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README.md

Project Tuscan

Experiments for evaluating the compilability of a large corpus of programs in various compilation environments:

  • Different C libraries and compilers
  • Different architectures
  • Different platforms
  • Static vs. dynamic linking

Initial setup

Tuscan uses a fork of the libEAR project as a submodule. You will thus need to pass the --recursive switch to the git clone command when cloning Tuscan, or else run git submodule init; git submodule update after you have cloned it.

On the first run, Tuscan will attempt to download a copy of every official Arch Linux binary package, as well as their corresponding sources. These files are placed in the mirror and sources directory, respectively. During the first run, Tuscan will also create and commit an Arch Linux Docker image called tuscan_base_image, whose software databases are in sync with the downloaded sources and binaries. Do not remove this image from your system; if you do, you will need to re-create it and also re-download up-to-date versions of the sources and binaries.

Occasionally, downloads of a source or binary may fail; when this happens for a particular package, a $PACKAGE_NAME.log file will be left in the sources or mirror directory, containing information on the failure.

  • For binaries, you may wish to download the binary yourself and place it in the mirror directory. An archive of all Arch Linux binaries is hosted at the Arch Archive; make sure that the version number that you're downloading matches the version described in the .log file.

  • A failed download of a source file usually indicates that the upstream source is broken. It may be appropriate to file a bug about this on the Arch Linux bug tracker. There is not much that can be done about this; Tuscan will fail to build that package and any packages that depend on it.

Binaries are downloaded from an Arch Linux mirror. If you don't live in the United States, you may wish to replace "United States" in the stages/create_base_image/main.sh script. The invocation of reflector in that script finds the fastest and most up-to-date Arch mirrors from the specified country.

Running Tuscan

Generating data for a toolchain:

./tuscan.py build TOOLCHAIN

The names of toolchains are subdirectories of toolchains/. Currently, the only toolchain is vanilla, which builds Arch Linux packages using the default compiler and standard libraries.

Post-processing the data from a build:

./tuscan.py post

The resulting JSON files are dumped in the output/post/TOOLCHAIN directory, one file per package. The schema for the resulting JSON file is described by the post_processed_schema structure in tuscan/schemata.py.

Generating a HTML report from post-processed data:

./tuscan.py html

The resulting HTML pages are dumped in the output/html/TOOLCHAIN directory, one page per package.

Generating figures from post-processed data:

./tuscan.py figures

The resulting figures are dumped in the output/figures directory.

Structure / Contributing

Tuscan is structured as a set of stages under the stages/ directory. These are scripts that are run inside Arch Linux containers, performing tasks on Arch Linux packages. These tasks include dependency resolution and setting up a build environment for the chosen toolchain.

The final outcome is that every package in the official Arch Linux repository is built with a particular toolchain, in reverse dependency order. Packages that have been built successfully are added to a local package repository, so that packages that depend on them can install them later.

The stages write a makepkg.ninja file that describes dependency relationships between Arch Linux packages.

Some stages depend on other stages having been run before they themselves are run. Some stages also depend on +data-only containers+ having been created. For each experiment, these dependencies are described in the file stages/$STAGE_NAME/deps.yaml.

Dependencies

Software:

Tuscan also requires several Python packages. These can be installed with pip. Tuscan code that runs on your host machine is written in Python 2, so if your operating system uses Python 3 by default you may need to install these packages with pip2.

Troubleshooting

  • Circular dependencies

    If the ninja build for package foo fails because the bar.pkg.tar.xz file could not be found, this is likely due to a circular dependency (foo makedepends on, and is makedepended on by, bar). This can be confirmed by reading the PKGBUILDs for foo and bar: search for these packages on www.archlinux.org/packages, and then browse to the PKGBUILD by clicking on the Source Files link.

    This issue can be fixed by adding foo and bar to the circular_dependency_breakers array in get_base_package_names.

  • Provider packages

    Sometimes foo will depend on bar, but deps_to_ninja will not find any package called bar in the Arch Build Repository. More precisely, there will be no PKGBUILD in the ABS such that the PKGBUILD contains bar in its pkgname array, which would seem to indicate that package bar does not get built by any PKGBUILD.

    In fact, this could be because bar is a metapackage, that is, a package provided by another package baz. An example is sh---many packages depend on sh, but in practice this package is provided by bash. More precisely, the PKGBUILD for bash will contain provides=(... "sh" ...) somewhere in the PKGBUILD.

    The current solution to this is to add "sh" : "bash" to the provides hash in provides.py whenever this causes a problem. These instances are hard to detect automatically because they require parsing the PKGBUILD (a bash script), since the provides array might be hidden inside a package_ function.