,6 +327,18 @@
     return EFI_ABORTED;
   }
 
+#if USE_MEM_TABLES
+  /* VBOX already has tables prepared in memory - just reuse it */
+  FillSysTablesInfo(VBoxTables, sizeof(VBoxTables)/sizeof(VBoxTables[0]));
+  while (Status == EFI_SUCCESS) {
+      CurrentTable = (EFI_ACPI_COMMON_HEADER*)VBoxTables[Instance];
+      Status = (CurrentTable == NULL) ? EFI_NOT_FOUND : EFI_SUCCESS;
+      if (CurrentTable)
+      {
+          Size = CurrentTable->Length;
+          DEBUG ((EFI_D_ERROR, "adding %p %d\n", CurrentTable, Size));
+      }
+#else
   //
   // Locate the firmware volume protocol
   //
@@ -205,7 +350,6 @@
   // Read tables from the storage file.
   //
   while (Status == EFI_SUCCESS) {
-
     Status = FwVol->ReadSection (
                       FwVol,
                       (EFI_GUID*)FixedPcdGetPtr (PcdAcpiTableStorageFile),
@@ -215,6 +359,7 @@
                       &Size,
                       &FvStatus
                       );
+#endif
     if (!EFI_ERROR(Status)) {
       //
       // Add the table
@@ -222,6 +367,7 @@
       TableHandle = 0;
 
       TableSize = ((EFI_ACPI_DESCRIPTION_HEADER *) CurrentTable)->Length;
+      DEBUG((DEBUG_INFO, "Size:%d, TableSize:%d\n", Size, TableSize));
       ASSERT (Size >= TableSize);
 
       //
@@ -252,4 +398,3 @@
 
   return EFI_SUCCESS;
 }
-