Develop Reference

How to build boost 1.69.0 for Android with NDK r18b using dec1/Boost-for-Android?

I tried to use https://github.com/dec1/Boost-for-Android to compile boost for Android. It reports 1.69.0 is supported for NDK r18b. I'm under Windows 7.
Even if this is reported as working, I encounter many problems when trying to run the provided script:
Downloaded boost 1.69.0
Downloaded sources
Modified BOOST_SRC_DIR to point to folder containing "1.69.0" boost folder
Modified ANDROID_NDK_ROOT to point to ndk folder
Modified ABIS="armeabi-v7a,x86"
Modified LINKAGE="static"
Added Cygwin to my path (as this is a .sh file I need to run)
Ran doIt.sh
Got non blocking errors:
-nLe fichier sp?cifi? est introuvable.
ERROR: Unsupported HOST_TAG: windows-x86_64
Then I got final error
## COMMAND: mkdir /tmp/ndk-/tmp/build-11600/build-boost/armeabi-v7a/llvm/host-bin
## COMMAND: ./bootstrap.sh --with-toolset=cc Building Boost.Build engine
with toolset cc... Failed to build Boost.Build build engine Consult
'bootstrap.log' for more details ERROR: Could not bootstrap Boost build
'bootstrap.log'reports gcc: not found
Added MinGW to my PATH (to have gcc be found), then retried:
Now I get in 'bootstrap.log':
cc -o bootstrap/jam0 command.c compile.c constants.c debug.c execcmd.c frames.c function.c glob.c hash.c hdrmacro.c headers.c jam.c jambase.c jamgram.c lists.c make.c make1.c object.c option.c output.c parse.c pathsys.c regexp.c rules.c scan.c search.c subst.c timestamp.c variable.c modules.c strings.c filesys.c builtins.c class.c cwd.c native.c md5.c w32_getreg.c modules/set.c modules/path.c modules/regex.c modules/property-set.c modules/sequence.c modules/order.c execunix.c fileunix.c pathunix.c
command.c:1:0: sorry, unimplemented: 64-bit mode not compiled in
There is no 'cc' available in my PATH, dunno where this is supposed to be found
Any idea what I may be doing wrong?

Sorry, only building on linux is officially supported. Mac and Windows should work fine too but details of setting up the relevant environments (eg cgwin or homebrew) is beyond the scope of what this project tries to do.
If you want to use windows as a host you have two easiest options are:
Use virtual machines eg. VirtualBox or and create a linux virtual machine where you do the building.
You can also simply download and use the precompiled binaries I have made available
No matter what os you use to build under, the resulting binaries can then be copied to windows and used from then on as if you had built on windows to start with (theyre cross compiled for android).

How to compile boost 1.68.0 for Android using NDK r18b using Windows

I had to build a version of boost for Android using NDK r18b, I had a hardtime achieving this so I post Question+Answer here as it may help other persons.
Firstly, I tried https://github.com/moritz-wundke/Boost-for-Android, but this was unsuccessful, see How to build boost 1.69.0 for Android with NDK r18b using moritz-wundke/Boost-for-Android?.
Secondly, I tried https://github.com/dec1/Boost-for-Android, but this was unsuccessful too, see How to build boost 1.69.0 for Android with NDK r18b using dec1/Boost-for-Android?.
What are the steps to follow to achieve compilation of boost?

