[boost] Problem cross-compiling boost.context for Raspberry Pi (2)

Subject: [boost] Problem cross-compiling boost.context for Raspberry Pi (2)
From: Biddiscombe, John A. (biddisco_at_[hidden])
Date: 2015-06-16 02:22:22

Hello list,

I am able to compile the full set of boost libraries on the Raspberry Pi, and I get all the libraries successfully built, including context and coroutine which I need. However, when I cross compile on an Ubuntu virtual machine setup for the job, all the libraries except context/coroutine are built.

The problem seems to be that when cross compiling, the file "unsupported.cpp" is being pulled in (here is a verbose output showing flag I'm using)

    "/home/biddisco/pi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf-g++"  -ftemplate-depth-128 -O3 -finline-functions -Wno-inline -Wall -pthread -fPIC -D__arm__  -std=c++11 -mcpu=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard -DBOOST_ALL_NO_LIB=1 -DBOOST_CHRONO_DYN_LINK=1 -DBOOST_CONTEXT_DYN_LINK=1 -DBOOST_CONTEXT_SOURCE -DBOOST_SYSTEM_DYN_LINK=1 -DBOOST_SYSTEM_NO_DEPRECATED -DBOOST_THREAD_BUILD_DLL=1 -DBOOST_THREAD_POSIX -DBOOST_THREAD_USE_DLL=1 -DNDEBUG  -I"." -c -o "bin.v2/libs/context/build/gcc-arm/release/threading-multi/unsupported.o" "libs/context/src/unsupported.cpp"

which emanates from the jamfile boost_1_58_0/libs/context/build/Jamfile.v2 where the following
alias asm_context_sources
   : unsupported.cpp
   ;
is in a section marked #COMBINED

Now, when I build on the pi itself, this file is not being added to the build, so it seems to me that during the bootstrap phase on the pi, different flags are being used which trigger the correct behaviour of bjam

my user-config.jam looks like this

using gcc : : /home/biddisco/pi/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian-x64/bin/arm-linux-gnueabihf-g++ : <compile-flags>-D__arm__ -mcpu=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard ;

(NB. I added -D__arm__ to see if it helps, but it does not make a difference without it).

I have no knowledge of how bjam / boost.build do their things, so I do not know what to try next. It seems that I need to bootstrap the build using the flags for the pi, but built for the host so that it can generate the correct makefiles and this looks like where the problem is arising.
the build process seems good apart from this wrinkle

The bootstrap command I'm using is
./bootstrap.sh --with-toolset=gcc

and the build appears sensible when I use
./b2  cxxflags="-D__arm__  -std=c++11 -mcpu=cortex-a7 -mfpu=neon-vfpv4 -mfloat-abi=hard"  --layout=versioned threading=multi link=shared variant=release -j8

Performing configuration checks
    - 32-bit                   : yes
    - arm                      : yes

.... etc etc

Can anyone see what I'm doing wrong?

(Note : With another project which depends on libpthread, I had to copy libpthread from the pi to the host and force the linker to use the pthread lib from the pi and not the host one, does bjam do something internally which might require a trick like this? - note2 - the binaries generated via this process run without error)

Many thanks

JB

--
John Biddiscombe,                        email:biddisco @.at.@ cscs.ch
http://www.cscs.ch/
CSCS, Swiss National Supercomputing Centre  | Tel:  [phone]
Via Trevano 131, 6900 Lugano, Switzerland   | Fax:  [phone]