On Tue, Apr 07, 2015 at 08:52:36AM -0600, Gary Thomas wrote:
> I'm building for multiple ARM i.MX6 platforms.  These have
> the same SoC, but slightly different peripherals. As far as
> I can tell, they should be able to share everything except
> for a few ${MACHINE} specific packages, e.g. the kernel and
> u-boot.
> 
> Sadly, that doesn't seem to be the case.  The architecture
> specific packages are being split into two categories - plain
> ARM/Cortex-A9 and those that have i.MX6 specific optimizations.
> For example, after building a complete image (on the order of
> core-image-sato), I have this split:
> $ ls tmp/work/cortexa9hf-vfp-neon-amltd-linux-gnueabi/
> acl                  gst-player                 libsamplerate0         modutils-initscripts  shadow-sysroot
> alsa-utils           gst-plugins-bad            libsm                  mpeg2dec              shared-mime-info
> apmd                 gst-plugins-good           libsndfile1            mplayer2              speex
> atk                  gst-plugins-ugly           libsoup-2.4            mtdev                 sqlite3
> attr                 gstreamer                  libtheora              ncurses               startup-notification
> base-passwd          gstreamer1.0               libtirpc               neon                  strace
>     ...
> gst-ffmpeg           libpostproc                matchbox-wm            scrnsaverproto        zlib
> gst-fluendo-mpegmux  libproxy                   mkfontdir              settings-daemon
> gst-meta-base        libpthread-stubs           mkfontscale            shadow
> 
> $ ls tmp/work/cortexa9hf-vfp-neon-mx6qdl-amltd-linux-gnueabi/
> alsa-lib      gst-plugins-base           imx-gpu-viv  libfslparser   libsdl      xf86-video-imxfb-vivante
> cairo         gstreamer1.0-plugins-bad   libdrm       libfslvpuwrap  mesa        xserver-xorg
> firmware-imx  gstreamer1.0-plugins-base  libfslcodec  libglu         pulseaudio
> 
> It's the second category that is causing problems.  They do not
> seem to end up in any shareable sstate at all.  If I try to rebuild
> using only sstate, i.e. build my complete image to success, then
> remove 'tmp' and rebuild, using the sstate-cache from the first go,
> all of the above packages (alsa-lib, ..., xserver-xorg) are all
> rebuilt from scratch.  Those recipes do seem to end in my sstate-cache,
> but they are never reused from it.
> 
> What would make this happen?  How can I prevent it?
> 
> As is, sstate is not really shareable between these i.MX6 targets
> as so much is being rebuilt all the time...
> 
> Any ideas or pointers gladly welcomed.

Try openembedded-core/scripts/sstate-diff-machines.sh
to see why.

-- 
Martin 'JaMa' Jansa     jabber: Martin.Jansa@gmail.com