Actually, those scripts were designed for Linux, and they hardly work under Windows. Then, I started from scratch and could finally find the good config under Windows to achieve this. I basically checked how other libraries are compiled (I use QtCreator to deploy on Android, so the compilation window reported me how clang++ has to be invoked, so I write a user-config.jam based on that.
Here are the steps to follow to compile boost 1.68.0 for Android armeabiv7 and x86 using NDK r18b:
Download boost 1.68.0 from boost.org: https://www.boost.org/users/history/version_1_68_0.html
Apply moritz-wundke's patch, else it won't compile (thanks by the way). Take it from here: https://github.com/moritz-wundke/Boost-for-Android/tree/master/patches
Run bootstrap.bat (you'll need it to find a compiler, I have VS 2015 installed so it works just fine)
Then set some environment variables:
set ANDROIDNDKROOT=C:\Android\android-ndk-r18b (change this accordingly)
set NDKVER=r18b
set CLANGPATH=%ANDROIDNDKROOT%\toolchains\llvm\prebuilt\windows-x86_64\bin
Copy user-config.jam to boost folder tools/build/src:
import os ;
local AndroidNDKRoot = [ os.environ ANDROIDNDKROOT ] ;
local AndroidBinariesPath = [ os.environ CLANGPATH ] ;
using clang : armeabiv7a
:
$(AndroidBinariesPath)/clang++
:
<compileflags>-fexceptions
<compileflags>-frtti
<compileflags>-mthumb
<compileflags>-ffunction-sections
<compileflags>-funwind-tables
<compileflags>-fstack-protector-strong
<compileflags>-Wno-invalid-command-line-argument
<compileflags>-Wno-unused-command-line-argument
<compileflags>-no-canonical-prefixes
<compileflags>-I$(AndroidNDKRoot)/sources/cxx-stl/llvm-libc++/include
<compileflags>-I$(AndroidNDKRoot)/sources/cxx-stl/llvm-libc++abi/include
<compileflags>-I$(AndroidNDKRoot)/sources/android/support/include
<compileflags>-DANDROID
<compileflags>-Wa,--noexecstack
<compileflags>-Wformat
<compileflags>-Werror=format-security
<compileflags>-DNDEBUG
<compileflags>-D_REENTRANT
<compileflags>-O2
<compileflags>-gcc-toolchain
<compileflags>$(AndroidNDKRoot)/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64
<compileflags>-target
<compileflags>armv7-linux-androideabi
<compileflags>-march=armv7-a
<compileflags>-mfloat-abi=softfp
<compileflags>-mfpu=vfp
<compileflags>-fno-builtin-memmove
<compileflags>-fpic
<compileflags>-DHAVE_CONFIG_H
<compileflags>-fno-integrated-as
<compileflags>--sysroot
<compileflags>$(AndroidNDKRoot)/sysroot
<compileflags>-isystem
<compileflags>$(AndroidNDKRoot)/sysroot/usr/include/arm-linux-androideabi
<compileflags>-D__ANDROID_API__=18
<archiver>$(AndroidNDKRoot)/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/arm-linux-androideabi/bin/ar
<ranlib>$(AndroidNDKRoot)/toolchains/arm-linux-androideabi-4.9/prebuilt/windows-x86_64/arm-linux-androideabi/bin/ranlib
;
# --------------------------------------------------------------------
using clang : x86
:
$(AndroidBinariesPath)/clang++
:
<compileflags>-fexceptions
<compileflags>-frtti
<compileflags>-mthumb
<compileflags>-ffunction-sections
<compileflags>-funwind-tables
<compileflags>-fstack-protector-strong
<compileflags>-Wno-invalid-command-line-argument
<compileflags>-Wno-unused-command-line-argument
<compileflags>-no-canonical-prefixes
<compileflags>-I$(AndroidNDKRoot)/sources/cxx-stl/llvm-libc++/include
<compileflags>-I$(AndroidNDKRoot)/sources/cxx-stl/llvm-libc++abi/include
<compileflags>-I$(AndroidNDKRoot)/sources/android/support/include
<compileflags>-DANDROID
<compileflags>-Wa,--noexecstack
<compileflags>-Wformat
<compileflags>-Werror=format-security
<compileflags>-DNDEBUG
<compileflags>-D_REENTRANT
<compileflags>-O2
<compileflags>-gcc-toolchain
<compileflags>$(AndroidNDKRoot)/toolchains/x86-4.9/prebuilt/windows-x86_64
<compileflags>-target
<compileflags>i686-linux-android
<compileflags>-march=i686
<compileflags>-mfloat-abi=softfp
<compileflags>-mfpu=vfp
<compileflags>-fno-builtin-memmove
<compileflags>-fPIC
<compileflags>-mstackrealign
<compileflags>--sysroot
<compileflags>$(AndroidNDKRoot)/sysroot
<compileflags>-isystem
<compileflags>$(AndroidNDKRoot)/sysroot/usr/include/i686-linux-android
<compileflags>-D__ANDROID_API__=18
<archiver>$(AndroidNDKRoot)/toolchains/x86-4.9/prebuilt/windows-x86_64/i686-linux-android/bin/ar
<ranlib>$(AndroidNDKRoot)/toolchains/x86-4.9/prebuilt/windows-x86_64/i686-linux-android/bin/ranlib
;
Then, for armeabiv7-a:
Run bjam -q --without-math --without-context --without-coroutine --without-fiber --without-python architecture=arm --ignore-site-config -j4 target-os=android toolset=clang-armeabiv7a link=static threading=multi --layout=tagged --build-dir=build/arm/%NDKVER% --stagedir=stage_arm_%NDKVER% stage
Then, for x86:
Run bjam -q --without-math --without-context --without-coroutine --without-fiber --without-python architecture=arm --ignore-site-config -j4 target-os=android toolset=clang-armeabiv7a link=static threading=multi --layout=tagged --build-dir=build/arm/%NDKVER% --stagedir=stage_arm_%NDKVER% stage
Hopefully, the same steps can be followed to compile 1.69.0 (not tested)

