acpi_builtin() can be used to check at runtime whether
the ACPI subsystem is built in a qemu-system binary.

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Ani Sinha <anisinha@redhat.com>
---
 include/hw/acpi/acpi.h | 3 +++
 hw/acpi/acpi-stub.c    | 5 +++++
 hw/acpi/core.c         | 5 +++++
 3 files changed, 13 insertions(+)

diff --git a/include/hw/acpi/acpi.h b/include/hw/acpi/acpi.h
index e0e51e85b41..d1a4fa2af84 100644
--- a/include/hw/acpi/acpi.h
+++ b/include/hw/acpi/acpi.h
@@ -150,6 +150,9 @@ struct ACPIREGS {
     Notifier wakeup;
 };
 
+/* Return whether ACPI subsystem is built in */
+bool acpi_builtin(void);
+
 /* PM_TMR */
 void acpi_pm_tmr_update(ACPIREGS *ar, bool enable);
 void acpi_pm_tmr_calc_overflow_time(ACPIREGS *ar);
diff --git a/hw/acpi/acpi-stub.c b/hw/acpi/acpi-stub.c
index e268ce9b1a9..790bf509e5d 100644
--- a/hw/acpi/acpi-stub.c
+++ b/hw/acpi/acpi-stub.c
@@ -25,3 +25,8 @@ void acpi_table_add(const QemuOpts *opts, Error **errp)
 {
     g_assert_not_reached();
 }
+
+bool acpi_builtin(void)
+{
+    return false;
+}
diff --git a/hw/acpi/core.c b/hw/acpi/core.c
index 870391ed7c8..58f8964e130 100644
--- a/hw/acpi/core.c
+++ b/hw/acpi/core.c
@@ -78,6 +78,11 @@ static void acpi_register_config(void)
 
 opts_init(acpi_register_config);
 
+bool acpi_builtin(void)
+{
+    return true;
+}
+
 static int acpi_checksum(const uint8_t *data, int len)
 {
     int sum, i;
-- 
2.47.1