diff --git a/src/Config b/src/Config
index 2fc9683c..9ac46c2e 100644
--- a/src/Config
+++ b/src/Config
@@ -221,18 +221,6 @@
 #			which saves power while waiting for user interaction.
 #			Good for compute clusters and VMware emulation.
 #			But may not work for all CPUs.
-#	-DBUILD_SERIAL
-#			Include an auto-incrementing build number in
-#			the Etherboot welcome message.  Useful when
-#			developing, to be sure that the file you
-#			compiled is the one you're currently testing.
-#	-DBUILD_ID
-#			Include a build ID string in the Etherboot
-#			welcome message.  Useful when developing, if
-#			you have multiple builds with different
-#			configurations and want to check you're
-#			running the one you think you are.  Requires
-#			-DBUILD_SERIAL.
 #
 # @/OptionDescription@
 
@@ -365,12 +353,6 @@ CFLAGS+=	-DPXE_IMAGE -DPXE_EXPORT
 # via pxeboot, use only with DOWNLOAD_PROTO_NFS
 # CFLAGS+=	-DFREEBSD_PXEEMU
 
-# Include an auto-incrementing build serial number and optional build
-# ID string
-# CFLAGS+=	-DBUILD_SERIAL
-# CFLAGS+=	-DBUILD_SERIAL -DBUILD_ID=\"testing\"
-
-
 
 
 # Garbage from Makefile.main temporarily placed here until a home can
diff --git a/src/Makefile.housekeeping b/src/Makefile.housekeeping
index 1dfc34d1..dd4bd084 100644
--- a/src/Makefile.housekeeping
+++ b/src/Makefile.housekeeping
@@ -359,26 +359,24 @@ CLEANUP	+= $(NRV2B)
 # build targets to get a serial number printed at the end of the
 # build.  Enable -DBUILD_SERIAL in order to see it when the code runs.
 #
-BUILDSERIAL_H = include/.buildserial.h
+BUILDSERIAL_H		= config/.buildserial.h
+BUILDSERIAL_NOW		= config/.buildserial.now
+BUILDSERIAL_NEXT	= config/.buildserial.next
 
-$(BUILDSERIAL_H) :
-	@if [ ! -s $@ ]; then echo '#define BUILD_SERIAL_NUM 0' > $@; fi
-	@perl -pi -e 's/(BUILD_SERIAL_NUM)\s+(\d+)/"$${1} ".($${2}+1)/e' $@
+$(BUILDSERIAL_NOW) $(BUILDSERIAL_NEXT) :
+	echo 1 > $@
 
-bs : $(BUILDSERIAL_H)
-	@perl -n -e '/BUILD_SERIAL_NUM\s+(\d+)/ && ' \
-		-e 'print "Build serial number is $$1\n";' $<
+$(BUILDSERIAL_H) : $(BUILDSERIAL_NOW) $(BUILDSERIAL_NEXT)
+	echo '#define BUILD_SERIAL_NUM $(shell cat $<)' > $@
 
 ifeq ($(filter bs,$(MAKECMDGOALS)),bs)
-.PHONY : $(BUILDSERIAL_H)
+$(shell diff -q $(BUILDSERIAL_NOW) $(BUILDSERIAL_NEXT) > /dev/null || \
+	cp -f $(BUILDSERIAL_NEXT) $(BUILDSERIAL_NOW))
 endif
 
-# Ensure that include/.buildserial.h always exists, to solve the
-# problem of bootstrapping a BUILD_SERIAL-enabled build.
-#
-ifeq ($(wildcard $(BUILDSERIAL_H)),)
-$(shell $(TOUCH) $(BUILDSERIAL_H))
-endif
+bs : $(BUILDSERIAL_NOW)
+	@echo $$(( $(shell cat $<) + 1 )) > $(BUILDSERIAL_NEXT)
+	@echo "Build serial number is $(shell cat $<)"
 