Thanks for the helpful instructions.
moritz-wundke/Boost-for-Android is a great project and the original Boost-for-Android. However, the way it works, it requires constant maintenance in order to support each new combination of the ndk and boost as new versions come out (you can only build for the explicit versions the project has been configured to support). After a long time (boost version 1.53 -> 1.63, and ndk 10->16) where its seemed like the project was no longer being maintained, and my efforts to contact the maintainer were in vain, I decided to fork it, which is why dec1/Boost-for-Android came into existence.
It has the advantage that it does not, in general, need to be updated to support new versions of google's ndk, or boost. They generally build out of the box, or need rare adjustments (but I still test regularly to make sure).
Using dec1/Boost-for-Android is arguably also simpler (certainly than following your instructions above). You can build for any/all architectures (arm64-v8a, armeabi-v7a, x86, x86_64), in one go in a single line of code. And if you dont need a custom build you can simply download prebuilt binaries (boost 1.69.0, with ndk 19 and 18b, both dynamic and static are now also available) from here. There's also an example app to help you test your build.
Im pretty sure that it could be made to work on windows or mac too (possibly with less effort than you spent above), but its a lot easier to just use a virtual machine (eg the free virtualbox) to do the build, and copy the resulting binaries to windows if you really want to develop there.
Nonetheles, moritz-wundke/Boost-for-Android seems to have gotten a new influx of contributions of late, which is good news for everybody. And if you find it more suitable for building boost on windows (or any other platform) then thats great.
Good luck with your projects and thanks again for the insights.

