1021 ### Creating And Using Sysroots With qemu-deboostrap

  1022 

  1023 Fortunately, you can create sysroots for foreign architectures with tools

  1024 provided by your OS. On Debian/Ubuntu systems, one could use `qemu-deboostrap` to

  1025 create the *target* system chroot, which would have the native libraries and headers

  1026 specific to that *target* system. After that, we can use the cross-compiler on the *build*

  1027 system, pointing into chroot to get the build dependencies right. This allows building

  1028 for foreign architectures with native compilation speed.

  1029 

  1030 For example, cross-compiling to AArch64 from x86_64 could be done like this:

  1031 

  1032   * Install cross-compiler on the *build* system:

  1033 ```

  1034 apt install g++-aarch64-linux-gnu gcc-aarch64-linux-gnu

  1035 ```

  1036 

  1037   * Create chroot on the *build* system, configuring it for *target* system:

  1038 ```

  1039 sudo qemu-debootstrap --arch=arm64 --verbose \

  1040        --include=fakeroot,build-essential,libx11-dev,libxext-dev,libxrender-dev,libxtst-dev,libxt-dev,libcups2-dev,libfontconfig1-dev,libasound2-dev,libfreetype6-dev,libpng12-dev \

  1041        --resolve-deps jessie /chroots/arm64 http://httpredir.debian.org/debian/

  1042 ```

  1043 

  1044   * Configure and build with newly created chroot as sysroot/toolchain-path:

  1045 ```

  1046 CC=aarch64-linux-gnu-gcc CXX=aarch64-linux-gnu-g++ sh ./configure --openjdk-target=aarch64-linux-gnu --with-sysroot=/chroots/arm64/ --with-toolchain-path=/chroots/arm64/

  1047 make images

  1048 ls build/linux-aarch64-normal-server-release/

  1049 ```

  1050 

  1051 The build does not create new files in that chroot, so it can be reused for multiple builds

  1052 without additional cleanup.

  1053 

  1054 Architectures that are known to successfully cross-compile like this are:

  1055 

  1056   Target        `CC`                      `CXX`                       `--arch=...` `--openjdk-target=...`

  1057   ------------  ------------------------- --------------------------- ------------ ----------------------

  1058   x86           default                   default                     i386         i386-linux-gnu

  1059   armhf         gcc-arm-linux-gnueabihf   g++-arm-linux-gnueabihf     armhf        arm-linux-gnueabihf

  1060   aarch64       gcc-aarch64-linux-gnu     g++-aarch64-linux-gnu       arm64        aarch64-linux-gnu

  1061   ppc64el       gcc-powerpc64le-linux-gnu g++-powerpc64le-linux-gnu   ppc64el      powerpc64le-linux-gnu

  1062   s390x         gcc-s390x-linux-gnu       g++-s390x-linux-gnu         s390x        s390x-linux-gnu

  1063 

  1064 Additional architectures might be supported by Debian/Ubuntu Ports.

  1065