[lttng-dev] Port to Android Linux

[Harald Gustafsson]

Hi all,
> Did anyone successfully port LTTng to Android Linux?

Yes, we (Ericsson) have ported UST to Android and we have a fully
working but a bit rough code for it. It uses URCU and UST, we have
used it to trace for example pthread_mutex operation by LD_PRELOAD a
wrapper to bionic and hence it can handle that kind of load of traces.
A few weeks back I got clearance for contributing this back to LTTng
but I have not yet had time to upload, I will do that during the week.

The rough part is the reimplementation of System V shared memory, we
use temporary files, this was a quick fix since using binder and ashm
would had involved larger changes to UST. The URCU changes are similar
to what Marek Vavrusa mailed (22th Jan) about URCU thread local
storage handling, this is needed since gcc with bionics can't do the
__thread. Also since the code we forked in May did not have proper
atomics for ARM we fixed that as well. One part can't be released it
is our trace clock implementation since it is device specific, but
since we tested on a pre-production system we did not need to be
concerned about security. We implemented the trace-clock by mmap the
memory (/dev/mem) having the device's clock-register and code read
that from user space directly.

So I'll get back with a patch when I cleaned the code a bit.
Unfortunately, we don't have that much time to maintain this but would
gladly help anyone wanting to work with the code.

/Harald