Crosscompile Perl for Android x86

I like to crosscompile Perl for the Android x86 emulator. But I got a PIE (position independent executables) error on running Configure... Based on this and this tutorial.
Specs:
NDK version 14
Perl 5.22.1.
x86 Android emulator built with AOSP - Android 7.1.1
I set following variables:
export ANDROID_NDK=/home/fabian/Android/Sdk/ndk-bundle
export TARGET_ARCH=x86
export ANDROID_TOOLCHAIN=/tmp/toolchain-x86
export SYSROOT=$ANDROID_TOOLCHAIN/sysroot
export TARGETDIR=/data/local/perl
export GCC=i686-linux-android-gcc
export PATH=$PATH:$ANDROID_NDK/toolchains/x86-4.9/prebuilt/linux-x86_64/bin
Then I build the toolchain with following command:
$ANDROID_NDK/build/tools/make-standalone-toolchain.sh --platform=android-23 --install-dir=$ANDROID_TOOLCHAIN --toolchain=x86-4.9
and get this (correct?) output:
HOST_OS=linux
HOST_EXE=
HOST_ARCH=x86_64
HOST_TAG=linux-x86_64
HOST_NUM_CPUS=4
BUILD_NUM_CPUS=8
Auto-config: --arch=x86
Toolchain installed to /tmp/toolchain-x86.
Then I start the ./Configure command:
./Configure -des -Dusedevel -Dusecrosscompile -Dtargetrun=adb -Dcc=i686-linux-android-gcc -Dsysroot=$SYSROOT -Dtargetdir=$TARGETDIR -Dtargethost=emulator-5554
and got this output:
First let's make sure your kit is complete. Checking...
Would you like to see the instructions? [n]
Locating common programs...
Checking compatibility between /bin/echo and builtin echo (if any)...
Symbolic links are supported.
Checking how to test for symbolic links...
You can test for symbolic links with 'test -h'.
Using targetarch i686-linux-android.
Using targethost emulator-5554.
Building host miniperl and generate_uudmap binaries
Using targethost emulator-5554.
Guessing targetuser root.
Guessing targetport 22.
Using '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/run-adb' for remote execution,
and '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/from-scp' and '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/to-scp'
for remote file transfer.
Good, your tr supports [:lower:] and [:upper:] to convert case.
Using [:upper:] and [:lower:] to convert case.
aix_3 dragonfly irix_4 nonstopux stellar
aix_4 dynixptx irix_5 openbsd sunos_4_0
aix dynix irix_6_0 opus sunos_4_1
altos486 epix irix_6_1 os2 super-ux
amigaos esix4 irix_6 os390 svr4
atheos fps isc_2 os400 svr5
aux_3 freebsd isc posix-bc ti1500
bitrig freemint linux-android powerux ultrix_4
bsdos genix linux qnx umips
catamount gnukfreebsd lynxos riscos unicosmk
convexos gnuknetbsd midnightbsd sco_2_3_0 unicos
cxux gnu mips sco_2_3_1 unisysdynix
cygwin greenhills mirbsd sco_2_3_2 utekv
darwin haiku mpc sco_2_3_3 uwin
dcosx hpux ncr_tower sco_2_3_4 vos
dec_osf i386 netbsd sco
dos_djgpp interix newsos4 solaris_2
Which of these apply, if any? [linux-android]
"./a.out": error: only position independent executables (PIE) are supported.
Aborted
You don't have an ELF gcc. I will use dld if possible. If you are
using a version of DLD earlier than 3.2.6, or don't have it at all, you
should probably upgrade. If you are forced to use 3.2.4, you should
uncomment a couple of lines in hints/linux.sh and restart Configure so
that shared libraries will be disallowed.
Disabling ndbm. This will generate a Whoa There message in Configure.
Read hints/linux.sh for further information.
Operating system name? [linux-android]
Operating system version? [7.1.1]
Installation prefix to use? (~name ok) [/usr/local]
AFS does not seem to be running...
What installation prefix should I use for installing files? (~name ok)
[/usr/local]
Getting the current patchlevel...
Build a threading Perl? [n]
Build Perl for multiplicity? [n]
Use which C compiler? [i686-linux-android-gcc]
Checking for GNU cc in disguise and/or its version number...
"./try": error: only position independent executables (PIE) are supported.
Aborted
Now, how can we feed standard input to your C preprocessor...
Directories to use for library searches?
[/tmp/toolchain-x86/sysroot/usr/lib/../lib /tmp/toolchain-x86/sysroot/usr/lib]
What is the file extension used for shared libraries? [sa]
Make shared library basenames unique? [n]
Hmm. Based on the hints in hints/linux-android.sh,
the recommended value for $d_libname_unique on this machine was "define"!
Keep the recommended value? [y]
Build Perl for SOCKS? [n]
Try to use long doubles if available? [n]
Checking for optional libraries...
What libraries to use? [-lm -lc]
What optimizer/debugger flag should be used? [-O2]
Any additional cc flags?
[-DOVR_DBL_DIG=14 --sysroot=/tmp/toolchain-x86/sysroot]
Let me guess what the preprocessor flags are...
Any additional ld flags (NOT including libraries)?
[ --sysroot=/tmp/toolchain-x86/sysroot]
Checking your choice of C compiler and flags for coherency...
I've tried to compile and run the following simple program:
#include
int main() { printf("Ok\n"); return(0); }
I used the command:
i686-linux-android-gcc -o try -O2 -DOVR_DBL_DIG=14 --sysroot=/tmp/toolchain-x86/sysroot --sysroot=/tmp/toolchain-x86/sysroot try.c -lm -lc
