[llvmlinux] LLVMLinux Meeting Minutes 2013-06-05

Behan Webster behanw at converseincode.com
Sat Jun 8 02:59:44 UTC 2013


*

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


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

*This week the meeting was on Thursday, June 5 2013 on Google Plus
Hangout at *5*pm
UTC**<https://www.google.com/calendar/embed?src=su5vu85fj58ncfrgalmq4vbbf0%40group.calendar.google.com&ctz=GMT>*


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

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

        Bero:

          +

            Clean up Android userspace from Clang port

          +

            Send wrapper to JSM

              #

                http://git.linaro.org/git-ro/people/bernhardrosenkranzer/clang-wrapper.git

              #

                https://snapshots.linaro.org/components/toolchain/bero-test-llvm/latest

      o

        Jan-Simon:

          +

            Patch split and more upstreaming  (OOO and teaching)

      o

        Vicinius:

          +

            Finish CTS tests with AOSP.

              #

                Nexus 7 target is broken.

          +

            VLAIS benchmark for the LPC.

              #

                Not worked.

      o

        Behan:

          +

            VLAIS graphs and article

          +

            upstreaming kernel patches

          +

            LPC uConference planning

          +

            Asking the kernel community about checkers

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

Minutes for this week:


  *

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

      o

        Behan

          +

            Started VLAIS article

          +

            Kernel patches:

              #

                Removed patches which made it upstream (osx acpi patch)

              #

                Removed patches which are no longer required (ENUM bit
                fields)

              #

                Reworked patches ready for upstreaming (named register
                for ARM)

          +

            Wrote tool to better manage patch upstreaming (patchstatus)

          +

            Worked on LLVM uConference for LPC (more below)

          +

            GSoC setup

      o

        Jan-Simon

          +

            OOO + teaching

          +

            Discussed a few patches with pipacs, we can drop one for sure.

          +

            Split + cleanup patches more

          +

            x86 test target rework

      o

        Vinicius

          +

            rpi 3.8 kernel work.

          +

            Trying to fix issues with Nexus 7 target.

      o

        Eduard

          +

            Reading documentation on Clang/LLVM and the static analyzer

          +

            Getting ready for the start of work on June 17th

(45 mins) General meeting discussions:

      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 named registers support to clang

              #

                e.g: register unsigned long current_sp asm ("sp");

          +

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

          +

            Add support to Integrated Assembler to work with the
            existing ASM in the kernel code

          +

            x86_64 BTR/BTS inline assembly instruction size issue in
            unified code

      o

        Kernel Patch triage (highest priority now)

          +

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

          +

            Now accessible per target via tools/patchstatus script (demo)

          +

            Patch statuses:

              #

                Archived (sent to relevant bug tracker, but otherwise
                archive patch which isn't immediately necessary to
                accomplish project goals)

              #

                Trivial (simple patches to upstream quickly)

              #

                Clang + KBuild (patches which are specific to clang.
                Will likely be upstreamed last)

              #

                VLAIS (Variable Length Arrays In Struct code)

              #

                Split/Cleanup (Patches which need further work or
                splitting up and documenting)

              #

                Investigation needed (need further input from other
                experts or maintainers)

      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.

          +

            Behan started the VLAIS article.

      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

        U-boot

          +

            The guys from U-boot are interested in adding Clang support
            to the U-boot code base

          +

            They seem to be able to use LLVM 3.2 just fine

          +

            Vinicius will integrate U-boot into the build

      o

        Tools

          +

            Clang Static Analyzer

              #

                Adding an optional 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

              #

                Integrate into the project buildbot

              #

                Keep static analyzer output for each build on the buildbot

          +

            Marcelo's tool

              #

                Analyzing LLVMIR of the kernel (x86)

              #

                Another static analysis tool for looking at memory types

              #

                Most interested atomicity which is largely in the inline
                ASM at the moment

      o

        Raspberry Pi Update

          +

            Nothing new.

      o

        Cubieboard

          +

            Nothing new.

      o

        GSoC

          +

            http://llvm.linuxfoundation.org/index.php/GSoC

          +

            Eduard's proposal was accepted. He will be our GSoC student
            for the summer working on the clang static analyzer.

          +

            Eduard proposal:

              #

                Get clang static analyzer working with the Linux kernel

              #

                Add checker to LLVMLinux buildbot with statistics

              #

                Which checks are useful for the kernel, which checks
                need to be changed, which checks can be removed, which
                need to be added

          +

            Both Jan-Simon and Behan will be his GSoC mentors

      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

          +

            Now officially approved micro Conference

          +

            Approaching people to come speak and problem solve

      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

          +

            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

              #

                nexus7 target

              #

                rpi target

          +

            Fix Nexus 7 build

          +

            Add U-Boot target

      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
                build bot


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

*

-- 
Behan Webster
behanw at converseincode.com

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