015a8b82b8
R=thestig@chromium.org Change-Id: I573a16b6ec61615c5e165c4c2476ac0e3362db51 Reviewed-on: https://chromium-review.googlesource.com/767615 Reviewed-by: Lei Zhang <thestig@chromium.org> Commit-Queue: Thomas Anderson <thomasanderson@chromium.org> Cr-Commit-Position: refs/heads/master@{#516505}
87 lines
3.4 KiB
Markdown
87 lines
3.4 KiB
Markdown
# Linux sysroot images
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The chromium build system for Linux will (by default) use a sysroot image
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rather than building against the libraries installed on the host system.
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This serves several purposes. Firstly, it ensures that binaries will run on all
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supported linux systems independent of the packages installed on the build
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machine. Secondly, it makes the build more hermetic, preventing issues that
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arise for variations among developers' systems.
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The sysroot consists of a minimal installation of Debian/stable (or old-stable)
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to ensure maximum compatibility. Pre-built sysroot images are stored in
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Google Cloud Storage and downloaded during `gclient runhooks`
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## Installing the sysroot images
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Installation of the sysroot is performed by
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`build/linux/sysroot_scripts/install-sysroot.py`.
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This script can be run manually but is normally run as part of gclient
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hooks. When run from hooks this script in a no-op on non-linux platforms.
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## Rebuilding the sysroot image
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The pre-built sysroot images occasionally needs to be rebuilt. For example,
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when security updates to Debian are released, or when a new package is needed by
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the chromium build. If you just want to update the sysroots without adding any
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new packages, skip to `Using build_and_upload.py`.
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### Adding new packages
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To add a new package, edit the `sysroot-creator-*.sh` scripts and modify the
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`DEBIAN_PACKAGES` list, then run the update step (`UpdatePackageListsAll`). The
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steps below will use `sysroot-creator-stretch.sh` as an example.
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### Updating existing package list
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To update packages to the latest versions run:
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$ ./sysroot-creator-stretch.sh UpdatePackageListsAll
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This command will update the package lists that are stored alongside the script.
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If no packages have changed then this script will have no effect.
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### Rebuilding
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To rebuild the images (without any changes) run the following commands:
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$ cd build/linux/sysroot_scripts
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$ ./sysroot-creator-stretch.sh BuildSysrootAll
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The above command will rebuild the sysroot for all architectures. To build
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just one architecture use `BuildSysroot<arch>`. Run the script with no
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arguments for a list of possible architectures. For example:
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$ ./sysroot-creator-stretch.sh BuildSysrootAmd64
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This command on its own should be a no-op and produce an image identical to
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the one on Google Cloud Storage.
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### Uploading new images
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To upload images to Google Cloud Storage run the following command:
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$ ./sysroot-creator-stretch.sh UploadSysrootAll <SHA1>
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Here you should use the SHA1 of the git revision at which the images were
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created.
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Uploading new images to Google Clound Storage requires write permission on the
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`chrome-linux-sysroot` bucket.
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### Rolling the sysroot version used by chromium
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Once new images have been uploaded, the `sysroots.json` file needs to be updated
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to reference the new versions. This process is manual and involves updating the
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`Revision` and `Sha1Sum` values in the file.
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### Using `build-and-upload.py`
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The `build_and_upload.py` script automates the above four steps. It is
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recommended to use this just before you're ready to submit your CL, after you've
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already tested one of the updated sysroots on your local configuration. Build
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or upload failures will not produce detailed output, but will list the script
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and arguments that caused the failure. To debug this, you must run the failing
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command manually. This script requires Google Cloud Storage write permission on
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the `chrome-linux-sysroot` bucket.
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