105 lines
4.3 KiB
ReStructuredText
105 lines
4.3 KiB
ReStructuredText
Build system
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============
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This page explains internals of the Gluon build system. It is currently very
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incomplete; please contribute if you can!
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Feed management
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---------------
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Rather that relying on the *feed.conf* mechanism of OpenWrt directly, Gluon
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manages its feeds (*"modules"*) using a collection of scripts. This solution was
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selected for multiple reasons:
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- Feeds lists from Gluon base and the site repository are combined
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- Patchsets are applied to downloaded feed repositories automatically
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The following variables specifically affect the feed management:
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GLUON_FEEDS
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List of base feeds; defined in file *modules* in Gluon base
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GLUON_SITE_FEED
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List of site feeds; defined in file *modules* in site config
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\*_REPO, \*_BRANCH, \*_COMMIT
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Git repository URL, branch and
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commit ID of the feeds to use. The branch name may be omitted; the default
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branch will be used in this case.
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GLUON_BASE_FEEDS
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Additional feed definitions to be added to *feeds.conf*
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verbatim. By default, this contains a reference to the Gluon base packages;
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when using the Gluon build system to build a non-Gluon system, the variable
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can be set to the empty string.
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Helper scripts
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--------------
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Several tasks of the build process have been separated from the Makefile into
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external scripts, which are stored in the *scripts* directory. This was done to
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ease maintenance of these scripts and the Makefile, by avoiding a lot of escaping.
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These scripts are either bash or Lua scripts that run on the build system.
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default_feeds.sh
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Defines the constant ``DEFAULT_FEEDS`` with the names of all feeds listed in
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*openwrt/feeds.conf.default*. This script is only used as an include by other
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scripts.
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feeds.sh
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Creates the *openwrt/feeds.conf* file from ``FEEDS`` and ``DEFAULT_FEEDS``. The
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feeds from ``FEEDS`` are linked to the matching subfolder of *packages/* and not
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explicitly defined feeds of ``DEFAULT_FEEDS`` are setup as dummy (src-dummy).
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This *openwrt/feeds.conf* is used to reinstall all packages of all feeds with
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the *openwrt/scripts/feeds* tool.
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modules.sh
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Defines the constants ``GLUON_MODULES`` and ``FEEDS`` by reading the *modules*
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files of the Gluon repository root and the site configuration. The returned
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variables look like:
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- ``FEEDS``: "*feedA feedB ...*"
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- ``GLUON_MODULES``: "*openwrt packages/feedA packages/feedB ...*"
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This script is only used as an include by other scripts.
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patch.sh
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(Re-)applies the patches from the *patches* directory to all ``GLUON_MODULES``
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and checks out the files to the filesystem.
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This is done for each repo by:
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- creating a temporary clone of the repo to patch
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- only branch *base* is used
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- applying all patches via *git am* on top of this temporary *base* branch
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- this branch is named *patched*
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- copying the temporary clone to the *openwrt* (for OpenWrt Base) or
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*packages* (for feeds) folder
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- *git fetch* is used with the temporary clone as source
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- *git checkout* is called to update the filesystem
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- updating all git submodules
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This solution with a temporary clone ensures that the timestamps of checked
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out files are not changed by any intermediate patch steps, but only when
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updating the checkout with the final result. This avoids triggering unnecessary
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rebuilds.
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update.sh
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Sets up a working clone of the ``GLUON_MODULES`` (external repos) from the external
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source and installs it into *packages/* directory. It simply tries to set the *base*
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branch of the cloned repo to the correct commit. If this fails it fetches the
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upstream branch and tries again to set the local *base* branch.
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getversion.sh
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Used to determine the version numbers of the repositories of Gluon and the
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site configuration, to be included in the built firmware images as
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*/lib/gluon/gluon-version* and */lib/gluon/site-version*.
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By default, this uses ``git describe`` to generate a version number based
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on the last git tag. This can be overridden by putting a file called
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*.scmversion* into the root of the respective repositories.
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A command like ``rm -f .scmversion; echo "$(./scripts/getversion.sh .)" > .scmversion``
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can be used before applying local patches to ensure that the reported
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version numbers refer to an upstream commit ID rather than an arbitrary
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local one after ``git am``.
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