Re: go-cross: incorrect dependency on tune-specific libgcc

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Tue, 2017-04-11 at 09:39 -0700, Khem Raj wrote:
> On Tue, Apr 11, 2017 at 9:34 AM, Patrick Ohly <patrick.ohly@intel.com
> > wrote:
> > 
> > On Mon, 2017-04-10 at 14:49 +0200, Patrick Ohly wrote:
> > > 
> > > Hello!
> > > 
> > > I'm currently extending the yocto-compat-layer.py so that it can
> > > detect
> > > invalid signature changes when changing MACHINE. go-cross-x86_64
> > > shows
> > > up as broken when comparing signatures for MACHINE=intel-corei7-
> > > 64 and
> > > MACHINE=qemux86-64.
> > > 
> > > Both machines share the same go-cross-x86_64, but that DEPENDS on
> > > libgcc:
> > > 
> > > meta/recipes-devtools/go/go.inc:# libgcc is required for the
> > > target specific libraries to build properly
> > > meta/recipes-devtools/go/go.inc:DEPENDS += "go-bootstrap-native
> > > libgcc"
> > > 
> > > And libgcc itself depends on the tune flags for the target
> > > architecture
> > > and thus is different for these two machines:
> > > 
> > > $ bitbake-diffsigs -t go-cross-x86_64 do_prepare_recipe_sysroot
> > > -s 563f419e3854c2351e2cbbf33a9025f6
> > > 64e378fd9853a6cd6a4e7f684f52d2fc
> > > Hash for dependent task gcc/libgcc_6.3.bb.do_populate_sysroot
> > > changed from afb6b55c0e2b7d2e816b3d2d214a7326 to
> > > 208fac5ae428b07a4aa491b130879e4a
> > >   Hash for dependent task gcc/libgcc_6.3.bb.do_multilib_install
> > > changed from 596e1612d7b84b7a9c1b409ee78cca89 to
> > > d41e2e835d0abe7646e53e3d63ce00cd
> > >     Hash for dependent task gcc/libgcc_6.3.bb.do_install changed
> > > from 9ca4126c69fcceb410253a0603c3d76b to
> > > cb0c49687a91ea17f1027c6394baacab
> > >       Hash for dependent task gcc/libgcc_6.3.bb.do_compile
> > > changed from ab80902424c73af49257cc3f6fe049aa to
> > > 436f978a703476968bd5ae1c1915ee5a
> > >         Hash for dependent task gcc/libgcc_6.3.bb.do_configure
> > > changed from eb0c36d87f32ce1ceb7d1e42609578fb to
> > > f62c98806faf3a28c2144919b89d3460
> > >           Hash for dependent task
> > > gcc/libgcc_6.3.bb.do_prepare_recipe_sysroot changed from
> > > b037b950e346bef71a4f8fd2c6a2195c to
> > > d4564b5730941279392932e3c670a5a5
> > >             Hash for dependent task gcc/libgcc_6.3.bb.do_fetch
> > > changed from e64cd9e029ed63ba3a09e5fe085b7057 to
> > > ea4d3f9d10544219ceb8591d5a5a4041
> > >               basehash changed from
> > > 8744593af2eddb60244788f2b9476e2d to
> > > dabeb22478ef501e35311af75119a2cf
> > >               Variable TUNE_CCARGS value changed:
> > >               " -m64 [--march=corei7 -mtune=corei7-] {+-
> > > march=core2 -mtune=core2 -msse3+} -mfpmath=sse [--msse4.2-]"
> > > 
> > > Does this fix look correct? It turns go-cross into a package that
> > > is
> > > specific to the tune flags for the target.
> > [...]
> > 
> > > 
> > > The alternative would be to drop the libgcc dependency, but I
> > > have no
> > > idea whether that would work at all.
> > Besides Bruce who pointed out the implications on recipes depending
> > on
> > go-cross-${TARGET_ARCH}, Richard also had concerns about making go-
> > cross
> > tune-specific, so I ended up testing the libgcc removal approach.
> > It
> > happened to build okay, so the patch that I ended up proposing (see
> > "go-cross: avoid libgcc dependency") just removes libgcc from
> > DEPENDS
> > for go-cross.
> > 
> > I need to revise the method how its done (i.e. not with
> > DEPENDS_remove),
> > but besides that, can anyone explain whether such a change might
> > hit
> > some problems somewhere? Khem?
> > 
> I think TUNE_PKGARCH is the granularity it needs for setting GOARM
> anyway. It should be fine to change it.

Once we go down the TUNE_PKGARCH route we probably won't get back. I'm
reluctant to give up on this quite so easily since having common tools
make a lot of sense from a build time perspective (and we already have
fun with testing and the time it takes).

We could make arm append a v7 to PN in the v7 case and only have two go
compilers on arm to address the GOARM issue...

Cheers,

Richard