[Buildroot] luajit package fails to build on x86_64 for x86

[Yann E. MORIN <yann.morin.1998@free.fr>]

Fabio, All,

On 2014-03-06 11:43 +0100, Fabio Porcedda spake thusly:
> Hi all,
> luajit fails to build on a Ubuntu 13.10 x86_64 with the following defconfig:
> 
> BR2_x86_generic=y
> BR2_TOOLCHAIN_EXTERNAL=y
> BR2_PACKAGE_LUAJIT=y
> 
> 
> with the following build error:
> 
> CC        luajit.o
> HOSTLINK  host/minilua
> /usr/bin/ld: skipping incompatible
> /usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc.a when searching for -lgcc
> /usr/bin/ld: cannot find -lgcc
> /usr/bin/ld: skipping incompatible
> /usr/lib/gcc/x86_64-linux-gnu/4.8/libgcc_s.so when searching for
> -lgcc_s
> /usr/bin/ld: cannot find -lgcc_s
> collect2: error: ld returned 1 exit status
> make[3]: *** [host/minilua] Error 1
> make[2]: *** [amalg] Error 2
> make[1]: *** [amalg] Error 2
> make: *** [/e/buildroot/br-tmp/output/build/luajit-2.0.2/.stamp_built] Error 2

Yes, that's somewhat expected.

From luajit.mk:

    # The luajit build procedure requires the host compiler to have the
    # same bitness as the target compiler. Therefore, on a x86 build
    # machine, we can't build luajit for x86_64, which is checked in
    # Config.in. When the target is a 32 bits target, we pass -m32 to
    # ensure that even on 64 bits build machines, a compiler of the same
    # bitness is used. Of course, this assumes that the 32 bits multilib
    # libraries are installed.

I tries here, and I have a bigger problem (line continuations manually
added for readability):

    HOSTCC    host/minilua.o
    /usr/bin/gcc -m32  -O2 -fomit-frame-pointer -Wall   -I. \
        -DLUAJIT_TARGET=LUAJIT_ARCH_x86 -DLJ_ARCH_HASFPU=1  \
        -DLJ_ABI_SOFT FP=0 -O2                              \
        -I/home/ymorin/dev/buildroot/O/host/usr/include -c  \
        -o host/minilua.o host/minilua.c
    In file included from <command-line>:0:0:
    /usr/include/stdc-predef.h:30:26: fatal error: bits/predefs.h: No such
    file or directory
     #include <bits/predefs.h>
                              ^
    compilation terminated.
    make[4]: *** [host/minilua.o] Error 1
    make[3]: *** [amalg] Error 2
    make[2]: *** [amalg] Error 2
    make[1]: *** [/home/ymorin/dev/buildroot/O/build/luajit-2.0.2/.stamp_built] Error 2
    make: *** [_all] Error 2
    Command exited with non-zero status 2

And this can not work on a pure 64-bit system (aka, without the 32-bit
legacy stuff).

Note: my kernel does have 32-bit legacy support, but my system does not
have the development (-dev stuff with headers and .so symlinks) userland
installed, only the runtime. So I can actually _run_ 32-bit stuff, just
not _generate_ any...

Not sure how we can get away with this...

Regards,
Yann E. MORIN.

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