acpi: make default DSDT optional

Since commit f7e4dd6c18ccfbaf6cd2f5eaaed2b77cabc8a406 QEMU loads its
own copy of DSDT, so let's not build in PIIX.  This makes building in
the DSDT an option, default to on (built-in).  If no one complains for a
while, we'll be able to switch it off and then maybe remove altogether.

With CONFIG_ACPI_DSDT = y
Total size: 127348  Fixed: 58892  Free: 3724 (used 97.2% of 128KiB rom)
With CONFIG_ACPI_DSDT = n
Total size: 122844  Fixed: 58884  Free: 8228 (used 93.7% of 128KiB rom)

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

2 files changed, 12 insertions, 1 deletions

diff --git a/src/Kconfig b/src/Kconfig
index 3141069..3c80132 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -387,6 +387,16 @@ menu "BIOS Tables"
         default y
         help
             Support generation of ACPI tables.
+    config ACPI_DSDT
+        bool "Include default ACPI DSDT"
+        default y
+        depends on ACPI
+        help
+            Include default DSDT ACPI table in BIOS.
+            Required for QEMU 1.3 and older.
+            This option can be disabled for QEMU 1.4 and newer
+            to save some space in the ROM file.
+            If unsure, say Y.
 endmenu
 
 source vgasrc/Kconfig
diff --git a/src/acpi.c b/src/acpi.c
index d1cb653..bc4d8ea 100644
--- a/src/acpi.c
+++ b/src/acpi.c
@@ -823,7 +823,8 @@ acpi_setup(void)
             break;
         }
     }
-    if (fadt && !fadt->dsdt) {
+
+    if (CONFIG_ACPI_DSDT && fadt && !fadt->dsdt) {
         /* default DSDT */
         void *dsdt = malloc_high(sizeof(AmlCode));
         if (!dsdt) {