[coreboot] printing TSC in printk

[Peter Stuge]

On Sat, Feb 09, 2008 at 12:50:28PM -0800, ron minnich wrote:
> Define an option
> PRINTK_TSC

This is good. Linux has the same option.


> What it does: each time printk would print a newline, it will
> instead print this:
> (16 hex digits of TSC)\n

Pro: Every line has time
Con: Time is last on the line


> Define a new format letter, T, such that %T as a format means
> "time".

Pro: Time can be first on line
Con: We need to add it manually.


Doing it like Linux would need a static variable near printk() to
keep \n state. :\


> first option allows comprehensive timing, but it will slow things
> down a bit.

This must be optional though.


> Second option allows us to completely tailor the printing of
> time, but you have to explicitly add %T when you want time
> printed.
> 
> Comments?

I think it is important that the time always is printed at the same
position in a line, but manually having to add %T to every printk is
impossible.

Maybe the answer is a macro wrapper around printk() (why is it called
print_k_ by the way, we are not the kernel) which is defined
differently depending on the config option.

If the option is set, the macro always prepends "%T " to the format
string.


//Peter