Oliver Smith
d13bed7d56
Signed-off-by: Oliver Smith <ollieparanoid@postmarketos.org> Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/8812>
59 lines
3.1 KiB
Markdown
59 lines
3.1 KiB
Markdown
# Firmware Packages
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Firmware (non-free binary blobs, often cryptographically signed by the OEM)
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is nowadays unfortunately required for a lot of essential functionality,
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especially on mobile devices with wireless connectivity or graphics processors.
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## User choice
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While for the longest time, pmbootstrap used to prompt the user whether they
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wanted to install firmware or not, it was decided in early 2024 that nonfree
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firmware would be [installed by
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default](https://postmarketos.org/edge/2024/02/15/default-nonfree-fw/).
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Nonfree firmware dependencies should therefore now be in the `depends` of the
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device package and also not in a separate subpackage. It would technically be
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possible to put it in `_pmb_recommends` as well to allow users to uninstall it
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later, but that is not recommended for the reasons discussed in the blog post.
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Maintainers will have an easier time troubleshooting bug reports if they do not
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need to account for the possibility that the user may have uninstalled required
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firmware dependencies. Any such setup should therefore be considered custom,
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and not something maintainers will generally be able to help with.
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## Packaging
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There are three endorsed methods for providing the nonfree firmware to the
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kernel, in order of preference:
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1. Using firmware files already in `linux-firmware` upstream
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2. Packaging them in pmaports, e.g. a `firmware-vendor-device` package
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3. Reusing the firmware present on a partition on the device
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Firmware files in `linux-firmware` should be preferred if possible and not
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repackaged in pmaports, with exceptions possible to make the installed firmware
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more granular. This is for example done for the Qualcomm Adreno GPU firmware in
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pmaports, which is packaged as `firmware-qcom-adreno-*` and allows device
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packages to depend on their GPU firmware without pulling in the entirety of
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`linux-firmware-qcom`. Similar such packages may be added in the future and
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should be preferred over the larger packages where possible.
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When that is not possible, for example because the vendors did not send the
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firmware upstream, it is recommended to package the firmware files directly in
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pmaports. It prevents potential race conditions between services and greatly
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simplifies the setup, making it easier to reason about what is going on in the
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system. It is also generally considered the most secure alternative. CVEs in
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non-free firmware for things like the modem have existed. Packaging firmware and
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keeping it up-to-date ensures that all users get the newest security patches,
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and do not depend on the Android version they had before installing
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postmarketOS.
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Unfortunately, there are cases where none of the other options are possible, for
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example, when firmware files are specific to the device: unit-specific
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calibration data, region-specific WiFi or modem firmware files, etc. In those
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cases it is reasonable to load the firmware from e.g. the Android partition
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with those files. This can be done using
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[msm-firmware-loader](https://gitlab.postmarketos.org/postmarketOS/msm-firmware-loader),
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which, despite the name, can be modified to suit other devices than just
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Qualcomm-based ones. Extremely space-constrained devices may also use this
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approach if required.
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