If acpica driver is loaded using kldload(8), warn and just ignore.

sys/dev/acpica/acpi.c

@@ -162,6 +162,11 @@ acpi_identify(driver_t *driver, device_t parent)
     char		*debugpoint = getenv("debug.acpi.debugger");
 #endif
 
+    if(!cold){
+	    printf("Don't load this driver from userland!!\n");
+	    return ;
+    }
+
     /*
      * Make sure we're not being doubly invoked.
      */

sys/dev/acpica/acpi_isa.c

@@ -136,6 +136,11 @@ acpi_isa_identify(driver_t *driver, device_t bus)
     ACPI_HANDLE		parent;
     ACPI_STATUS		status;
 
+    /*If this driver is loaded from userland ,just ignore*/
+    if(!cold){
+	    return;
+    }
+
     /*
      * Look for the _SB_ scope, which will contain all the devices
      * we are likely to support.