[yocto] Using PACKAGECONFIG

[Paul Eggleton]

On Thursday 09 April 2015 15:16:58 Paul Eggleton wrote:
> Hi Gary,
> 
> On Thursday 09 April 2015 07:45:47 Gary Thomas wrote:
> > I'm trying to extend PACKAGECONFIG for a recipe (vlc).  The
> > 
> > main recipe contains this:
> >    PACKAGECONFIG ?= " live555"
> >    PACKAGECONFIG[mad] = "--enable-mad,--disable-mad,libmad"
> >    PACKAGECONFIG[a52] = "--enable-a52,--disable-a52,liba52"
> >    PACKAGECONFIG[jack] = "--enable-jack,--disable-jack,jack"
> >    PACKAGECONFIG[live555] = "--enable-live555,--disable-live555,live555"
> >    PACKAGECONFIG[libass] = "--enable-libass,--disable-libass,libass"
> >    PACKAGECONFIG[mkv] = "--enable-mkv,--disable-mkv,libmatroska libebml"
> >    PACKAGECONFIG[postproc] =
> > 
> > "--enable-postproc,--disable-postproc,libpostproc" PACKAGECONFIG[opencv] =
> > "--enable-opencv,--disable-opencv,opencv" PACKAGECONFIG[libva] =
> > "--enable-libva --enable-avcodec,--disable-libva --disable-avcodec,libva
> > libav"
> > 
> > I'd like to only add "libva" to the default, so I wrote this
> > 
> > in my local.conf:
> >    PACKAGECONFIG_pn-vlc_append = " libva"
> > 
> > Inspecting it
> > 
> >    $ bitbake vlc -e | grep ^PACKAGECONFIG
> >    PACKAGECONFIG=" libva"
> > 
> > Oops.  Just to be sure, I tried
> > 
> >    PACKAGECONFIG_pn-vlc = "live555 libva"
> > 
> > which gives
> > 
> >    $ bitbake vlc -e | grep ^PACKAGECONFIG
> >    PACKAGECONFIG="live555 libva"
> > 
> > Note: I tried
> > 
> >    PACKAGECONFIG_append_pn-vlc = " libva"
> > 
> > which does work.  However, I've also used
> > 
> >    PACKAGECONFIG_pn-chromium_append = " component-build"
> > 
> > for a different recipe that does work... VERY CONFUSED
> > 
> > What am I doing wrong?  How do I correctly add to the default list?
> 
> In general, for a conditional append, you must use _append_<override> - the
> other way around will not do an append, AFAIK it will just set the value.
> 
> There are some other valid options that you didn't mention above:
> 
> 1) Set it outright to list all of the options you want instead of appending.
> At least you know exactly what is going into the value. (I know some people
> don't like this.)
> 
> 2) Set it using += or _append from a bbappend.

(although I hasten to add, += from a bbappend will only work if the original 
value is set with ?= rather than ??=... probably safest to stick with _append)

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre