Re: [v1 0/9] Early boot time stamps for x86

[Thomas Gleixner]

On Wed, 22 Mar 2017, Pasha Tatashin wrote:
> Yes, I am certain it is 0 or  near 0 on reset on this machine. Because, I

Emphasis on "this machine'

It's not guaranteed especially not on reboot and not with creative BIOSes
fiddling with the TSC_ADJUST value. 

 - It CANNOT be used to measure BIOS boot time reliably

 - If BIOS wreckaged TSC_ADJUST, then your whole time stamping goes out the
   window once the kernel sanitized it.

See other mail.

Thanks,

        tglx