/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/run-adb-shell ./try
and I got the following output:
The program compiled OK, but exited with status 134.
You have a problem. Shall I abort Configure [y]
Ok. Stopping Configure.
OK I have to set the flags
Modify config.sh to enable PIE support. Append “-fPIE” to ccflags and
“-fPIE -pie” to ldflags. Then rerun configure to ensure this is
applied.
But there is no config.sh in the perl folder, so I tried this ./Configure command:
`./Configure -des -Dusedevel -Dusecrosscompile -Dtargetrun=adb -Dcc=i686-linux-android-gcc -Dsysroot=$SYSROOT -Dtargetdir=$TARGETDIR -Dtargethost=emulator-5554 -Dccflags='-fPIE' Dldflags='-fPIE -pie'`
but same problem again...
First let's make sure your kit is complete. Checking...
Would you like to see the instructions? [n]
Locating common programs...
Checking compatibility between /bin/echo and builtin echo (if any)...
Symbolic links are supported.
Checking how to test for symbolic links...
You can test for symbolic links with 'test -h'.
Using targetarch i686-linux-android.
Using targethost emulator-5554.
Building host miniperl and generate_uudmap binaries
Using targethost emulator-5554.
Guessing targetuser root.
Guessing targetport 22.
Using '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/run-adb' for remote execution,
and '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/from-scp' and '/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/to-scp'
for remote file transfer.
Good, your tr supports [:lower:] and [:upper:] to convert case.
Using [:upper:] and [:lower:] to convert case.
aix_3 dragonfly irix_4 nonstopux stellar
aix_4 dynixptx irix_5 openbsd sunos_4_0
aix dynix irix_6_0 opus sunos_4_1
altos486 epix irix_6_1 os2 super-ux
amigaos esix4 irix_6 os390 svr4
atheos fps isc_2 os400 svr5
aux_3 freebsd isc posix-bc ti1500
bitrig freemint linux-android powerux ultrix_4
bsdos genix linux qnx umips
catamount gnukfreebsd lynxos riscos unicosmk
convexos gnuknetbsd midnightbsd sco_2_3_0 unicos
cxux gnu mips sco_2_3_1 unisysdynix
cygwin greenhills mirbsd sco_2_3_2 utekv
darwin haiku mpc sco_2_3_3 uwin
dcosx hpux ncr_tower sco_2_3_4 vos
dec_osf i386 netbsd sco
dos_djgpp interix newsos4 solaris_2
Which of these apply, if any? [linux-android]
"./a.out": error: only position independent executables (PIE) are supported.
Aborted
You don't have an ELF gcc. I will use dld if possible. If you are
using a version of DLD earlier than 3.2.6, or don't have it at all, you
should probably upgrade. If you are forced to use 3.2.4, you should
uncomment a couple of lines in hints/linux.sh and restart Configure so
that shared libraries will be disallowed.
Disabling ndbm. This will generate a Whoa There message in Configure.
Read hints/linux.sh for further information.
Operating system name? [linux-android]
Operating system version? [7.1.1]
Installation prefix to use? (~name ok) [/usr/local]
AFS does not seem to be running...
What installation prefix should I use for installing files? (~name ok)
[/usr/local]
Getting the current patchlevel...
Build a threading Perl? [n]
Build Perl for multiplicity? [n]
Use which C compiler? [i686-linux-android-gcc]
Checking for GNU cc in disguise and/or its version number...
"./try": error: only position independent executables (PIE) are supported.
Aborted
Now, how can we feed standard input to your C preprocessor...
Directories to use for library searches?
[/tmp/toolchain-x86/sysroot/usr/lib/../lib /tmp/toolchain-x86/sysroot/usr/lib]
What is the file extension used for shared libraries? [sa]
Make shared library basenames unique? [n]
Hmm. Based on the hints in hints/linux-android.sh,
the recommended value for $d_libname_unique on this machine was "define"!
Keep the recommended value? [y]
Build Perl for SOCKS? [n]
Try to use long doubles if available? [n]
Checking for optional libraries...
What libraries to use? [-lm -lc]
What optimizer/debugger flag should be used? [-O2]
Any additional cc flags?
[-DOVR_DBL_DIG=14 -fPIE --sysroot=/tmp/toolchain-x86/sysroot]
Let me guess what the preprocessor flags are...
Any additional ld flags (NOT including libraries)?
[ --sysroot=/tmp/toolchain-x86/sysroot]
Checking your choice of C compiler and flags for coherency...
I've tried to compile and run the following simple program:
#include
int main() { printf("Ok\n"); return(0); }
I used the command:
i686-linux-android-gcc -o try -O2 -DOVR_DBL_DIG=14 -fPIE --sysroot=/tmp/toolchain-x86/sysroot --sysroot=/tmp/toolchain-x86/sysroot try.c -lm -lc
/home/fabian/Desktop/Testimages/perl-5.22.1/Cross/run-adb-shell ./try
and I got the following output:
"./try": error: only position independent executables (PIE) are supported.
Aborted
The program compiled OK, but exited with status 134.
You have a problem. Shall I abort Configure [y]
Ok. Stopping Configure.
But now the ccflag is set how you can see in the last lines...
Did I miss something?

