[llvmlinux] LLVMLinux Meeting 2013-06-20

Behan Webster behanw at converseincode.com
Sun Jun 23 00:48:28 UTC 2013


*

LLVMLinux Project: http://llvm.linuxfoundation.org/


<http://llvm.linuxfoundation.org/>

This week the meeting was on Thursday, June 20 2013 on Google Plus
Hangout at 14:00 UTC

(16:00 in Germany, 15:00 in England, 11:00 in Brazil, 10:00 EDT, 700
PDT)<https://www.google.com/calendar/embed?src=su5vu85fj58ncfrgalmq4vbbf0%40group.calendar.google.com&ctz=GMT>


<https://www.google.com/calendar/embed?src=su5vu85fj58ncfrgalmq4vbbf0%40group.calendar.google.com&ctz=GMT>


If you haven't use G+ Hangouts before, make sure you have the
appropriate Chrome or Firefox plugin installed, and tested before the
time of the meeting. You can try a test hangout with me today before the
meeting if you want to. G+ recently changed, so hopefully that won't be
an issue for our meeting.


-------------------------------------------------------------------------------------------------------------------------

Previous meeting's top 2-3 work items:

  *

    This is what people said they'd be working on at the end of the last
    meeting:

      o

        Behan

          +

            Kernel patches

              #

                Thinkpad nested function patch

              #

                ARM named register patches

              #

                mm-hugepage patch

          +

            VLAIS article

          +

            LLVM micro conference

      o

        Jan-Simon:

          +

            patches:

              #

                0001-updates-to-latest-patchset-unsplit.-TODO.patch

              #

                0028-Misc-changes-to-arch-x86-kernel-to-compile-with-clan.patch

              #

                0033-Various-fixes-in-arch-x86-include-asm.patch

          +

            x86 target test (prepare better testing for debugging
            section on qemu)

      o

        Vinicius

          +

            Add targets llvmlinux-patch-triage - postponed

              #

                nexus7 target - partial done

              #

                rpi target - done

          +

            Fix Nexus 7 build - partial done

          +

            Add U-Boot target - postponed

      o

        Eduard

          +

            Create documentation on checker wrapper arch + integration
            methods

          +

            Dissect build-scan

              #

                Start integrating into buildbot OR

              #

                Extract relevant bits and create custom extension to
                buildbot

-------------------------------------------------------------------------------------------------------------------------

Agenda for this week:


  *

    (5 mins total) Everyone shared a quick summary of the progress
    they've made from the last 4 weeks

      o

        Behan

          +

            Kernel patches:

          +

            Worked on LLVM uConference for LPC (more below)

          +

            Worked on BeagleBone

      o

        Bernhard

          +

            daily LLVM+clang builds for both trunk and 3.3 branch

          +

            https://snapshots.linaro.org/components/toolchain

          +

            Android is now building with some patches, but it's not booting

      o

        Tinti

          +

            Add targets llvmlinux-patch-triage - postpone

              #

                nexus7 target - partial done

                  *

                    strexd -> no problem

                  *

                    ldrexd -> problem!

              #

                rpi target - done

          +

            Fix Nexus 7 build - partial done

          +

            Add U-Boot target - postponed

      o

        Mark

          +

            Been sidelined for a couple weeks on other projects at work

          +

            Had started unifying VLAIS patches but never finished them all

      o

        Eduard

          +

            Buildbot integration postponed

          +

            Worked on patch to ML to run checker using our buildsystem

      o

        Randy

          +

            build oe-core native tools using clang. elf-utils fork bombs
            the builder.

          +

            ongoing work to fix this as time permits.

          +

            This is a hacky approach, what's really needed is changes to
            the oe-core code to allow alternative toolchains. I may
            switch to that approach but it'll be a long learning curve.
            see: https://github.com/m0use/elfutils-clang-patches

      o

        Renato

          +

            Only LLVM dev at Linaro (Randy asks if there's anyone on
            call that can influence Linaro? :)  ) Bero?

      o

        Jan-Simon

          +

            Discussed inline BTC patch with PaxTeam

          +

            Upstreaming kernel patches


(45 mins) General meeting discussions:

      o

        Linaro support of LLVMLinux

          +

            Renato would like to help out more with the LLVMLinux
            project. However without Linaro members indicating that a
            clang compiled Linux Kernel is important to them, his hands
            are tied.

