Hi.
I'm trying to cross compile C-python 2.7.10 for an embedded system. (Eg:
a Kobo reader).
But there appears to be some bugs that do not allow the latest
maintenance release of Python to correctly cross compile on an x86-64
build system, for a 32 bit arm system.
I have researched the problem, and there are apparently two different bugs;
1'st -- the Makefile doesn't disable PYTHONPATH for the arm libraries,
and the x86 64 bit platform will attempt to link to the arm libraries
during the compile process producing an wrong elf class error.
I found some online examples of cross compiling older versions of python
which suggest adding a '-' before "PYTHONPATH' to prevent that from
happening. When I do that, it does compile -- but:
2'nd -- If I build python 2.7.10 with the above change, and with no
debugging information or switches; it builds fine, but the resulting
binary segfaults randomly on the Kobo reader, and will not import
libraries without segfaulting.
If I build it with all available debugging information (-g3 -ggdb
-gdwarf 4), the random segfaulting stops -- and instead, python raises
an exception any time I attempt to import a library.
-----------------------------------------------------------------------
Python 2.7.10 (default, Jun 29 2015, 23:00:31)
[GCC 4.8.1 20130401 (prerelease)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import math
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: /mnt/user/lib/python2.7/lib-dynload/math.so: undefined
symbol: Py_InitModule4
[40857 refs]
>>>
-------------------------------------------------------------------------
The symbol is indeed missing when I check with nm, and from what little
information I can find online -- this appears to have something to do
with a 32 bit vs. 64 bit incompatibility; eg: even though it's compiling
for 32 bits ARM -- it still seems to be trying to use symbols associated
with 64 bit processing.
I attempted to compile a 32 bit python interpreter on the build system,
to make PYTHON_FOR_BUILD, and PGEN_FOR_BUILD ; but it didn't rectify the
problem.
What is the proper way to cross compile 2.7.10 for 32 bit arm, on a
x86_64 bit platform / what am I doing wrong ?
--------------------------------------------------------------------------------------
Supplimentary information:
I'm using the linaro-gcc compiler from the kobolabs git repository, ()
eg: an arm-linux-gnueabihf-gcc on a 64 bit Slackware 14.1 machine with
multilib x86 gcc available on the build system.
I have a separate 8GB partition with the Kobo kernel source code,
stdlibs, etc. all installed from the github source and compiled to a
target directory stored in an environment variable called ${DEVICEROOT}
; All files found on the KOBO reader are located under ${DEVICEROOT} on
the BUILD machine, and the arm GCC processor uses -I
${DEVICEROOT}/usr/include and other appropriate paths so that GCC finds
them naturally.
The following bash script shows the steps I used to compile Python with
-- and it is followed by another bash script which sets up the compile
environment variables, so you can see how the compiler environment is
configured.
I have no problem compiling C source code in general using the Kobo
compiler tools, and have compiled gnuplot, and bash, and several other
packages with absolutely no problems. It is only python which is not
compiling correctly.
----------------------------------------------------------------------------------------------------------------------------------------------
set -x
# A parser generator and build system version of python are supposed to be
# needed to run parts of the cross compilation; I do see python used in
the
# Makefile, but no references to a buid version of PGEN are defined,
# so I don't know if PGEN gets used or not -- but I build it anyway...
# As this is what receipies on the web say to do...
make distclean
(
. /etc/profile.d/32dev.sh
export LIBDIRSUFFIX=""
./configure # --build=x86_64-unknown-linux-gnu
--host=i486-unknown-linux-gnu #(uncomment to build 32bit)
make Parser/pgen python
mv python python_for_build
mv Parser/pgen Parser/pgen_for_build
make distclean
)
# fix setup.py to handle installing to the target system's fake install
# directory found on the build system at $DEVICEROOT.
# We want utf-8, unicode terminal handling -- so make sure python compiles
# with ncursesw substituted for curses.
CURSESFLAGS=`pkg-config --cflags ncursesw`
# Configure python to be built
CFLAGS="${CFLAGS} ${CURSESFLAGS} -g3 -ggdb -gdwarf-4" ./configure
--host=${CROSSTARGET} --build=i486-unknown-linux-gnu --enable-unicode
--enable-shared --with-pydebug --prefix=/mnt/user --disable-ipv6
--without-pymalloc ac_cv_file__dev_ptmx=yes ac_cv_file__dev_ptc=no
ac_cv_have_long_long_format=yes PYTHON_FOR_BUILD=${PWD}/python_for_build
PGEN_FOR_BUILD=${PWD}/Parser/pgen_for_build
# Fix a bug in the Makefile
# The build version of python, ought not try to actually use the ARM
libraries.
sed -i -e 's%\([[:space:]]\)\(PYTHONPATH=$(DESTDIR)$(LIBDEST)\)%\1-\2%'
Makefile
echo "background the process now to Fix the makefile manually if you can"
sleep 10
make PYTHON_FOR_BUILD=${PWD}/python_for_build CROSS_COMPILE_TARGET=yes
echo " Waiting to allow you to see error messages before installing "
sleep 10
# Optionally, binary file stripping could be carried out on the python
binary
# Don't strip if you are doing debugging of python
# strip --strip-unneeded python
make install DESTDIR=${DEVICEROOT}
PYTHON_FOR_BUILD=${PWD}/python_for_build
PGEN_FOR_BUILD=${PWD}/Parser/pgen_for_build
----------------------------------------------------------------------------------------------------------------
###### A bash file used to set up gcc paths for cross compiling on the
kobo follows a (-----).