Compile and use boost for Android NDK R10e

How do I compile and use Boost for the Android NDK? I've tried everything I've found online, from Boost for Android to compiling it myself with the bjam file. However, I do not succeed. When I try compiling it with bjam, I get the following error:
error: toolset gcc initialization:
error: version 'androidR10e' requested but 'g++-androidR10e' not found and version '4.2.1' of default 'g++' does not match
error: initialized from /path/to/android-ndk-r10e/sources/boost/tools/build/v2/user-config.jam:86
Has anyone successfully used Boost with Android NDK R10e?
And when I can compile it, how should I do to use it in my Android app project?

We managed to compile it for NDKr10d. It should be the same for NDKr10e.
The project-config.bjam should point to the gcc compiler from the NDK. Ours looks like this :
import option ;
using gcc : arm : D:\\android\\ndk\\toolchains\\arm-linux-androideabi-4.9\\prebuilt\\windows-x86_64\\bin\\arm-linux-androideabi-g++.exe ;
option.set keep-going : false ;
Then just compile with b2, telling paths to android includes :
b2 --reconfigure <your options>
toolset=gcc-arm
include=<ndk folder>\sources\cxx-stl\gnu-libstdc++\4.9\include
include=<ndk folder>\sources\cxx-stl\gnu-libstdc++\4.9\libs\<target platform>\include
include=<ndk folder>\platforms\<android api version>\arch-arm\usr\include
install --libdir=stage\lib\<target platform>
We're about to move to ndkr10e. Could you tell if boost still works with it ? :)

The simplest way would be to use CrystaX NDK, which contains already built and ready-to-use Boost libraries. And here are examples how to use Boost with CrystaX NDK: 1, 2

Following the boost directions, I was able to build boost 1.60 with NDKr10e on Ubuntu 12.04 (although I suspect very little depends on the host system). Here are my notes:
get and unpack boost source tarball (i used 1.60): boost_1_60_0.tar.bz2
moskewcz#maaya:/scratch/moskewcz/android/src$ ll
total 74M
drwx------ 10 moskewcz moskewcz 4.0K Mar 9 14:14 boost_1_60_0
-rw-rw-r-- 1 moskewcz moskewcz 74M Jan 5 11:15 boost_1_60_0.tar.bz2
follow boost instructions in getting started on unix "Build Custom Binaries" section
use a fresh, empty root to install b2 i.e. /scratch/boost-build-root; use usr as prefix; again following the boost instructions:
moskewcz#maaya:/scratch/moskewcz/android/src/boost_1_60_0/tools/build$ ./bootstrap.sh
moskewcz#maaya:/scratch/moskewcz/android/src/boost_1_60_0/tools/build$ ./b2 install --prefix=/scratch/moskewcz/android/boost-build-root/usr
put b2 in path (again as per instructions)
export PATH=/scratch/moskewcz/android/boost-build-root/usr/bin:$PATH
in some jamfile (i had no ~/user-config.jam, so i created one and used that, maybe there's a better choice of jamfile to create/edit) add some jam-code (?) to define a gcc version (toolset) pointing to a g++ from a standalone toolchain. note that this is a toolchain created with the NDK in the normal fashion following its 'create a standalone toolchain' directions. i am NOT pointing to a g++ inside the NDK itself (that may or may not work, i dunno):
import option ;
using gcc : arm_linux_android_4.9 : /scratch/android-stc/bin/aarch64-linux-android-g++ ;
option.set keep-going : false ;
go to boost project root and build, mostly as per directions. --build-dir may be optional? also added -j8 to do || build
moskewcz#maaya:/scratch/moskewcz/android/src/boost_1_60_0$ b2 -j8 --build-dir=bin.v2 toolset=gcc-arm_linux_android_4.9 stage
note that this tries to build both static and shared libs by default, but building shared libs fails due to android not having librt.so -- according to my research, people claim that under android (some of?) the functionality of librt.so is inside libc.so -- so it may be okay to simply remove -lrt from the linking steps in order to build shared libs for android. i did not attempt this. see:
https://code.google.com/p/android/issues/detail?id=5730
Building Boost for Android with error "cannot find -lrt"

