diff --git a/benchmark.h b/benchmark.h
new file mode 100644
index 0000000..089c549
--- /dev/null
+++ b/benchmark.h
@@ -0,0 +1,13 @@
+#ifndef BENCHMARK_H
+#define BENCHMARK_H
+
+/* IO ports for different exit points */
+#define LINUX_EXIT_PORT 0xf4
+#define FW_EXIT_PORT    0xf5
+
+/* Exit point values */
+#define FW_START    1
+#define LINUX_START_FWCFG 2
+#define LINUX_START_BOOT  3
+
+#endif
diff --git a/fw_cfg.c b/fw_cfg.c
index 660c00d..f5aac73 100644
--- a/fw_cfg.c
+++ b/fw_cfg.c
@@ -7,6 +7,7 @@
 #include "bswap.h"
 #include "linuxboot.h"
 #include "multiboot.h"
+#include "benchmark.h"
 
 struct fw_cfg_file {
 	uint32_t size;
@@ -174,7 +175,7 @@
 	/* Exit just before getting to vmlinuz, so that it is easy
 	 * to time/profile the firmware.
 	 */
-	outb(0xf4, 1);
+	outb(LINUX_EXIT_PORT, LINUX_START_FWCFG);
 #endif
 
 	fw_cfg_select(FW_CFG_KERNEL_ENTRY);
diff --git a/linuxboot.c b/linuxboot.c
index 65b5936..a5f1c4f 100644
--- a/linuxboot.c
+++ b/linuxboot.c
@@ -3,6 +3,7 @@
 #include "ioport.h"
 #include "string.h"
 #include "stdio.h"
+#include "benchmark.h"
 
 static inline uint16_t lduw_p(void *p)
 {
@@ -116,7 +117,7 @@
 	/* Exit just before getting to vmlinuz, so that it is easy
 	 * to time/profile the firmware.
 	 */
-	outb(0xf4, 1);
+	outb(LINUX_EXIT_PORT, LINUX_START_BOOT);
 #endif
 	asm volatile(
 	    "ljmp $0x18, $pm16_boot_linux - 0xf0000"