[poky] ccache

[Richard Purdie]

On Tue, 2012-04-10 at 20:51 -0400, Bob Cochran wrote:
> On 04/03/2012 01:36 PM, Chris Larson wrote:
> > On Tue, Apr 3, 2012 at 10:31 AM, Gary Thomas<gary at mlbassoc.com>  wrote:
> >> Why is ccache being used for Poky/Yocto builds?  My understanding is
> >> that it's a win for _rebuilds_ of the same/related files, but there's
> >> not a whole lot of that going on.
> >>
> >> If I build core-image-sato from scratch, I end up with ${BUILD}/tmp/ccache
> >> which is 1.8GB - quite a bite!  Is there some way to disable this?, other
> >> than not have ccache on my host computer (not an option as it is useful
> >> for other builds I do)
> >
> > I think the default behavior of using ccache when it's installed is
> > extremely bad, and dangerous, in that the ccache object cache is of
> > both limited usefulness, as you say, and the object cache can get
> > corrupted, leading to extremely odd behavior (and it's rarely a place
> > you think to look as a cause). At Mentor we disabled this behavior,
> > and I really, really think we should do so in the default oe-core
> > bitbake.conf.
> 
> 
> It would be nice / cleaner to not build out the hollow ccache directory 
> structure under tmp when ccache isn't installed or being used.  Seeing 
> it there under tmp with levels of empty sub directories beneath it is 
> somewhat confusing.

I'm tempted to move all the ccache stuff into a separate class and then
drop the inherit by default.

Patches welcome for 1.3...

Cheers,

Richard