I only managed to build with 10d. Cross compiling Linux->Android using Boost for Android worked straight away with that.
To download a slightly outdated ndk, as not all ndk are immediately supported by Boost for Android, you can use this guide: Where do I find old versions of Android NDK?
Note: I also wanted to specify the toolchain. I had to do it in 2 places:
In build-android.sh, just after the line mentioned here above:
TOOLCHAIN=${TOOLCHAIN:-arm-linux-androideabi-4.9}
In the command line
bash build-android.sh [ndk location] --toolchain=arm-linux-androideabi-4.9
In fact, it worked better when I specified exactly which boost components I wanted with --with-libraries=[comma separated list].
If instead I would build everything, I would get:
...failed updating 38 targets...
...skipped 6 targets...
...updated 10568 targets...
ERROR: Failed to build boost for android!
Done!

Here: http://silverglint.com/boost-for-android/ you can find a simple and painless new way to build a modern (eg 1.64.0) version of boost for android.
Works with clang and gcc.
Also included is a sample app that shows you how to use the boost binaries thus built.

How to build i686-linux-android-gfortran for android-ndk8b (x86 arch Android)?

I tried building i686-linux-android-gfortran using build-gcc.sh following this
(it's for androdindk-7b) but I get error about link.h. I added link.h from here, but it gives further more errors.
Has anyone tried enabling i686-linux-android-gfortran for x86 Android?

