I want to generate images for an embedded system and automatically measure the time they took for booting (especially for different systems).
I'm using Buildroot to generate my Linux Images. I already know the methods and how to apply them, it's just the question about how to do the time measuring.
ATM for the measuring, a GPIO Pin is set in the 1st-level bootloader to "high" and the same pin is set to "low" when entering the userspace. Then with an oscilloscope the time is measured with the cursors by hand.
Now to the problem: I got some methods I'd like to be automatically implemented by choosing these in a GUI and then let the program apply them (this shouldn't be a big deal). What I'm not so sure about is to measure the boot time afterwards when the images are ready automatically.
Has anyone a nice idea for measuring the boot time?
The only thing that comes to my mind is to rely on the kernel printk times, unfortunately these measure only the kernel time.