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169 lines
5.8 KiB
169 lines
5.8 KiB
Android |
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======= |
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Mesa hardware drivers can be built for Android one of two ways: built |
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into the Android OS using the Android.mk build system on older versions |
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of Android, or out-of-tree using the Meson build system and the |
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Android NDK. |
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The Android.mk build system has proven to be hard to maintain, as one |
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needs a built Android tree to build against, and it has never been |
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tested in CI. The meson build system flow is frequently used by |
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Chrome OS developers for building and testing Android drivers. |
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Building using the Android NDK |
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------------------------------ |
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Download and install the NDK using whatever method you normally would. |
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Then, create your meson cross file to use it, something like this |
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``~/.local/share/meson/cross/android-aarch64`` file:: |
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[binaries] |
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ar = 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-ar' |
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c = ['ccache', 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android29-clang'] |
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cpp = ['ccache', 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android29-clang++', '-fno-exceptions', '-fno-unwind-tables', '-fno-asynchronous-unwind-tables', '-static-libstdc++'] |
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c_ld = 'lld' |
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cpp_ld = 'lld' |
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strip = 'NDKDIR/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android-strip' |
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# Android doesn't come with a pkg-config, but we need one for meson to be happy not |
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# finding all the optional deps it looks for. Use system pkg-config pointing at a |
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# directory we get to populate with any .pc files we want to add for Android |
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pkgconfig = ['env', 'PKG_CONFIG_LIBDIR=NDKDIR/pkgconfig', '/usr/bin/pkg-config'] |
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[host_machine] |
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system = 'linux' |
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cpu_family = 'arm' |
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cpu = 'armv8' |
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endian = 'little' |
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Now, use that cross file for your Android build directory (as in this |
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one cross-compiling the turnip driver for a stock Pixel phone) |
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.. code-block:: console |
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meson build-android-aarch64 \ |
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--cross-file android-aarch64 \ |
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-Dplatforms=android \ |
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-Dplatform-sdk-version=26 \ |
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-Dandroid-stub=true \ |
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-Dgallium-drivers= \ |
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-Dvulkan-drivers=freedreno \ |
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-Dfreedreno-kgsl=true |
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ninja -C build-android-aarch64 |
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Replacing Android drivers on stock Android |
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------------------------------------------ |
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The vendor partition with the drivers is normally mounted from a |
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read-only disk image on ``/vendor``. To be able to replace them for |
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driver development, we need to unlock the device and remount |
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``/vendor`` read/write. |
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.. code-block:: console |
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adb disable-verity |
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adb reboot |
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adb remount -R |
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Now you can replace drivers as in: |
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.. code-block:: console |
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adb push build-android-aarch64/src/freedreno/vulkan/libvulkan_freedreno.so /vendor/lib64/hw/vulkan.sdm710.so |
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Note this command doesn't quite work because libvulkan wants the |
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SONAME to match. For now, in turnip we have been using a hack to the |
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meson.build to change the SONAME. |
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Replacing Android drivers on Chrome OS |
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-------------------------------------- |
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Chrome OS's ARC++ is an Android container with hardware drivers inside |
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of it. The vendor partition with the drivers is normally mounted from |
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a read-only squashfs image on disk. For doing rapid driver |
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development, you don't want to regenerate that image. So, we'll take |
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the existing squashfs image, copy it out on the host, and then use a |
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bind mount instead of a loopback mount so we can update our drivers |
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using scp from outside the container. |
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On your device, you'll want to make ``/`` read-write. ssh in as root |
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and run: |
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.. code-block:: console |
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crossystem dev_boot_signed_only=0 |
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/usr/share/vboot/bin/make_dev_ssd.sh --remove_rootfs_verification --partitions 4 |
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reboot |
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Then, we'll switch Android from using an image for ``/vendor`` to using a |
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bind-mount from a directory we control. |
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.. code-block:: console |
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cd /opt/google/containers/android/ |
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mkdir vendor-ro |
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mount -o loop vendor.raw.img vendor-ro |
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cp -a vendor-ro vendor-rw |
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emacs config.json |
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In the ``config.json``, you want to find the block for ``/vendor`` and |
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change it to:: |
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{ |
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"destination": "/vendor", |
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"type": "bind", |
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"source": "/opt/google/containers/android/vendor-rw", |
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"options": [ |
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"bind", |
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"rw" |
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] |
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}, |
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Now, restart the UI to do a full reload: |
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.. code-block:: console |
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restart ui |
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At this point, your android container is restarted with your new |
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bind-mount ``/vendor``, and if you use ``android-sh`` to shell into it |
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then the ``mount`` command should show:: |
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/dev/root on /vendor type ext2 (rw,seclabel,relatime) |
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Now, replacing your DRI driver with a new one built for Android should |
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be a matter of: |
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.. code-block:: console |
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scp msm_dri.so $HOST:/opt/google/containers/android/vendor-rw/lib64/dri/ |
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You can do your build of your DRI driver using ``emerge-$BOARD |
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arc-mesa-freedreno`` (for example) if you have a source tree with |
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ARC++, but it should also be possible to build using the NDK as |
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described above. There are currently rough edges with this, for |
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example the build will require that you have your arc-libdrm build |
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available to the NDK, assuming you're building anything but the |
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freedreno Vulkan driver for KGSL. You can mostly put things in place |
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with: |
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.. code-block:: console |
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scp $HOST:/opt/google/containers/android/vendor-rw/lib64/libdrm.so \ |
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NDKDIR/sysroot/usr/lib/aarch64-linux-android/lib/ |
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ln -s \ |
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/usr/include/xf86drm.h \ |
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/usr/include/libsync.h \ |
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/usr/include/libdrm \ |
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NDKDIR/sysroot/usr/include/ |
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It seems that new invocations of an application will often reload the |
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DRI driver, but depending on the component you're working on you may |
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find you need to reload the whole Android container. To do so without |
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having to log in to Chrome again every time, you can just kill the |
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container and let it restart: |
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.. code-block:: console |
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kill $(cat /run/containers/android-run_oci/container.pid )
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