Multiarch – a proposal and an implementation

Tollef Fog Heen

tfheen@debian.org

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Tollef Fog Heen <tfheen@debian.org>

Contents

• What is multiarch
• dpkg FeatureDependencies
• Why multiarch
• Why not multiarch
• How to do multiarch
• Current state
• Questions (and hopefully answers)

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Tollef Fog Heen <tfheen@debian.org>

What is multiarch

• Scope
• File system hierarchy
• • /usr/lib/$arch-$os
  • /usr/include/$arch-$os
• Package system implementation

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Tollef Fog Heen <tfheen@debian.org>

dpkg FeatureDependencies

• Depend on features rather than versions

  Build-Depends: debhelper:<dh_installman dh_desktop>

• System-provided packages

  Package: system$

Features: amd64, i386, linux

• dpkg-shlibdeps adds special depends on system$:

  Package: foo

Depends: system$:i386, libc6:i386

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Tollef Fog Heen <tfheen@debian.org>

Why multiarch

• Non-portable programs (Openoffice.org)
• Embedded development/cross-compilation
• Proprietary plugins and software (flash plugins)
• Because we can, it's cool and elegant

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Tollef Fog Heen <tfheen@debian.org>

Why not multiarch

• Complexity
• Core changes needed:
  • dpkg
  • toolchain (gcc, glibc, binutils
  • dak/katie

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Tollef Fog Heen <tfheen@debian.org>

How to do multiarch

• File system layout

  ./configure --prefix=/usr --includedir=/usr/include/$(DEB_HOST_ARCH_CPU)-$(DEB_HOST_ARCH_OS) --libdir=/usr/lib/$(DEB_HOST_ARCH_CPU)-$(DEB_HOST_ARCH_OS)

• Split packages

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Tollef Fog Heen <tfheen@debian.org>

Current status

• In Debian
• Upstream
  • LSB
  • FHS

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Tollef Fog Heen <tfheen@debian.org>

Questions (and answers)

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Tollef Fog Heen <tfheen@debian.org>