Re: Current state of multilib support (powerpc)

[Bryan Hundven <bryanhundven at gmail dot com>]

(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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