[PATCH v3 0/5] Improvements to console timestamps

[Andrew Cooper <andrew.cooper3@citrix.com>]

This series aims to improve on the current implementation of console
timestamps in Xen.

Patch 1 is just movement of wallclock_time()s declaration to common code.

Patch 2 changes Xen's idea of when time starts, from when the BSPs TSC was 0,
to when Xen boots.

Patch 3 guesses at AP time calibration earlier during boot, so printk()s using
the new console timestamp have a real stamp, rather than 0s.

Patch 4 is the meat of the series, adding a new timestamp implementation to
printk_start_of_line().

Patch 5 comes as a intermediate suggestion, to retain the old timestamp style,
but to display milliseconds as well.


Finally, from discussion in the office, it has been suggested that the
timestamp mode/format would be better as build-time configuration rather than
boot-time configuration.  I am on the fence with this regard, but
comments/thoughts are very welcome.

~Andrew