Debug builds for the Flame, and also ASan, Valgrind builds

[Gary Kwong]

Hi all,

Currently our builds using Mozilla-TWQA's B2G Flash Tool [1] flash only
opt builds.

How useful do developers think it would be to have debug eng builds as
well? [2] This will enable assertions and probably make it easier to
debug gaia-ui-tests, as well as look out for seccomp violations.

Also, it would be nice to have ASan support [3] for Firefox OS to help
find security issues. That being said, Valgrind support is underway, but
I could find some work at Github [4] from some months back.

-Gary

[1] https://github.com/Mozilla-TWQA/B2G-flash-tool
[2] https://bugzilla.mozilla.org/show_bug.cgi?id=1039053
[3] https://bugzilla.mozilla.org/show_bug.cgi?id=1039056
[4] https://github.com/mozilla-b2g/valgrind

[Kyle Huey]

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I've been using a debug build on my Nexus 5 for a few days now and
it's surprisingly stable.

Not sure how useful the builds are to people without symbols though.

- Kyle

[Kyle Machulis]

We've had FxOS valgrind support for over a year, though it does require me manually updating the repo (which I'm hoping to do this week). However, that was only for the Nexus 4/5 because they were the only things with enough RAM. The new valgrind work on the flame is happening because (from my understanding) we have more control over the kernel and therefore can possibly operate in 1gb.

[Eric Rahm]

I managed to run valgrind on my Flame while looking into DMD issues
without doing anything particularly special.

-e

[Eric Rahm]

I've been using them recently as well. It would definitely be nice if we
provided builds, but as Kyle noted we should probably provide the
symbols as well.

+1 for ASan (and it's buddy LSan). I believe we'll need to update to a
newer version of GCC (support was added in 4.8.0) to be able to enable
it. I seem to recall a discussion about using a more modern GCC, but I'm
not sure what came of that.

-e

[Gary Kwong]

> +1 for ASan (and it's buddy LSan).

What's the status of MSan? (the 3rd buddy) Is there any work on that for
Desktop Firefox as well? Would it also be useful for Firefox OS?

-Gary

[Eric Rahm]

My understanding is MSan is llvm, linux x86_64 only, generally making it
a no-go 3 different ways. It claims to be a subset of Valgrind's
memcheck, so in theory we should get more coverage from valgrind
(although with a much greater slow down).

-e