9.1.2 Package Transformation Options

Another set of command-line options supported by guix build and also guix package are package transformation options. These are options that make it possible to define package variants—for instance, packages built from different source code. This is a convenient way to create customized packages on the fly without having to type in the definitions of package variants (see Defining Packages).

Package transformation options are preserved across upgrades: guix upgrade attempts to apply transformation options initially used when creating the profile to the upgraded packages.

The available options are listed below. Most commands support them and also support a --help-transform option that lists all the available options and a synopsis (these options are not shown in the --help output for brevity).

--tune[=cpu]

Use versions of the packages marked as “tunable” optimized for cpu. When cpu is native, or when it is omitted, tune for the CPU on which the guix command is running.

Valid cpu names are those recognized by the underlying compiler, by default the GNU Compiler Collection. On x86_64 processors, this includes CPU names such as nehalem, haswell, and skylake (see -march in Using the GNU Compiler Collection (GCC)).

As new generations of CPUs come out, they augment the standard instruction set architecture (ISA) with additional instructions, in particular instructions for single-instruction/multiple-data (SIMD) parallel processing. For example, while Core2 and Skylake CPUs both implement the x86_64 ISA, only the latter supports AVX2 SIMD instructions.

The primary gain one can expect from --tune is for programs that can make use of those SIMD capabilities and that do not already have a mechanism to select the right optimized code at run time. Packages that have the tunable? property set are considered tunable packages by the --tune option; a package definition with the property set looks like this:

(package
  (name "hello-simd")
  ;; ...

  ;; This package may benefit from SIMD extensions so
  ;; mark it as "tunable".
  (properties '((tunable? . #t))))

Other packages are not considered tunable. This allows Guix to use generic binaries in the cases where tuning for a specific CPU is unlikely to provide any gain.

Tuned packages are built with -march=CPU; under the hood, the -march option is passed to the actual wrapper by a compiler wrapper. Since the build machine may not be able to run code for the target CPU micro-architecture, the test suite is not run when building a tuned package.

To reduce rebuilds to the minimum, tuned packages are grafted onto packages that depend on them (see grafts). Thus, using --no-grafts cancels the effect of --tune.

We call this technique package multi-versioning: several variants of tunable packages may be built, one for each CPU variant. It is the coarse-grain counterpart of function multi-versioning as implemented by the GNU tool chain (see Function Multiversioning in Using the GNU Compiler Collection (GCC)).

--with-source=source

--with-source=package=source

--with-source=package@version=source

Use source as the source of package, and version as its version number. source must be a file name or a URL, as for guix download (see Invoking guix download).

When package is omitted, it is taken to be the package name specified on the command line that matches the base of source—e.g., if source is /src/guile-2.0.10.tar.gz, the corresponding package is guile.

Likewise, when version is omitted, the version string is inferred from source; in the previous example, it is 2.0.10.

This option allows users to try out versions of packages other than the one provided by the distribution. The example below downloads ed-1.7.tar.gz from a GNU mirror and uses that as the source for the ed package:

guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz

As a developer, --with-source makes it easy to test release candidates:

guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz

… or to build from a checkout in a pristine environment:

$ git clone git://git.sv.gnu.org/guix.git
$ guix build guix --with-source=guix@1.0=./guix

--with-input=package=replacement

Replace dependency on package by a dependency on replacement. package must be a package name, and replacement must be a package specification such as guile or guile@1.8.

For instance, the following command builds Guix, but replaces its dependency on the current stable version of Guile with a dependency on the legacy version of Guile, guile@2.0:

guix build --with-input=guile=guile@2.0 guix

This is a recursive, deep replacement. So in this example, both guix and its dependency guile-json (which also depends on guile) get rebuilt against guile@2.0.

This is implemented using the package-input-rewriting Scheme procedure (see package-input-rewriting).

--with-graft=package=replacement

This is similar to --with-input but with an important difference: instead of rebuilding the whole dependency chain, replacement is built and then grafted onto the binaries that were initially referring to package. See Security Updates, for more information on grafts.

For example, the command below grafts version 3.5.4 of GnuTLS onto Wget and all its dependencies, replacing references to the version of GnuTLS they currently refer to:

guix build --with-graft=gnutls=gnutls@3.5.4 wget

This has the advantage of being much faster than rebuilding everything. But there is a caveat: it works if and only if package and replacement are strictly compatible—for example, if they provide a library, the application binary interface (ABI) of those libraries must be compatible. If replacement is somehow incompatible with package, then the resulting package may be unusable. Use with care!

--with-debug-info=package

Build package in a way that preserves its debugging info and graft it onto packages that depend on it. This is useful if package does not already provide debugging info as a debug output (see Installing Debugging Files).

For example, suppose you’re experiencing a crash in Inkscape and would like to see what’s up in GLib, a library deep down in Inkscape’s dependency graph. GLib lacks a debug output, so debugging is tough. Fortunately, you rebuild GLib with debugging info and tack it on Inkscape:

guix install inkscape --with-debug-info=glib

Only GLib needs to be recompiled so this takes a reasonable amount of time. See Installing Debugging Files, for more info.

