[SeaBIOS] [PATCH] acpi: add xsdt support

[Gerd Hoffmann]

In case a xsdt table is present (and located below 4G)
prefer it over rsdt.

Signed-off-by: Gerd Hoffmann 
---
 src/std/acpi.h      | 11 +++++++++++
 src/fw/biostables.c | 40 ++++++++++++++++++++++++++++++----------
 2 files changed, 41 insertions(+), 10 deletions(-)

diff --git a/src/std/acpi.h b/src/std/acpi.h
index c01fa7be827c..81c22757f50e 100644
--- a/src/std/acpi.h
+++ b/src/std/acpi.h
@@ -132,6 +132,17 @@ struct rsdt_descriptor_rev1
     /* ACPI tables */
 } PACKED;

+/*
+ * ACPI 2.0 eXtended System Description Table (XSDT)
+ */
+#define XSDT_SIGNATURE 0x54445358 // XSDT
+struct xsdt_descriptor_rev2
+{
+    ACPI_TABLE_HEADER_DEF       /* ACPI common table header */
+    u64 table_offset_entry[0];  /* Array of pointers to other */
+    /* ACPI tables */
+} PACKED;
+
 /*
  * ACPI 1.0 Firmware ACPI Control Structure (FACS)
  */
diff --git a/src/fw/biostables.c b/src/fw/biostables.c
index fe8626efc05d..0d4fdb9c22e8 100644
--- a/src/fw/biostables.c
+++ b/src/fw/biostables.c
@@ -141,18 +141,38 @@ find_acpi_table(u32 signature)
     if (!RsdpAddr || RsdpAddr->signature != RSDP_SIGNATURE)
         return NULL;
     struct rsdt_descriptor_rev1 *rsdt = (void*)RsdpAddr->rsdt_physical_address;
+    struct xsdt_descriptor_rev2 *xsdt =
+        RsdpAddr->xsdt_physical_address >= 0x100000000
+        ? NULL : (void*)(u32)(RsdpAddr->xsdt_physical_address);
     dprintf(4, "rsdt=%p\n", rsdt);
-    if (!rsdt || rsdt->signature != RSDT_SIGNATURE)
-        return NULL;
-    void *end = (void*)rsdt + rsdt->length;
-    int i;
-    for (i=0; (void*)&rsdt->table_offset_entry[i] < end; i++) {
-        struct acpi_table_header *tbl = (void*)rsdt->table_offset_entry[i];
-        if (!tbl || tbl->signature != signature)
-            continue;
-        dprintf(4, "table(%x)=%p\n", signature, tbl);
-        return tbl;
+    dprintf(4, "xsdt=%p\n", xsdt);
+
+    if (xsdt && xsdt->signature == XSDT_SIGNATURE) {
+        void *end = (void*)xsdt + xsdt->length;
+        int i;
+        for (i=0; (void*)&xsdt->table_offset_entry[i] < end; i++) {
+            if (xsdt->table_offset_entry[i] >= 0x100000000)
+                continue; /* above 4G */
+            struct acpi_table_header *tbl = (void*)(u32)xsdt->table_offset_entry[i];
+            if (!tbl || tbl->signature != signature)
+                continue;
+            dprintf(1, "table(%x)=%p (via xsdt)\n", signature, tbl);
+            return tbl;
+        }
     }
+
+    if (rsdt && rsdt->signature == RSDT_SIGNATURE) {
+        void *end = (void*)rsdt + rsdt->length;
+        int i;
+        for (i=0; (void*)&rsdt->table_offset_entry[i] < end; i++) {
+            struct acpi_table_header *tbl = (void*)rsdt->table_offset_entry[i];
+            if (!tbl || tbl->signature != signature)
+                continue;
+            dprintf(1, "table(%x)=%p (via rsdt)\n", signature, tbl);
+            return tbl;
+        }
+    }
+
     dprintf(4, "no table %x found\n", signature);
     return NULL;
 }