Compiling fluoride bluetooth stack for embedded linux - bluetooth

Question

Has anyone been able to compile fluoride bluetooth stack separately for an embedded linux device?
There is a guide at https://android.googlesource.com/platform/system/bt/+/181144a50114c824cfe3cdfd695c11a074673a5e/README.md, but following these instructions gn gen fails without getting the common-mk folder and modding some build files so there are no missing variables, folders etc.
I have been able to generate Ninja files, but when building, there are missing gtest and modp_b64 headers. After getting them from Google's source search, Ninja seems to be able to run a bit without errors, but ultimately fails with:
In file included from ../../third_party/libchrome/base/message_loop/message_loop.h:18:
../../third_party/libchrome/base/message_loop/message_loop_current.h:209:3: error: static_assert failed due to requirement 'std::is_same<MessagePumpForUI, MessagePumpLibevent>::value' "MessageLoopCurrentForUI::WatchFileDescriptor is not supported when MessagePumpForUI is not a MessagePumpLibevent."
static_assert(std::is_same<MessagePumpForUI, MessagePumpLibevent>::value,
^ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
../../third_party/libchrome/base/message_loop/message_loop_current.h:214:28: error: no type named 'Mode' in 'base::MessagePumpGlib'; did you mean 'MessagePumpLibevent::Mode'?
MessagePumpForUI::Mode mode,
^~~~~~~~~~~~~~~~~~~~~~
MessagePumpLibevent::Mode
../../third_party/libchrome/base/message_loop/watchable_io_message_pump_posix.h:55:8: note: 'MessagePumpLibevent::Mode' declared here
enum Mode {
^
In file included from ../../third_party/libchrome/base/run_loop.cc:10:
In file included from ../../third_party/libchrome/base/message_loop/message_loop.h:18:
../../third_party/libchrome/base/message_loop/message_loop_current.h:215:28: error: no type named 'FdWatchController' in 'base::MessagePumpGlib'; did you mean 'MessagePumpLibevent::FdWatchController'?
MessagePumpForUI::FdWatchController* controller,
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
MessagePumpLibevent::FdWatchController
../../third_party/libchrome/base/message_loop/message_pump_libevent.h:28:9: note: 'MessagePumpLibevent::FdWatchController' declared here
class FdWatchController : public FdWatchControllerInterface {
^
In file included from ../../third_party/libchrome/base/run_loop.cc:10:
In file included from ../../third_party/libchrome/base/message_loop/message_loop.h:18:
../../third_party/libchrome/base/message_loop/message_loop_current.h:216:28: error: no type named 'FdWatcher' in 'base::MessagePumpGlib'; did you mean 'MessagePumpLibevent::FdWatcher'?
MessagePumpForUI::FdWatcher* delegate);
^~~~~~~~~~~~~~~~~~~~~~~~~~~
MessagePumpLibevent::FdWatcher
../../third_party/libchrome/base/message_loop/watchable_io_message_pump_posix.h:17:9: note: 'MessagePumpLibevent::FdWatcher' declared here
class FdWatcher {
^
4 errors generated.
All the errors and missing files are coming from third_party/libchrome
Any help would be much appreciated.

Answer 1

I followed instructions at https://cs.android.com/android/platform/superproject/+/master:system/bt/README.md
In addition to instructions there, I had to resolve issues in the build script manually. I was able to compile the bluetooth stack successfully in Ubuntu 21.04
Replace //bt with /home/udara/fluoride/bt in build files.
Used sed command. Change to your fluoride directory as appropriate.
for file in $(grep -r -l "//bt"); do sed -i 's/\/\/bt/\/home\/udara\/fluoride\/bt/g' $file; done
Copied common-mk symlink generated by bootstrap.py to the fluoride directory.
And replaced //common-mk with /home/udara/fluoride/common-mk.
for file in $(grep -r -l "//common-mk"); do sed -i 's/\/\/common-mk/\/home\/udara\/fluoride\/common-mk/g' $file; done
Installed few missing dependencies
sudo apt install llvm
sudo apt install libc++abi-dev
Copied /home/udara/fluoride/bt/output/out/Default/gen/ABS_PATH/home/udara/fluoride/bt/gd/dumpsys/bundler/bundler_generated.h to /home/udara/fluoride/bt/gd/dumpsys/
cp /home/udara/fluoride/bt/output/out/Default/gen/ABS_PATH/home/udara/fluoride/bt/gd/dumpsys/bundler/bundler_generated.h /home/udara/fluoride/bt/gd/dumpsys/
Created directory named output in the bt directory.
Set environment variables
# this is set by bootstrap.py
export STAGING_DIR=/home/udara/fluoride/staging
# you have to manually set this
export OUTPUT_DIR=/home/udara/fluoride/bt/output
Then compile the bluetooth stack with
./build.py --output ${OUTPUT_DIR} --platform-dir ${STAGING_DIR} --clang
Add the following lines to /etc/dbus-1/system.d/bluetooth.conf
<policy>
...
<allow own="org.chromium.bluetooth"/>
<allow own="org.chromium.bluetooth.Manager"/>
</policy>
Finally run fluoride with
cd /home/udara/fluoride/bt/output/debug
sudo ./btadapterd --hci=0 INIT_gd_hci=true

Answer 2

The reason the common-mk issues are coming up because between the instructions being written, and now, libchrome has added a BUILD.gn file - so it is being used, instead of the substitute one in build/secondary/third-party/libchrome as intended. To fix this part of the build, just delete third-party/libchrome/BUILD.gn - should prevent the need for a lot of build fiddling.
The second part is because of the configuration of libchrome. Once you remove the file mentioned, then you need to modify build/secondary/third-party/libchrome/BUILD.gn to add the following not just to the source_set (as is done in upstream) but also to libchrome_config for downstream users:
defines = [
"__ANDROID_HOST__=1",
]
This will affect the build config so it doesn't try to use glib.
My best work on getting this to build is here, though I haven't gotten it to work entirely. https://github.com/rpavlik/fluoride I did this mostly as an experiment, feel free to continue where I left off.