[llvmlinux] LLVMLinux Meeting 2014-05-07

Behan Webster behanw at converseincode.com
Fri May 9 22:44:14 UTC 2014


*

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


This time the meeting was on Thursday, May 07 2014 on Google Plus 
Hangout at 15:00 UTC.


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

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

          +

            Fix VLAIS patches and submit upstream

          +

            Follow up on netfilter patch

          +

            fix v3.15 kernel breakage

          +

            buildbot work

          +

            Get ready for ELC/ABS

      o

        Jan-Simon

          +

            Follow-up with HPA on -no-387 cflags -> cc-option or other
            solution

          +

            mbcache compiler crash !!

          +

            intermediate bot for linux-next

          +

            -m16 vs code16gccflags (might be cc-option related)

      o

        Andrew Wells

          +

            read/research on static analyzers

          +

            look through what is already there (sparse, coccinelle)

          +

            modify timeline on proposal

          +

            annotation added for sparse, see if valid for clang

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

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

          +

            Pull request into v3.15 was accepted

          +

            Spoke at Embedded Linux Conference on LLVMLinux project

          +

            Spoke at Android Builders summit on compiling AOSP with clang

          +

            Worked on getting more LLVMLinux patches into for-next
            (arch/all, arm, and x86_64)

          +

            A few patch rewrites

          +

            Fixed beaglebone (white/black) target build

          +

            Worked on fixing breakage from new kernel merge window

          +

            Working on new buildbot

      o

        Jan-Simon

          +

            linux-next boots

          +

            New buildbot:

              #

                brainstorm

              #

                https://github.com/dl9pf/llvmlinux-buildbot/tree/resetup

              #

                we will have remote builders

              #

                main instance will just provide

                  *

                    git poller

                  *

                    llvm poller

                  *

                    buildsteps

                      o

                        llvm/clang:  configure + build + install
                                                          + record git IDs

                      o

                        targets: make, make test-kill (or new make test-bot)

                  *

                    4 reference builds (llvm, clang, vexpress, x86_64)

                  *

                    a clang build passing all of these tests will be
                    recorded (git IDs for the remote builders to reuse)

                  *

                    remote builder for x86_64-next with test in qemu

                  *

                    remote builder for beaglebone with boot test on HW

      o

        Vinicius Tinti

          +

            Add panda target for linaro

          +

            Add vexpress-linaro target for linaro

          +

            Integrating with LAVA

          +

            Creating a Vagrant/Puppet machine for buildbot

          +

            Nexus 7 does not build anymore.

      o

        Mark

          +

            Checking new targets

              #

                cubieboard

          +

            Added qemu 2.0

          +

            IFC board still not booting. Probably needs JTAG to resolve

  *

    (45 mins) General meeting discussions:

      o

        GSoC

          +

            Sadly Andrew Wells will not be our GSoC student this year.
            He was accepted into multiple organizations and we lost him
            during GSoC de-duplication

          +

            He still would like to work with static analysis checkers

      o

        Kernel patches

          +

            9 patches made it into mainline for v3.15

          +

            Another 2-3 patches were accepted through maintainer trees

          +

            2 more patches have been sent to fix merge window breakage

              #

                Turning off 80387 on x86

                  *

                    Wrapping -mno-80387 with cc-option

                  *

                    Use of FPU is explicitly disabled to make sure no
                    floating point instructions are ever issued

                  *

                    Currently gcc enforces that. Still investigating how
                    to do the similar thing with clang. Might have to
                    just turn off all FPUs manually.

              #

                __builtin_log2

                  *

                    mbcache.c uses log2 to calculate hash value

                  *

                    In clang it was generating a double, which was then
                    cast as a unsigned long

                  *

                    gcc on the otherhand was generating a long

                  *

                    Mark patched it to use the kernel ilog2() macro instead.

                  *

                    Using __builtin_log2l also might have solved the problem

          +

            All the above patches should end up in v3.15

          +

            Named Registers in Clang

              #

                Named register support has made it into LLVM, but Renato
                is having troubles convincing the clang folks to make
                changes to support it in the front end

              #

                So back to our original named register kernel patches

              #

                gcc supports many different kinds of allocatable
                registers using the same syntax

              #

                Global allocatable register are much more likely to be
                accept rather than local allocatable. Implement first
                global that will solve partially the usage on kernel

          +

            Integrated-as:

              #

                x86:

                  *

                    David Woodhouse is still working on enabling
                    integrated-as on x86_64sting more of the error
                    messages to Renato so he can see if th

                  *

                    -m16 needs debugging regarding cc-option

              #

                arm

                  *

                    Renato is working with Vinicius in order to get IA
                    working with ARM. Mostly poey can be fixed.

              #

                A number of macro expansion issues have been fixed

              #

                BUG macro is still broken

              #

                http://llvm.org/bugs/show_bug.cgi?id=19317

          +

            Example subject lines for patches:

              #

                Subject: [PATCH no-upstream] USB: LLVMLinux: Remove
                VLAIS from gadget driver

      o

        New buildbot

          +

            Behan and Jan Simon are working on building the new buildbot
            VM Ubuntu Server

              #

                Master builder will run all the VCS pollers

              #

                Master builder will build clang, llvm, vexpress, x86-tiny

              #

                Successful clang builds will be used as known good clang
                versions for the rest of the target builds

              #

                All other targets will be built on other (remote slaves)

              #

                This allows people to run local builds to allow local HW
                testing

              #

                Some build targets will be pushed to the LAVA test
                system at Linaro

          +

            The old buildbot is broken (distro/gcc/glibc is too old to
            compile clang)

          +

            Vinicius is working on getting builds integrated into LAVA
            testing at Linaro

      o

        Conferences

          +

            Behan spoke at Embedded Linux Conference on LLVMLinux project

              #

                http://sched.co/1oqUC2f

          +

            Behan spoke at Android Builders summit on compiling AOSP
            with clang

              #

                http://sched.co/1or07Oy

          +

            Behan has submitted talks to LinuxCon US (Chicago) and
            Linaro Connect US (SFO)

      o

        Dev boards

          +

            New Qualcomm DragonBoard IFC6410 (APQ8064 Quad-core A15 with
            GPU)

          +

            Mark, Behan and Jan-Simon now all have this board

          +

            The BeagleBone White and Black boards now have a working
            target (the BB kernel code is now in mainline) A few patches
            are required to support this build.

      o

        Build system updates

          +

            You can now build llvm/clang with your system clang (instead
            of gcc)

              #

                make CLANG_SELFHOST=1 clang

          +

            At Vinicius' request, Behan added the ability to add a
            target to allow kernel configs to be dynamically built so
            that Vinicius can support the Linaro kernel config which is
            built from "config fragments"

              #

                Tested and working.

  *

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

      o

        Behan

          +

            Buildbot rework

          +

            Named register patch work

          +

            Submit more patches to lkml so that I can send them to
            linux-next

      o

        Jan-Simon

          +

            buildbot rework

          +

            testing setup beaglebone black/white (buildslave)

          +

            x86-64-next buildslave testing with qemu/kvm

      o

        Vinícius Tinti

          +

            check integrated assembler

          +

            buildbot rework

          +

            lava integration

          +

            fix nexus7

          +

            probably n4

      o

        Mark

          +

            jtag for IFC

Next meeting in roughly 3 weeks (probably after Embedded Linux 
Conference). doodle poll to follow.

*

-- 
Behan Webster
behanw at converseincode.com

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