[poky] about 'noexec' message

[Tian, Kevin]

>From: Tian, Kevin
>Sent: Thursday, December 16, 2010 4:46 PM
>
>>From: Gary Thomas [mailto:gary at mlbassoc.com]
>>Sent: Thursday, December 16, 2010 12:10 AM
>>
>>Note to Richard: I'm still seeing a ton of Noexec messages every time I rebuild
>>a package in this tree.  I thought I understood you to say they should happen
>>at most once?
>>
>
>Yes, RP's previous patch does reduce the Noexec messages a lot. However there
>remains one problem. Current stamp file check also calculates the stamp of tasks
>depended on. If those stamps are newer or not exist, the check return False to
>indicate mismatched stamp.
>
>In 'noexec' case, some 'noexec' tasks happen to have some dependent tasks
>skipped which thus don't generate stamp files. This makes the check always
>failed for those 'noexec' tasks and thus you always observe the Noexec messages.
>
>I have a patch to fix that, and will send out soon. :-)
>

Though I managed to remove the rest 'noexec' messages by adding below in 
check_stamp_task():

	if 'noexec' in taskdep and taskname in taskdep['noexec']
		return True

I realized there's one potential risk. Though 'noexec' task is not executed at all,
it's considered to be a normal task which normally plays the role of the sync
points. Ideally if there're changes on stamp file of tasks that this 'noexec' task
depends on, we still want to generate a new stamp file for the 'noexec' task.
That way other tasks depending on that 'noexec' task will trigger rebuild too.

If we always take 'noexec' task away from the comparison, above chain effect
disappears.

Current comparison condition for stamp files is:

	if not t2 or t1 < t2
		iscurrent = False

I'm not sure under which case a stamp file (t2) doesn't exist, and whether it's
safe to use:
	if not t2 and not noexec or t2 and t1 < t2:
		iscurrent = False

to check stamp file for 'noexec' task.

Or alternative is to simply convert bb.note to bb.debug for 'noexec' message. :-)

Thanks
Kevin