Boottime is a tool which can be used for full system booting time measurement. Bootloader boot time is passed to the kernel component though ATAGS. The kernel-side driver then uses this information to provide full system boot time diagnostics though debugfs.
Aren't we converting more and more systems to use the device treee to pass information to the kenrel, with the result that ATAGS are kind of becoming extinct?
Yes, I intend to extend this functionality into Device Tree. That way it will be architecture and OS independent.
And forcing something upon a mechanism that was designed for a completely different purpose, where you see right from the first glance that it does not math easily?
Not entirely sure what you mean here. This mechanism works perfectly with ATAGs.
This makes no sense to me. Why don't you use standard mechanisms, like a shared log buffer, and simply create time-stamped entries into the kernel boot log?
The advantages should be obvious: we will need no extra kernel modification, we do not depend on ATAGS, and we are automatically architecture-independent.
Wouldn't this clog up the kernel's log buffer? I'm sure no user wants to see reams of otherwise useless logging scrawled throughout their bootlog. We'd also have a write a text parser to obtain the information for processing. It would be easier to either pass in a struct, as we do with the ATAG mechanism, or though Device Tree as previously discussed.