Re: [PATCH] sstate.bbclass: preserve time when unstaging files

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Mon, 2012-10-29 at 17:24 +0100, Enrico Scholz wrote:
> Richard Purdie <richard.purdie@linuxfoundation.org> writes:
> 
> >> When packages are recreated after a 'bitbake -c clean', files will get
> >> wrong date because tar has been invoked with the '-m' option.
> >> 
> >> Correct timestamps are useful for bug hunting and there are better
> >> ways (e.g. using of ntp) than using '-m'.
> >
> > This is a revert of:
> >
> > http://git.yoctoproject.org/cgit.cgi/poky/commit/?id=2d89cff42af2bb0049224bfaaebaa2b21966169f
> >
> > where the option was added deliberately to deal with time mismatch
> > between autobuilders which was causing real world bugs.
> 
> But the real bug is the time mismatch in the autobuilders, isn't it?
> And this can/should be solved by synchronizing time by ntp on them
> instead of applying dirty hacks like resetting file dates.

I have asked that ntp be installed/fixed on the autobuilders to sort the
problem out but it seems that even with ntp running, mismatches can
happen (e.g. misconfigured timezones). Worse, when this does happen the
failures are extremely unpredictable and hard to debug. It causes things
to repeatedly recompile for example, even during do_install.

So no, I don't think this is a dirty hack, its part of ensuring the
builds are deterministic and helping people avoid what can be a very
nasty and hard to debug set of build issues.

I appreciate it hurts some other debugging forensics but I'd rather that
than anyone suffering some of the nasty build failures I debugged.

Cheers,

Richard