 # List of available architectures
 #
diff --git a/src/config.h b/src/config.h
index 50a49457..879d0255 100644
--- a/src/config.h
+++ b/src/config.h
@@ -17,11 +17,11 @@
  *
  */
 
-#define CONSOLE_FIRMWARE	1	/* Default BIOS console */
-#define CONSOLE_SERIAL		0	/* Serial port */
-#define CONSOLE_DIRECT_VGA	0	/* Direct access to VGA card */
-#define CONSOLE_BTEXT		0	/* Who knows what this does? */
-#define CONSOLE_PC_KBD		0	/* Direct access to PC keyboard */
+#define	CONSOLE_FIRMWARE	/* Default BIOS console */
+#undef	CONSOLE_SERIAL		/* Serial port */
+#undef	CONSOLE_DIRECT_VGA	/* Direct access to VGA card */
+#undef	CONSOLE_BTEXT		/* Who knows what this does? */
+#undef	CONSOLE_PC_KBD		/* Direct access to PC keyboard */
 
 /* @END general.h */
 
@@ -35,18 +35,49 @@
  *
  */
 
-#define COMCONSOLE	0x3f8		/* I/O port address */
+#define	COMCONSOLE	0x3f8		/* I/O port address */
 
 /* Keep settings from a previous user of the serial port (e.g. lilo or
  * LinuxBIOS), ignoring COMSPEED, COMDATA, COMPARITY and COMSTOP.
  */
-#define COMPRESERVE	0
+#undef	COMPRESERVE
 
-#if ! COMPRESERVE
-#define COMSPEED	9600		/* Baud rate */
-#define COMDATA		8		/* Data bits */ 
-#define COMPARITY	0		/* Parity: 0=None, 1=Odd, 2=Even */
-#define COMSTOP		1		/* Stop bits */
+#ifdef COMPRESERVE
+#define	COMSPEED	9600		/* Baud rate */
+#define	COMDATA		8		/* Data bits */ 
+#define	COMPARITY	0		/* Parity: 0=None, 1=Odd, 2=Even */
+#define	COMSTOP		1		/* Stop bits */
 #endif
 
 /* @END serial.h */
+
+/* @BEGIN isa.h
+ *
+ * ISA probe address configuration
+ *
+ * You can override the list of addresses that will be probed by any
+ * ISA drivers.
+ *
+ */
+#undef	ISA_PROBE_ADDRS		/* e.g. 0x200, 0x300 */
+#undef	ISA_PROBE_ONLY		/* Do not probe any other addresses */
+
+/* @END isa.h */
+
+/* @BEGIN general.h
+ *
+ * Obscure configuration options
+ *
+ * You probably don't need to touch these.
+ *
+ */
+
+#define	RELOCATE		/* Relocate to high memory */
+#undef	BUILD_SERIAL		/* Include an automatic build serial
+				 * number.  Add "bs" to the list of
+				 * make targets.  For example:
+				 * "make bin/rtl8139.dsk bs" */
+#undef	BUILD_ID		/* Include a custom build ID string,
+				 * e.g "test-foo" */
+
+/* @END general.h */
diff --git a/src/core/config.c b/src/core/config.c
index ebf9d256..62ad62af 100644
--- a/src/core/config.c
+++ b/src/core/config.c
@@ -11,21 +11,46 @@
 
 #include "config/general.h"
 
+/*
+ * Build ID string calculations
+ *
+ */
+#undef XSTR
+#undef STR
+#define XSTR(s) STR(s)
+#define STR(s) #s
+
 #ifdef BUILD_SERIAL
-#include ".buildserial.h"
-#define xstr(s) str(s)
-#define str(s) #s
+#include "config/.buildserial.h"
+#define BUILD_SERIAL_STR "#" XSTR(BUILD_SERIAL_NUM)
+#else
+#define BUILD_SERIAL_STR ""
 #endif
 