From https://groups.google.com/forum/#!msg/android-ndk/QR1qiN0jIpE/g0MHkhTd4YMJ as selalerer suggested. I didn't try this, so I'm posting as a community wiki for reference purposes.
Fortran for x86 Android
=================
The guide is based on this one, many thanks to Phil:
Compiling Android NDK with Objective-C-enabled gcc errors
1) Download and unpack Android NDK 'android-ndk-r8c', (the older -r8b NDK won't work due to missing link.h!):
wget http://dl.google.com/android/ndk/android-ndk-r8c-linux-x86.tar.bz2
2) Create somewhere a folder called 'toolchain-src' (e.g. inside the folder android-ndk-r8c),
'cd' to this new folder
3) Make sure to have git installed ('yum install git' or whatever..) and download
the toolchain sources:
git clone https://android.googlesource.com/toolchain/build.git
git clone https://android.googlesource.com/toolchain/gmp.git
git clone https://android.googlesource.com/toolchain/gdb.git
git clone https://android.googlesource.com/toolchain/mpc.git
git clone https://android.googlesource.com/toolchain/mpfr.git
git clone https://android.googlesource.com/toolchain/expat.git
4) Create the folder 'binutils', 'cd' to this directory, unpack
binutils-2.23 there:
wget ftp.gnu.org/gnu/binutils/binutils-2.23.tar.gz
tar -xvzf binutils-2.23.tar.gz
You should now have a folder toolchain-src/binutils/binutils-2.23
5) Change to folder toolchain-src/build, edit the Makefile.in, changing the line:
--with-gnu-as --with-gnu-ld --enable-languages=c,c++
to
--with-gnu-as --with-gnu-ld --enable-languages=c,c++,fortran
6) In the file android-ndk-r8c/build/tools/build-mingw64-toolchain.sh change the line:
var_append GCC_CONFIGURE_OPTIONS "--enable-languages=c,c++"
to
var_append GCC_CONFIGURE_OPTIONS "--enable-languages=c,c++,fortran"
7) In the file android-ndk-r8c/build/tools/build-gcc.sh, change the line:
EXTRA_CONFIG_FLAGS=$EXTRA_CONFIG_FLAGS" --disable-libquadmath --disable-plugin"
to
EXTRA_CONFIG_FLAGS=$EXTRA_CONFIG_FLAGS" --disable-libquadmath --disable-libquadmath-support --disable-plugin"
8) In the file android-ndk-r8c/build/tools/build-host-gcc.sh, change the line:
ARGS=$ARGS" --enable-languages=c,c++"
to
ARGS=$ARGS" --enable-languages=c,c++,fortran"
And change the line
ARGS=$ARGS" --disable-libquadmath --disable-plugin --disable-libitm --disable-bootstrap"
to
ARGS=$ARGS" --disable-libquadmath --disable-libquadmath-support --disable-plugin --disable-libitm --disable-bootstrap"
9) Build your new toolchain:
/your/path/to/android-ndk-r8c/build/tools/build-gcc.sh -j1 --gmp-version=5.0.5 --mpfr-version=2.4.2 --mpc-version=0.8.1 --binutils-version=2.23 --gdb-version=7.3.x /your/path/to/toolchain-src /your/path/to/android-ndk-r8c x86-4.7
(don't worry about messages like 'expr: warning: unportable BRE:')
10) And go down to your knees in front of the screen, praying to the Lord that somehow these
countless configure scripts doing checks that nobody needs, using an ugly shell language
that cooks your brain with indentation going from right to left, will somehow manage to
compile a zillion of far too small files (so that 10% of the time is spent on compilation
and 90% on starting up GCC), and after an hour of watching progress with
tail -F /tmp/ndk-YourUserName/build/toolchain/config.log
your toolchain will be magically ready. You'll find it in the android-ndk-r8c/toolchains folder.
11) Finally, 'cd' to the folder
'/your/path/to/android-ndk-r8c/toolchains/x86-4.7/prebuilt/linux-x86/i686-linux-android'
and run this command:
ln -s ../libexec libexec
Without this command, it may happen that g++ raises the error message
"g++: fatal error: -fuse-linker-plugin, but liblto_plugin.so not found".
Using strace, I found that g++ looks in the wrong folder, but the link
above lets it find the file liblto_plugin.so nevertheless.
And here are a few lessons learned on the way, so that Google finds this page:
*) To speed up the compilation, you can remove the '-j1'. But only after you got
it to work once, since building in parallel on multiple CPU cores was reported to
cause additional troubles.
*) The error message "Link tests are not allowed after GCC_NO_EXECUTABLES" shows up
when linking fails for x86 (works for ARM). The reason is that GCC does not include
the proper ANDROID_STARTFILE_SPEC and ANDROID_ENDFILE_SPEC from
gcc-4.6.1/gcc/config/linux-android.h. GCC 4.6.1 only specifies them for ARM, but not
for i386, GCC 4.8.0 however does. The GCCs downloaded from Google also do,
so best use Google's GCC.
*) The error message "fatal error: link.h: No such file or directory" also happens
with Google's GCC, and apparently (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50877)
only when you enable additional languages like objc or fortran.
The bug thread is here: http://gcc.gnu.org/ml/gcc-bugs/2012-08/msg00494.html
MIPS has link.h in android-ndk-r8b/platforms/android-9/arch-mips/usr/include
In android-ndk-r8c, link.h is now also present in android-9/arch-x86/usr/include/link.h,
so this bug was fixed.
*) The error message "fatal error: quadmath_weak.h: No such file or directory":
It also happens with the latest gcc-4.8, so we can just continue using Googles GCC 4.7.
Google itself uses --disable-libquadmath, but we additionally need --disable-libquadmathsupport
(see http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47648). So this needs to be added in
android-ndk-r8c/build/tools/build-gcc.sh
and
android-ndk-r8c/build/tools/build-host-gcc.sh
*) The error message "error: Pthreads are required to build libatomic"
Happens when building the ARM version of gcc-4.8 downloaded from gnu.org,
better stay with Google's GCCs.
*) The GCC that came with android-ndk-r8c didn't work for me (error message about
libstdc++.so.6 being too old), while the one in android-ndk-r8b worked
without problems. Since the android-ndk should support as many environments
as possible, I'm not sure why the Googlers decided to depend on a newer libstdc++,
but the good news are that building your own toolchain solves the issue.
*) If you get an error while compiling generic-morestack.c, then replace
#ifdef linux
// On Linux, the first two real time signals are used by the NPTL
with
#if defined(GLIBC) && defined(linux)
// On Linux, the first two real time signals are used by the NPTL