[SeaBIOS] [PATCH 2/2 v2] Introduce CONFIG_ACPI_MADT to possibly prevent SeaBIOS from building MADT

[Laszlo Ersek]

This config option, when set to N, allows any qemu-built MADT to take
precedence.

Signed-off-by: Laszlo Ersek <lersek at redhat.com>
---
in v2:
- replaced primitive dynamic detection code with static config option
- 352 bytes saved in 32bit flat init when set to N (RHEL-6 gcc-4.4.7)

v2 depends on Michael's [PATCHv4] acpi: make default DSDT optional

 src/acpi.c  |    3 +++
 src/Kconfig |   14 ++++++++++++++
 2 files changed, 17 insertions(+), 0 deletions(-)

diff --git a/src/acpi.c b/src/acpi.c
index 66509b4..6ef7106 100644
--- a/src/acpi.c
+++ b/src/acpi.c
@@ -327,6 +327,9 @@ build_fadt(struct pci_device *pci)
 static void*
 build_madt(void)
 {
+    if (!CONFIG_ACPI_MADT)
+        return NULL;
+
     int madt_size = (sizeof(struct multiple_apic_table)
                      + sizeof(struct madt_processor_apic) * MaxCountCPUs
                      + sizeof(struct madt_io_apic)
diff --git a/src/Kconfig b/src/Kconfig
index 3c80132..a847e71 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -397,6 +397,20 @@ menu "BIOS Tables"
             This option can be disabled for QEMU 1.4 and newer
             to save some space in the ROM file.
             If unsure, say Y.
+    config ACPI_MADT
+        bool "Build ACPI MADT (APIC) in SeaBIOS"
+        default y
+        depends on ACPI
+        help
+            Dynamically build the ACPI MADT (APIC) table in SeaBIOS, based on
+            individual values exported by QEMU and online status of VCPUs.
+            Required for QEMU 1.4 and older.
+            This option can (and should) be disabled for QEMU 1.5 and newer as
+            QEMU prepares and exports the MADT for SeaBIOS to install.
+            (Although presence of more than one MADT (APIC) tables counts as a
+            BIOS bug, guest OSes should stick with the first instance, built by
+            SeaBIOS.)
+            If unsure, say Y.
 endmenu
 
 source vgasrc/Kconfig
-- 
1.7.1