[oe] Prebuilt toolchains

[Chris Conroy]

On Fri, 2009-11-13 at 07:06 -0700, Gary Thomas wrote:
> On 11/11/2009 02:29 PM, Chris Conroy wrote:
> > On Wed, 2009-11-11 at 14:07 -0700, Gary Thomas wrote:
> >>
> >> Thanks for the pointer.  Given that I'm really new with OE, can you
> >> give me a clue as to how to use that recipe?  Can I just add some
> >> magic to my local.conf to make this work (instead of the lines quoted above)?
> >>
> >
> > Sure thing. Sadly the snapshot of OE that we're working with internally
> > had some issues which required us to pull a few changes from poky and
> > make some local changes which I haven't been able to push upstream yet.
> > Long story short, I'm not 100% in sync with trunk here so you may need
> > to change a couple of things, but this will get you most of the way
> > there. Most of my issues were in the creation, not in the sourcing of
> > the toolchain.
> >
> > We allow developers to choose between an "external" or "scratch" (let OE
> > build it) toolchain and use a paradigm similar to the pokymode. In my
> > local.conf I have
> >
> >> TOOLCHAIN="external"
> >
> > In my distro conf I have:
> >
> >> #Default to build the toolchain if no external one is selected
> >> TOOLCHAIN ?= "scratch"
> >> require conf/toolchain-${TOOLCHAIN}.conf
> >
> > My toolchain-external.conf looks like:
> >> PREFERRED_PROVIDER_linux-libc-headers = "external-toolchain"
> >> PREFERRED_PROVIDER_glibc-thread-db = "external-toolchain"
> >> PREFERRED_PROVIDER_libstdc++-dev = "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}gcc = "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}g++ = "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}gcc-initial = "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}gcc-intermediate =  "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}binutils = "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/binutils = "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/${TARGET_PREFIX}libc-for-gcc =  "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/libc =  "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/libintl =  "external-toolchain"
> >> PREFERRED_PROVIDER_virtual/libiconv =  "external-toolchain"
> >>
> >>
> >> TOOLCHAIN_OPTIONS = " --sysroot=${STAGING_DIR_HOST}"
> >> PATH =. "${SDK_PREFIX}/bin:"
> >
> > I believe the SDK_PREFIX is a pokyism. I also pulled in the BUILDSDK_CPPFLAGS and friends from poky.
> >
> > in bitbake.conf...
> >> export BUILDSDK_CPPFLAGS = "-isystem${STAGING_INCDIR}"
> >> export BUILDSDK_CFLAGS = "${BUILDSDK_CPPFLAGS} ${BUILD_OPTIMIZATION}"
> >> export BUILDSDK_LDFLAGS = "-L${STAGING_LIBDIR} \
> >>                      -Wl,-rpath-link,${STAGING_LIBDIR} \
> >>                      -Wl,-rpath,${libdir} -Wl,-O1"
> >
> > in sdk.bbclass...
> >> CPPFLAGS = "${BUILDSDK_CPPFLAGS}"
> >> CFLAGS = "${BUILDSDK_CFLAGS}"
> >> CXXFLAGS = "${BUILDSDK_CFLAGS}"
> >> LDFLAGS = "${BUILDSDK_LDFLAGS}"
> >
> >
> > Hopefully that helps. Ideally this stuff would just work out of the box, but it sounds like the toolchain setup is going to get a major makeover soon.
> 
> I've tried this setup and it _almost_ works.  I still have
> a problem though in that it insists on building gcc-cross
> (which is failing for some reason).
> 
> I can't figure out why gcc-cross is required, nor how to
> override/remove this dependency.
> 
> Any ideas?

I'd say definitely take a look at the dependency graph of whatever is
trying to build gcc-cross (bitbake -g <package>) and inspect the
depends.dot and task-depends.dot. Inspect the output of 

bitbake -n -DDD <package> | less -i

Look for gcc-cross in the output and see why it's being chosen. Looking
at my local setup, it seems that I have 

> DEBUG: sorted providers for virtual/mipsel-linux-gcc are: 
> ['/home/cconroy/p4/new_trunk/hcrest.build/packages/meta/external-toolchain.bb', 
> '/home/cconroy/p4/new_trunk/hcrest.build/packages/gcc/gcc-cross_4.2.3.bb']

If you find you have something similar, but just in the wrong order, you
may need to pull my recently accepted bitbake patch which fixes how it
works with priorities.



Also, I found it helpful to turn the "multiple providers" state in
bitbake into a fatal error condition. I can't recall if I ran into this
problem or not, but it's possible this will help:

In your lib/bb/runqueue.py you'll see a commented fatal error:
#if error:
#	bb.msg.fatal(bb.msg.domain.RunQueue, "Corrupted metadata configuration
detected, aborting...")

If you activate that error you may find this to be the cause of your
problem. If so, you may want to make the message a bit more verbose and
dump out the offending package and providers.

Hope that helps!

--Chris