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• Launchpad Entry: https://blueprints.launchpad.net/ubuntu-arm/+spec/arm-m-cross-compilers/

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• Packages affected:

Summary

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Unresolved issues

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BoF agenda and discussion

Discussions from UDS-M

Improve packaging of cross-compilers

Overall goal: try to script creation of cross-compiler packages and allow in archive cross-compilers (and not out of archive + manually built)

• Improve support for -sysroot
• Merge the binary-cross target into binary for e.g. gcc
• Other simplifications of gcc/binutils etc. packaging to allow replacing these
• Provide .dsc + .diff.gz etc. in the -source packages.

First goal:

• have x-compiler packages of the same version and targeting the same toolchain as the native compilers
• compiler targeting arm running on x86 obvious first goal
• also can target e.g. uclibc

Existing approach: dpkg-cross, other highly manual approaches.

Can't run it in build environment because you can't build-depend on arm versions of packages.

Boot Strapping

Bootstrap from source:

• linux
• binutils
• gcc
• eglibc
• gcc
• eglibc
• gcc

Emdebian bootstrap:

• dpkg-cross <long list>

• binutils
• gcc binary-cross
• eglibc binary-cross

Bootstrap of cross-compiler requires building glibc-initial, then gcc-cross-initial, glibc, gcc-cross.

Could build e.g. glibc-arm package that could be installable on x86, but it would be ugly to provide an arm package as arch: all

Check how gcc-mingw32 is done?

• support is split into few packages:
  • mingw32-runtime (headers + libraries)
  • mingw32-binutils
  • mingw32 (cross compiler)

Want to have the native and cross- packaging for gcc as similar as possible.

• perhaps don't need to mangle the binary names and have things like gcc-defaults
  • but maybe we want to anyway

Use case for build-depending on x-compiler: targeting nolibc (?)

Need/opportunity to refactor/simplify gcc packaging because we want the rules to build the cross compiler and native compiler to be similar.

Current Situation

We currently have binary packages gcc-4.4-source which contain the debianized source tree of the gcc build, but not the dsc. If we provide the .dsc we know that building the package is easier. Need to provide -source packages for build dependencies of the cross compiler, would be nice if they could all be built the same way.

Need to move to using sysroot rather than configuring the cross toolchain at build time and using dpkg -i a lot (?)

Future Direction

sysroot or multiarch?

gcc 4.5 packaging uses sysroot already OpenEmbedded moved to sysroot too

Dependencies:

# download armel toolchain debs to dpkg-cross them
# linux headers
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/l/linux/linux-libc-dev_2.6.32-17.26_armel.deb
# gcc-4.4 runtime lib (eglibc and gmp runtime dep)
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/g/gcc-4.4/libgcc1_4.4.3-4ubuntu4_armel.deb
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/g/gcc-4.4/libstdc++6_4.4.3-4ubuntu4_armel.deb
# eglibc runtime lib and headers
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/e/eglibc/libc6_2.11.1-0ubuntu5_armel.deb
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/e/eglibc/libc6-dev_2.11.1-0ubuntu5_armel.deb
# zlib1g runtime lib and headers (gcc-4.4 build-dep)
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/z/zlib/zlib1g_1.2.3.3.dfsg-15ubuntu1_armel.deb
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/z/zlib/zlib1g-dev_1.2.3.3.dfsg-15ubuntu1_armel.deb
# mpfr runtime lib and headers (gcc-4.4 build-dep)
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/m/mpfr/libmpfr1ldbl_2.4.2-3ubuntu1_armel.deb
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/m/mpfr/libmpfr-dev_2.4.2-3ubuntu1_armel.deb
# gmp runtime lib and headers (mpfr dep)
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/g/gmp/libgmp3c2_4.3.2+dfsg-1ubuntu1_armel.deb
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/g/gmp/libgmpxx4ldbl_4.3.2+dfsg-1ubuntu1_armel.deb
wget http://ports.ubuntu.com/ubuntu-ports/pool/main/g/gmp/libgmp3-dev_4.3.2+dfsg-1ubuntu1_armel.deb

What languages to build cross compilers for?

• demand driven, or keep things equivalent?
• some things easy (obj-c) some things hard (java)
• really only needs C and C++
• could target everything which is in main: C, C++, Fortran

Also see: discussion of how to break build-dependency loops

• https://blueprints.edge.launchpad.net/ubuntu-arm/+spec/arm-m-automated-bootstrap

pbuilder? apt-cross?

Problem looming with gcc runtime libraries between

ACTIONS

• lool to check reverse-build-deps in Debian of the tools source packages, to verify whether they'll be ok to transition to a common approach of shipping full Debian source packages (.dsc) in the binary package
• lool to look into replacing dh_movefiles in the gcc packaging

CategorySpec