Windows: add support for dumping SSDT tables

Newer Windows versions expose SSDT tables via the registry. Make sure
that AcpiDump is able to query for these tables.

Tested with 'acpidump' and 'acpidump -s' on Windows 7 (registry entries
not present, nothing to dump), Windows 8.1 and 10 (29 SSDT tables). The
number of ACPI tables was be varied using QEMU system emulation.

Reference: https://bugs.acpica.org/show_bug.cgi?id=1282
Signed-off-by: Peter Wu <peter@lekensteyn.nl>

1 files changed, 56 insertions, 12 deletions

diff --git a/source/os_specific/service_layers/oswintbl.c b/source/os_specific/service_layers/oswintbl.c
index 3fc77bf8e..7f50ed7a3 100644
--- a/source/os_specific/service_layers/oswintbl.c
+++ b/source/os_specific/service_layers/oswintbl.c
@@ -143,8 +143,8 @@ static char             KeyBuffer[LOCAL_BUFFER_SIZE];
 static char             ErrorBuffer[LOCAL_BUFFER_SIZE];
 
 /*
- * Tables supported in the Windows registry. SSDTs are not placed into
- * the registry, a limitation.
+ * Tables supported in the Windows registry. Zero or more SSDTs are assumed to
+ * follow these tables.
  */
 static char             *SupportedTables[] =
 {
@@ -154,9 +154,9 @@ static char             *SupportedTables[] =
     "FACP"
 };
 
-/* Max index for table above */
+/* Number of table names for the table above. */
 
-#define ACPI_OS_MAX_TABLE_INDEX     3
+#define ACPI_OS_NUM_TABLE_ENTRIES   4
 
 
 /******************************************************************************
@@ -243,14 +243,32 @@ AcpiOsGetTableByIndex (
     ACPI_PHYSICAL_ADDRESS   *Address)
 {
     ACPI_STATUS             Status;
+    char                    *Signature;
 
 
-    if (Index > ACPI_OS_MAX_TABLE_INDEX)
+    if (Index < ACPI_OS_NUM_TABLE_ENTRIES)
     {
-        return (AE_LIMIT);
+        Signature = SupportedTables[Index];
+        Index = 0;
+    }
+    else
+    {
+        Signature = ACPI_SIG_SSDT;
+        Index -= ACPI_OS_NUM_TABLE_ENTRIES;
+    }
+
+    Status = AcpiOsGetTableByName (Signature, Index, Table, Address);
+
+    if (ACPI_SUCCESS (Status))
+    {
+        *Instance = Index;
+    }
+    else if (Status == AE_NOT_FOUND && ACPI_COMPARE_NAME (Signature, ACPI_SIG_SSDT))
+    {
+        /* Treat SSDTs that are not found as invalid index. */
+        Status = (AE_LIMIT);
     }
 
-    Status = AcpiOsGetTableByName (SupportedTables[Index], 0, Table, Address);
     return (Status);
 }
 
@@ -297,11 +315,9 @@ AcpiOsGetTableByName (
     ACPI_STATUS             Status = AE_OK;
 
 
-    /*
-     * Windows has no SSDTs in the registry, so multiple instances are
-     * not supported.
-     */
-    if (Instance > 0)
+    /* Multiple instances are only supported for SSDT tables. */
+
+    if (Instance > 0 && !ACPI_COMPARE_NAME (Signature, ACPI_SIG_SSDT))
     {
         return (AE_LIMIT);
     }
@@ -316,6 +332,28 @@ AcpiOsGetTableByName (
             return (AE_BUFFER_OVERFLOW);
         }
 
+        /*
+         * Windows stores SSDT at SSDT, SSD1, ..., SSD9, SSDA, ..., SSDS, SSDT,
+         * SSDU, ..., SSDY. If the first (0th) and the 29th tables have the same
+         * OEM ID, Table ID and Revision, then the 29th entry will overwrite the
+         * first entry... Let's hope that we do not have that many entries.
+         */
+        if (Instance > 0 && ACPI_COMPARE_NAME (Signature, ACPI_SIG_SSDT))
+        {
+            if (Instance < 10)
+            {
+                KeyBuffer[strlen (KeyBuffer) - 1] = '0' + (char) Instance;
+            }
+            else if (Instance < 29)
+            {
+                KeyBuffer[strlen (KeyBuffer) - 1] = 'A' + (char) (Instance - 10);
+            }
+            else
+            {
+                return (AE_LIMIT);
+            }
+        }
+
         WinStatus = RegOpenKeyEx (HKEY_LOCAL_MACHINE, KeyBuffer,
             0L, KEY_READ, &Handle);
 
@@ -337,6 +375,12 @@ AcpiOsGetTableByName (
             {
                 Signature = "RSDT";
             }
+            else if (ACPI_COMPARE_NAME (Signature, ACPI_SIG_SSDT))
+            {
+                /* SSDT may not be present on older Windows versions, but it is
+                 * also possible that the index is not found. */
+                return (AE_NOT_FOUND);
+            }
             else
             {
                 fprintf (stderr,