Re: Current state of multilib support (powerpc)

[Alexey Neyman <stilor at att dot net>]

Hi,

On 05/18/2016 02:11 PM, Bryan Hundven wrote:
> (Added Alexey Neyman, who did the multilib work)
> > On May 18, 2016, at 5:33 AM, Thomas De Schampheleire <patrickdepinguin@gmail.com> wrote:
> >
> > Hi Bryan,
> >
> > On Tue, May 17, 2016 at 3:50 PM, Bryan Hundven <bryanhundven@gmail.com> wrote:
> > > > On May 17, 2016, at 6:19 AM, Thomas De Schampheleire <patrickdepinguin@gmail.com> wrote:
> > > >
> > > > Hi,
> > > >
> > > > In 2014 there has been some work on multilib support in crosstool-ng,
> > > > by Bryan Hundven, Cody P. Schafer, and Ray Donnelly. See e.g. mail
> > > > threads [1] and [2].
> > > >
> > > > It looks as if this work has not been integrated in crosstool-ng.
> > > > Meanwhile also the bitbucket branch referenced in the threads no
> > > > longer exists and I can't find the corresponding branches on github.
> > > >
> > > > What is the latest state of this work?
> > > > Where are the latest patches?
> > > > What are the remaining problems?
> > > >
> > > > I'm currently interested in a multilib toolchain 32/64 bit for
> > > > Freescale e6500 processors.
> > > > I ported one of Cody's patches to crosstool-ng 1.22.0 and the build
> > > > advanced a bit further than with the 1.22.0 baseline, but now breaks
> > > > at the 'pass-2 core C gcc compiler' step.
> > > >
> > > > Thanks,
> > > > Thomas
> > > >
> > > > [1] https://sourceware.org/ml/crossgcc/2014-01/msg00054.html
> > > > [2] https://sourceware.org/ml/crossgcc/2014-07/msg00014.html
> > > See here: https://github.com/crosstool-ng/crosstool-ng/pull/383
> > >
> > > Please test and review.
> Alexey, could you help out with this one?
>
> > Interesting, thanks!
> >
> > I created a toolchain based on that PR with the following configuration:
> >
> > CT_PREFIX_DIR="${CT_TOP_DIR}/targets/${CT_TARGET}"
> > CT_ARCH_CPU="e6500"
> > CT_ARCH_64=y
> > CT_ARCH_powerpc=y
> > CT_MULTILIB=y
> > CT_KERNEL_linux=y
> > CT_KERNEL_V_3_18=y
> > CT_BINUTILS_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"
> > CT_CC_GCC_V_4_9_3=y
> > CT_CC_GCC_CORE_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"
> > CT_CC_GCC_EXTRA_CONFIG_ARRAY="--enable-targets=powerpc-linux,powerpc64-linux"
> > CT_CC_GCC_MULTILIB_LIST="powerpc-linux,powerpc64-linux"
> > CT_CC_LANG_CXX=y
> >
> > The idea is that 32-bit should be the default, without requiring
> > additional options on the compiler command-line.
> >
> > When passing this toolchain to buildroot, applications seems to build
> > fine in 32-bit (I did not try to run them yet).
> > The kernel is also correctly built in 64-bit.
> > However, there is something wrong for u-boot. I get errors like:
> >
> > /foo/output/host/usr/bin/powerpc64-unknown-linux-gnu-ld.bfd:
> > Relocatable linking with relocations from format elf32-powerpc
> > (arch/powerpc/cpu/mpc8xxx/cpu.o) to format elf64-powerpc
> > (arch/powerpc/cpu/mpc8xxx/built-in.o) is not supported
> >
> > which indicates that the default format used by ld.bfd is 64-bit
> > rather than 32-bit. If I manually replay this command-line with the
> > additional -m elf32ppc, it seems to work correctly and a 32-bit
> > builtin.o is created.
> >
> > What am I missing? Why is ld not taking 32-bit as default, while gcc is?
> >
> > (I did not post to the github PR because it may all be caused by a
> > misconfiguration or misunderstanding on my part).
> >
> > Thanks,
> > Thomas


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