# There are two compilers in the KOBO git repository:
# https://github.com/kobolabs/Kobo-Reader/tree/master/toolchain
# a linaro-gcc, and code-sourcery-gcc. The code sourcery gcc does not
have the standard C libraries and
# perhaps does not use hardware floats, or have those startup files, and
is strictly for compiling the linux kernel.
# Only the linaro compiler is needed to compile Python.
# The linaro compiler is invoked by using ${CROSSTARGET} as a prefix,
while the kernel compiler is invoked
# using ${CROSS_COMPILE}
# eg: use arm-linux-gnueabihf-gcc for linaro vs.
arm-none-linux-gnueabi-gcc for code sourcercy (kernel compiler).
#
# All tools are installed on a partition or thumb drive, with the
following bash script located at THUMBDRIVEPATH/.local/bin and the path
added to my user PATH.
# The script will auto locate the gcc tools relative to its' own install
directory, so THUMBDRIVE path can be changed without needing to
re-editing the script.
# I installed the linaro compiler, path relative, at:
#
THUMBDRIVEPATH/.local/gcc-linaro-arm-linux-gnueabihg-4.8-2013.04-20130417_linux/
... etc.
----------------------------------------------------------------------------------------------------------------
#!/bin/bash --init-file
# this file is: use_kobo
echo "Starting subshell with KOBO/ARM linaro gcc and Sourcery_G++_Lite
in the path"
set -e
path=`whereis -b use_kobo`
name="${path%%:*}"
path="${path##* /}"
path="/${path%%/${name}}"
export SOURCERYDIR=${path}/../CodeSourcery/Sourcery_G++_Lite
export
LINARODIR=${path}/../gcc-linaro-arm-linux-gnueabihf-4.8-2013.04-20130417_linux
echo "Adding CodeSourcery eabi and linaro eabihf compiler suites to the
path"
export PATH=${SOURCERYDIR}/bin:${LINARODIR}/bin:${PATH}
export KOBOLABS=${path}/../../KoboLabs
export DEVICEROOT=${KOBOLABS}/deviceroot
#export CROSSTARGET="arm-none-linux-gnueabi"
export CROSSTARGET="arm-linux-gnueabihf"
# Build the linux kernel with these variables
export CROSS_COMPILE="arm-none-linux-gnueabi-"
export ARCH="arm"
# Clean out system shell varaibles that can affect program compilation
unset CC
unset CFLAGS
unset LDFLAGS
unset CPPFLAGS
unset CPP
unset CXX
unset CXXFLAGS
unset CXXCPP
unset C_INCLUDE_PATH
unset CPLUS_INCLUDE_PATH
unset QT4DIR
unset OBJC_INCLUDE_PATH
unset PKG_CONFIG_PATH
unset PKG_CONFIG_LIBDIR
unset PKG_CONFIG_SYSROOT_DIR
mkdir -p /tmp/kobo-gcc-cross
export TMPDIR=/tmp/kobo-gcc-cross
export CPATH=${DEVICEROOT}/usr/include:${DEVICEROOT}/mnt/user/include
export
LIBRARY_PATH="${DEVICEROOT}/lib:${DEVICEROOT}/usr/lib":${DEVICEROOT}/mnt/user/lib
export LDFLAGS="-L${DEVICEROOT}/lib -L${DEVICEROOT}/usr/lib
-L${DEVICEROOT}/mnt/user/lib"
# Set up PKGCONFIG to prefer programs that were compiled later, over
earlier.
export
PKG_CONFIG_PATH="${DEVICEROOT}/mnt/user/lib/pkgconfig:${DEVICEROOT}/usr/lib/pkgconfig:${DEVICEROOT}/lib/pkgconfig"
export PKG_CONFIG_LIBDIR="${PKG_CONFIG_PATH}"
export PKG_CONFIG_SYSROOT_DIR="${DEVICEROOT}"
cleanup() {
echo -e '\033]2;Unknown xterm\007'
trap EXIT
exit $1 $2 $3 $4
}
trap cleanup EXIT
echo -e '\033]2;ARM Sourcery_G++_Lite & linaro-gcc for KOBO shell\007'
set +e
set -o vi
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