Note: Under the hood, this option works by passing the ‘#:strip-binaries? #f’ to the build system of the package of interest (see Build Systems). Most build systems support that option but some do not. In that case, an error is raised.

Likewise, if a C/C++ package is built without -g (which is rarely the case), debugging info will remain unavailable even when #:strip-binaries? is false.

--with-c-toolchain=package=toolchain

This option changes the compilation of package and everything that depends on it so that they get built with toolchain instead of the default GNU tool chain for C/C++.

Consider this example:

guix build octave-cli \
  --with-c-toolchain=fftw=gcc-toolchain@10 \
  --with-c-toolchain=fftwf=gcc-toolchain@10

The command above builds a variant of the fftw and fftwf packages using version 10 of gcc-toolchain instead of the default tool chain, and then builds a variant of the GNU Octave command-line interface using them. GNU Octave itself is also built with gcc-toolchain@10.

This other example builds the Hardware Locality (hwloc) library and its dependents up to intel-mpi-benchmarks with the Clang C compiler:

guix build --with-c-toolchain=hwloc=clang-toolchain \
           intel-mpi-benchmarks

Note: There can be application binary interface (ABI) incompatibilities among tool chains. This is particularly true of the C++ standard library and run-time support libraries such as that of OpenMP. By rebuilding all dependents with the same tool chain, --with-c-toolchain minimizes the risks of incompatibility but cannot entirely eliminate them. Choose package wisely.

--with-git-url=package=url

Build package from the latest commit of the master branch of the Git repository at url. Git sub-modules of the repository are fetched, recursively.

For example, the following command builds the NumPy Python library against the latest commit of the master branch of Python itself:

guix build python-numpy \
  --with-git-url=python=https://github.com/python/cpython

This option can also be combined with --with-branch or --with-commit (see below).

Obviously, since it uses the latest commit of the given branch, the result of such a command varies over time. Nevertheless it is a convenient way to rebuild entire software stacks against the latest commit of one or more packages. This is particularly useful in the context of continuous integration (CI).

Checkouts are kept in a cache under ~/.cache/guix/checkouts to speed up consecutive accesses to the same repository. You may want to clean it up once in a while to save disk space.

--with-branch=package=branch

Build package from the latest commit of branch. If the source field of package is an origin with the git-fetch method (see origin Reference) or a git-checkout object, the repository URL is taken from that source. Otherwise you have to use --with-git-url to specify the URL of the Git repository.

For instance, the following command builds guile-sqlite3 from the latest commit of its master branch, and then builds guix (which depends on it) and cuirass (which depends on guix) against this specific guile-sqlite3 build:

guix build --with-branch=guile-sqlite3=master cuirass

--with-commit=package=commit

This is similar to --with-branch, except that it builds from commit rather than the tip of a branch. commit must be a valid Git commit SHA1 identifier, a tag, or a git describe style identifier such as 1.0-3-gabc123.

--with-patch=package=file

Add file to the list of patches applied to package, where package is a spec such as python@3.8 or glibc. file must contain a patch; it is applied with the flags specified in the origin of package (see origin Reference), which by default includes -p1 (see patch Directories in Comparing and Merging Files).

As an example, the command below rebuilds Coreutils with the GNU C Library (glibc) patched with the given patch:

guix build coreutils --with-patch=glibc=./glibc-frob.patch

In this example, glibc itself as well as everything that leads to Coreutils in the dependency graph is rebuilt.

--with-latest=package

So you like living on the bleeding edge? This option is for you! It replaces occurrences of package in the dependency graph with its latest upstream version, as reported by guix refresh (see Invoking guix refresh).

It does so by determining the latest upstream release of package (if possible), downloading it, and authenticating it if it comes with an OpenPGP signature.

As an example, the command below builds Guix against the latest version of Guile-JSON:

guix build guix --with-latest=guile-json

There are limitations. First, in cases where the tool cannot or does not know how to authenticate source code, you are at risk of running malicious code; a warning is emitted in this case. Second, this option simply changes the source used in the existing package definitions, which is not always sufficient: there might be additional dependencies that need to be added, patches to apply, and more generally the quality assurance work that Guix developers normally do will be missing.

You’ve been warned! In all the other cases, it’s a snappy way to stay on top. We encourage you to submit patches updating the actual package definitions once you have successfully tested an upgrade (see Contributing).

--without-tests=package

Build package without running its tests. This can be useful in situations where you want to skip the lengthy test suite of a intermediate package, or if a package’s test suite fails in a non-deterministic fashion. It should be used with care because running the test suite is a good way to ensure a package is working as intended.

Turning off tests leads to a different store item. Consequently, when using this option, anything that depends on package must be rebuilt, as in this example:

guix install --without-tests=python python-notebook

The command above installs python-notebook on top of python built without running its test suite. To do so, it also rebuilds everything that depends on python, including python-notebook itself.

Internally, --without-tests relies on changing the #:tests? option of a package’s check phase (see Build Systems). Note that some packages use a customized check phase that does not respect a #:tests? #f setting. Therefore, --without-tests has no effect on these packages.

Wondering how to achieve the same effect using Scheme code, for example in your manifest, or how to write your own package transformation? See Defining Package Variants, for an overview of the programming interfaces available.