On 15 November 2012 10:04, Lee Jones [off-list ref] wrote:

The overhead is very low and the results will be found under
sysfs/bootime, as well as detailed results in debugfs under
boottime/. The bootgraph* files are compatible with
scripts/bootgraph.pl. The reason for this patch is to provide
data (sysfs/boottime) suitable for automatic test-cases as
well as help for developers to reduce the boot time (debugfs).

Based heavily on the original driver by Jonas Aaberg.

+
+static LIST_HEAD(boottime_list);
+static DEFINE_SPINLOCK(boottime_list_lock);
+static struct boottime_timer boottime_timer;
+static int num_const_boottime_list;
+static struct boottime_list const_boottime_list[NUM_STATIC_BOOTTIME_ENTRIES];
+static unsigned long time_kernel_done;
+static unsigned long time_bootloader_done;
+static bool system_up;
+static bool boottime_done;
+
+int __attribute__((weak)) boottime_arch_startup(void)
+{
+       return 0;
+}
+
+int __attribute__((weak)) boottime_bootloader_idle(void)
+{
+       return 0;
+}

You may wish to use the __weak macro (include/linux/compiler*) instead
of directly using GCC attributes here.

Andrew Murray