          +

            If you know a Linaro member company who uses LLVM/clang,
            encourage them to ask Linaro for a clang compiled kernel

      o

        LLVM update (current wish list)

          +

            Fix for dropped symbol attributes like  __init and __exit
            (likely the case of the segmentation mismatch/merged global
            issues)

          +

            Add support for extra braces in asm (needed in x86_64 build asm)

      o

        Kernel Patch triage (highest priority now)

          +

            The best way to participate in upstreaming patches is with
            the following spreadsheet. Ask for access if you want to be
            able to update it

          +

            https://docs.google.com/spreadsheet/ccc?key=0Ao2VHhaw1DTqdERLUDBmVlpiY2pUNUlLa1k3ck1Zc1E#gid=0

          +

            Spreadsheet integrates with "make kernel-patch-status" in
            LLVMLinux build

          +

            More patches sent upstream by Jan-Simon and Behan

          +

            Time is being spent figuring out whether existing patches
            can be upstreamed

          +

            Waiting for feedback on some patches

          +

            Have resubmitted some patches more than once. No replies
            (for instance the Thinkpad ACPI nest functions patch)

      o

        VLAIS update

          +

            Went back to USB gadget developers. Seems they're not doing
            the work. They were making suggestions about how we should
            rewrite our patch. We need to rewrite this. Mark volunteered.

          +

            Behan hasn't had time to finish the VLAIS article yet.

      o

        Merged globals/section mismatches update

          +

            Jan-Simon has test case for dropped attribute in clang, will
            put in LLVM bug tracker

          +

            Still needs more investigation

          +

            Investigation so far
            https://lftraining.dyndns.org/pad/p/llvm-section-mismatch

          +

            These dropped attributes mess up where init and exit code is
            linked which is causing the section mismatches

      o

        Tools

          +

            Clang Static Analyzer

              #

                Demo checker run:
                http://buildbot.llvm.linuxfoundation.org/2013-06-17-1/

              #

                Still full of false positives. Will publish more widely
                when it's less noisy (Eduard is working on removing
                checkers which are useless to the kernel code base)

              #

                A current x86_64 checker build takes about 4 hours on
                Eduard's laptop

              #

                Some changes are needed for the LLVMLinux build system

              #

                Still having issues with ARM cross compile with static
                analyzer (but this will work eventually.)

              #

                Adding an optional buildbot build of the kernel with checker

              #

                Disable some checks (which are only valid for user space)

              #

                Write custom checks for the Kernel

                  *

                    Can get ideas from other analysers (coccinelle,
                    smatch, sparse)

                  *

                    Marcelo suggested looking here
                    http://dl.acm.org/citation.cfm?id=1950401

      o

        Raspberry Pi Update

          +

            Building and booting again (was broken recently)

          +

            USB hub driver is still broken

      o

        Cubieboard

          +

            forward ported patchset (cubieboard overlay)

      o

        LLVM micro conference at Linux Plumbers Conference

          +

            Mark and Behan were asked to lead the LLVM Micro-conference
            at Linux Plumbers Conference
            http://wiki.linuxplumbersconf.org/2013:llvm

          +

            http://www.linuxplumbersconf.org/2013/submitting-topic/

      o

        LLVMLinux social media

          +

            LLVMLinux Community on G+
            https://plus.google.com/u/0/communities/112779045358462609379

      o

        Review bug list (please update your bugs on the website before
        the meeting)

          +

            No change this week

      o

        Review todo/roadmap list  (please update your todos on the
        website before the meeting)

          +

            No change this week

      o

        Review the project Roadmap/Timeline

          +

            https://docs.google.com/a/converseincode.com/spreadsheet/ccc?key=0AoeRmB6JBVt_dGYwSUNNNHd2SFFMWF9yMTRoa2VuZmc#gid=0

      o

  *

    (5 mins) Each meeting attendee listed the top 2 items to be worked
    on for the next 2 weeks

      o

        Behan

          +

            Upstream kernel patches

          +

            VLAIS article

      o

        Jan-Simon

          +

            follow up on btc with kernel devs to find out what we can

          +

            section issue

          +

            more patches upstream

      o

        Eduard

          +

            Integration with llvmlinux build-system

          +

            Select checkers to a) run and b) modify to reduce number of
            false positives

      o

        Randy

          +

            oe-core build

      o

        Mark

          +

            Getting married. :)

      o

        Tinti

          +

            Add Nexus 7, Nexus 4 and Raspberry Pi to patch triage

          +

            Upstream Nexus 7 issue (ldrexd)

          +

            Add GDB tutorial on Wiki

          +

            Add KGDB tutorial on Wiki

          +

            Add U-Boot


Next meeting in 2-ish weeks. doodle poll to follow.

*

-- 
Behan Webster
behanw at converseincode.com

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