Toolchain Roadmap

Status

• Created: Date(2005-04-24T00:11:33Z) by MattZimmermanBR

• Priority: HighPriorityBR

• People: MatthiasKloseLead, JeffBaileySecondBR

• Contributors: MattZimmermanBR

• Interested: JimMcQuillan BR

• Status: BreezyGoal, DistroSpecification, ApprovedSpecification

• Packages: BR

• Depends: BR

• UduSessions: 1(0) BR

Introduction

Review toolchain status and strategy for Breezy

Rationale

• Much improved Java support
• Better error reporting from C and C++ front-end
• LSB 3.0 support
• Fortran 90 support
• Better optimizations from C compiler
• Faster compilation at -O0
• Better standards compliance

Scope and Use Cases

• gcc-4.0
• g++-4.0 and associated ABI transition
• glibc 2.3.5

Implementation Plan

• Details at http://www.ubuntulinux.org/wiki/BreezyToolchainTransition

Already done:

• Change "gcc" default to 4.0
• Change "g77" default to 3.4
• change "cpp" default to 4.0
• Upload glibc-2.3.5
• Change powerpc, ia64 to nptl-only

May TODO:

• Enable ppc64 glibc (ready to upload)
• Upload g++-3.4, building g++ on amd64, defaulting to the new C++ ABI (1002). The current g++-3.4 on amd64 is built for the ABI version 102 to be compatible with g++-3.3 in hoary (libstdc++ having a changed soname).
• Change "g++" default to 4.0
  • Upload library packages, depending on libstdc++, rename library packages to deal with ABI break, as described on the Transition page.
  • For KDE, only rename libqt, as all other KDE packages depend on this library.
  • Upload all other packages depending on libstdc++, just recompiling, and/or applying outstanding bug reports including patches.
• Change "gcj", "gij" default to 4.0
• Add to Breezy release notes intention to drop linuxthreads for remaining arch's.
• Drop gcc-2.95 (also means dropping chill)

Post-May TODO:

• Change sparc to nptl-only
• Look at tweaking gcc wrapper to look for archaic gcc build options (-O6, etc. Possibly do this when HPPA does the Debian import?)
• Binutils update (Sparc64 TLS support)
• Final massive rebuild to make sure that everything is builds correctly.
• Transition for non-release architectures (libgcc on hppa).
• Decide which GCC versions to keep for breezy. GCC-4.0 of course, GCC 3.4 for the default g77 and gpc compilers (which are not part of GCC 4.0). Maybe do not build the java, objc, treelang and ada compilers with from 3.4 (but they go to universe anyway). Decide on GCC 3.3. It's still used for the kernel and glibc. If we want to keep the libstdc++5 for compatibility (well, we have at least for packages like Blackdown Java), keep this version as well, maybe reduce things which are built.

Data Preservation and Migration

glibc update can cause older applications to fail to run. Failures are usually linker-time failures, so low risk of runtime data loss.

Packages Affected

All packages to some degree:

• Poorly written C applications that don't work with stricter parser
• Poorly written C++ applications that don't work with stricter parser
• Renaming of library packages (about 100 in main, 300 in universe)

User Interface Requirements

N/A

Outstanding Issues

Coordinating with Debian - confirm that they will follow the same library rename plan. Proposal sent to debian-release, http://lists.debian.org/debian-release/2005/04/msg00153.html

UDU BOF Agenda

• Status update (some work will be done prior to UDU)
• C++ ABI transition plan (if transitions are still pending)
• libssp and GCC 4.0 ?

UDU Pre-Work

• Transition plan http://www.ubuntulinux.org/wiki/BreezyToolchainTransition

• Prepare packages of GCC-4.0 (currently in experimental), glibc (Done, uploaded)
• PowerPC64 biarch support

• Import of known FTBFS GCC-4.0 reports from unstable, for universe see http://www.ubuntulinux.org/wiki/UniverseCxxTransition (Done)

• Determine order of library updates