-void print_config ( void ) {
-	printf( "Etherboot " VERSION
-#ifdef BUILD_SERIAL
-		" [build " 
 #ifdef BUILD_ID
-		BUILD_ID " "
+#define BUILD_ID_STR BUILD_ID
+#else
+#define BUILD_ID_STR ""
 #endif
-		"#" xstr(BUILD_SERIAL_NUM) "]"
-#endif /* BUILD_SERIAL */
+
+#if defined(BUILD_ID) && defined(BUILD_SERIAL)
+#define BUILD_SPACER " "
+#else
+#define BUILD_SPACER ""
+#endif
+
+#if defined(BUILD_ID) || defined(BUILD_SERIAL)
+#define BUILD_STRING " [build " BUILD_ID_STR BUILD_SPACER BUILD_SERIAL_STR "]"
+#else
+#define BUILD_STRING ""
+#endif
+
+/*
+ * Print out configuration
+ *
+ */
+void print_config ( void ) {
+	printf( "Etherboot " VERSION BUILD_STRING
 		" (GPL) http://etherboot.org\n"
 		"Drivers: " );
 	print_drivers();
@@ -115,30 +140,30 @@ void print_config ( void ) {
  *
  */
 
-#if	CONSOLE_DUAL
+#ifdef	CONSOLE_DUAL
 #undef	CONSOLE_FIRMWARE
 #define	CONSOLE_FIRMWARE	1
 #undef	CONSOLE_SERIAL
 #define	CONSOLE_SERIAL		1
 #endif
 
-#if CONSOLE_FIRMWARE
+#ifdef CONSOLE_FIRMWARE
 REQUIRE_OBJECT ( bios_console );
 #endif
 
-#if CONSOLE_SERIAL
+#ifdef CONSOLE_SERIAL
 REQUIRE_OBJECT ( serial );
 #endif
 
-#if CONSOLE_DIRECT_VGA
+#ifdef CONSOLE_DIRECT_VGA
 REQUIRE_OBJECT ( video_subr );
 #endif
 
-#if CONSOLE_BTEXT
+#ifdef CONSOLE_BTEXT
 REQUIRE_OBJECT ( btext );
 #endif
 
-#if CONSOLE_PC_KBD
+#ifdef CONSOLE_PC_KBD
 REQUIRE_OBJECT ( pc_kbd );
 #endif
 
@@ -147,6 +172,6 @@ REQUIRE_OBJECT ( pc_kbd );
  *
  */
 
-#if RELOCATE
+#ifdef RELOCATE
 REQUIRE_OBJECT ( relocate );
 #endif
diff --git a/src/drivers/bus/isa.c b/src/drivers/bus/isa.c
index 99784cc0..1afb1aa1 100644
--- a/src/drivers/bus/isa.c
+++ b/src/drivers/bus/isa.c
@@ -32,11 +32,21 @@ static char isa_magic[0]; /* guaranteed unique symbol */
  * User-supplied probe address list
  *
  */
-static isa_probe_addr_t isa_extra_probe_addrs[] = {
-	ISA_PROBE_ADDRS
-#if ISA_PROBE_ONLY
-	, 0
+#ifdef ISA_PROBE_ADDRS
+#  ifdef ISA_PROBE_ONLY
+#    define			HAVE_ISA_PROBE_ADDRS	1
+#    define			ISA_PROBE_ADDR_LIST	ISA_PROBE_ADDRS, 0
+#  else
+#    define			HAVE_ISA_PROBE_ADDRS	1
+#    define			ISA_PROBE_ADDR_LIST	ISA_PROBE_ADDRS
+#  endif
+#else
+#  define			HAVE_ISA_PROBE_ADDRS	0
+#  define			ISA_PROBE_ADDR_LIST	
 #endif
+
+static isa_probe_addr_t isa_extra_probe_addrs[] = {
+	ISA_PROBE_ADDR_LIST
 };
 #define isa_extra_probe_addr_count \
      ( sizeof ( isa_extra_probe_addrs ) / sizeof ( isa_extra_probe_addrs[0] ) )