On 12/17/10, Richard Cochran [off-list ref] wrote:

This patch adds a new mode bit into the timex structure. When set, the bit
instructs the kernel to add the given time value to the current time.

The proposed new control mode, ADJ_SETOFFSET, is logically the same as
ADJ_OFFSET with timex.constant == -INFINITY.  So it is possible to do
the same thing without risking forward compatibility.  (I mean by "risking
forward compatibility" that the mode bit 0x0040 may be defined differently
by the upstream maintainer anytime in the future.)