Re: Recompiles in Yocto/Poky

[Markus Lehtonen <markus.lehtonen@linux.intel.com>]

Hi,

There would be at least two options,that I can think of to "hide" the
files. First, if possible, make the recipe build in a separate
directory so that the build-time generated files won't pollute your
source tree. Second, make your external source tree a Git tree and add
the files in question to .gitignore. 

Thanks,
  Markus

On Wed, 2016-06-08 at 04:50 +0000, Keskinarkaus, Teemu wrote:
> Hi,
> 
> I think there are some files that are being generated at compilation
> time so most likely those triggers the recompilation every time.
> 
> The next question is that how to I 'hide' files so that they don't
> trigger the recompilation? Is that something that I need to do on my
> application side or can I list files in Yocto to ignore when hashing
> files? This is most likely the proper way to deal with this issue
> rather than disabling whole feature.
> 
> Teemu Keskinarkaus
> Software system engineer
> maximatecc
> making machines smart, safe and productive
> 
> 
> -----Original Message-----
> From: Paul Eggleton [mailto:paul.eggleton@linux.intel.com]
> Sent: 8. kesäkuuta 2016 4:52
> To: Peter Kjellerstedt; Keskinarkaus, Teemu
> Cc: poky@yoctoproject.org
> Subject: Re: [poky] Recompiles in Yocto/Poky
> 
> On Fri, 03 Jun 2016 07:00:14 Peter Kjellerstedt wrote:
> > This is a feature introduced to complement the main use of
> > externalsrc, which is together with devtool. When you use "devtool
> > modify -x <recipe>", it fetches the sources as specified in the
> > recipe
> > and makes them available locally. At the same time it sets up a
> > bbappend in the workspace layer which uses externalsrc to use those
> > sources when building the recipe. This is intended to make it easy
> > to
> > use BitBake to actually work on and develop the sources. However,
> > for
> > this to work in practice, BitBake must rebuild the package if there
> > are any changes in the sources, but since BitBake normally only
> > looks
> > at the meta data to determine if a recipe task needs to run, there
> > is
> > nothing telling it that the sources have changed. Therefore changes
> > were made so that code specified using externalsrc is always
> > rebuilt.
> 
> In 2.0 that's how it behaved - what it's supposed to do in 2.1 is
> determine if the sources have changed by either relying on the git
> metadata (if the source tree is tracked in git) or by hashing all
> files in the source tree if it isn't. It could be false triggering if
> you have files in the source tree that get regenerated as part of the
> compilation process that aren't hidden. Teemu, is that the case for
> your source tree?
> 
> Unfortunately there is no way at present to turn off this
> functionality; we could add one, however before doing that I would be
> more interested in looking at making the code more intelligent so it
> did automatically rebuild in response to source changes for this case
> and not when there were no changes, assuming that's practical.
> 
> Cheers,
> Paul
> 
> --
> 
> Paul Eggleton
> Intel Open Source Technology Centre
> 
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