[llvmlinux] LLVMLinux Meeting minutes 2013-03-12

Behan Webster behanw at converseincode.com
Sat Mar 16 00:48:10 UTC 2013


*LLVMLinux Project: http://llvm.linuxfoundation.org/
<http://llvm.linuxfoundation.org/>
This week the meeting *wa*s on Tuesday, Mar 12 2013 on Google Plus 
Hangout at 9pm 
UTC<https://www.google.com/calendar/embed?src=su5vu85fj58ncfrgalmq4vbbf0%40group.calendar.google.com&ctz=GMT>

-------------------------------------------------------------------------------------------------------------------------
*Previous*meeting's top 2-3 work items:

  * (5 mins) Each meeting attendee listed the top 2 items to be worked
    on for the next 2 weeks
      o Behan:
          + At ABS and ELC next week
          + Write articles
          + Work on GalaxyS3 kernel


          + Getting SD working for QEMU
          + Patch review


      o Jan-Simon:
          + Teaching next 2 weeks
          + Will work on X86_64 and beaglebone
      o Tinti
          + Write documentation about how to build Android Nexus 7 and
            Galaxy S3 using a custom kernel.
          + Add cubieboard support (working on)
          + Buildroot for rpi (done)
          + khubd debug (working on)
          + Split checkpoint documentation
          + If I find time, make Nexus 7 display kernel boot messages on
            screen. After try on Galaxy S3.

-------------------------------------------------------------------------------------------------------------------------
Agenda this *meeting*:

  * (5 mins total) Everyone shared a quick summary of the progress
    they've made from the last 2 weeks
      o Behan:
          + Helped with clang port of Linaro Android
          + Worked on getting the latest clang/LLVM to not Segfault on
            vexpress build
          + Supported ryao in building with LLVMLinux patches for gentoo
          + General community building
          + Started linux.com article (topic: What is LLVM? Why bother
            with clang?)
      o Jan-Simon:
          + debug x86 bootup crash, patch from pipacs in build-system now.
          + x86_64 works, i586 follows
          + no time yet for bone
      o Tinti
          + Add buildroot support for rpi
              # Add targets for generating rootfs with modules
          + Add new target cubieboard support
              # Still not working due clang rejects a 'main' function
                with different parameters rather than (void) or (int
                argc, char **argv).
          + Debug khubd still no success.
          + Initial RPI 3.6.y support
      o Mark
          + Tested tip of Clang/LLVM - and continue testing a few times
            per week
          + Isolated crash and created self contained unit test
              # Forwarded internally to QuIC
          + Fixed the QEMU SD card issue for vexpress
              # Was missing ext4 support in the kernel config


(45 mins) General meeting discussions:

      o ABS Report
          + Linaro connections
              # Linaro team is investing on building Android with LLVM
                and publish their comparison with GCC.
      o ELC Report
          + Yocto connections
              # Yocto team is planning to add LLVM to meta-oe and
                possibly eventually core-oe
              # We can help them with llvm/clang which will make it
                easier for yocto to accept our patches
      o Distro Support
          + Yocto interested in building with llvm/clang
          + Gentoo (Ryao - gentoo clang maintainer) interested in
            building the kernel for Gentoo using ebuild.
      o New X86_64 patches
          + Pipacs sent a new patchset. Minor updates went in.
          + Patch for x86_64 crash went in (kudos pipacs)
          + pipacs used address sanitizer to fix some things

      o Merged globals/section mismatches update
          + Still needs more investigation
          + Investigation so far
            https://lftraining.dyndns.org/pad/p/llvm-section-mismatch
          + Clang seems to drop some attributes in the preprocessor
          + These dropped attributes mess up where init and exit code is
            linked which is causing the section mismatches
      o New arch all patches update
          + Thinkpad nested function patch written/reviewed/sent
            upstream (not yet accepted)
          + Spreadsheet to track patch review:
              # https://docs.google.com/spreadsheet/ccc?key=0Ao2VHhaw1DTqdERLUDBmVlpiY2pUNUlLa1k3ck1Zc1E#gid=0

      o VLAIS Update

          + Mark's VLAIS code still needs to be better integrated into
            our other VLAIS patches
          + Also still need better timing tests between VLAIS in gcc and
            new macros for clang to build a convincing reason to move
            away from VLAIS in the kernel
          + Behan will write an article about VLAIS in gcc/llvm in order
            to get better visibility.
          + We all agree to do an academic paper about VLAIS vs our
            alternative implementation and try to prove that they have
            the same performance in x86, x86_64 and ARM.
      o LLVM 3.3 update

          + Patches that must be sent upstream before LLVM 3.3
              # Existing x86 patches
              # segmentation difference issue (once fixed)
              # ARM segfault issue (once fixed)

      o Raspberry Pi Update
          + Intial 3.6.y is done (still need to build and test)
      o Nexus 7 Update
          + This is the proto target being used by Linaro
          + Add in Wikipedia that Clang was able to generate a working
            Android kernel?
              # Write a howto.
              # Add to wikipedia
      o Code Analyzer/IR
          + -emit-llvm support for IR analysis for the kernel code
              # -lindi (IRC)
              # Marcelo Souza
          + Static Analyzer (before April would be great).
      o LLVMLinux Evangelism
          + Perhaps a LWN article would be a good idea.
              # Works on rpi
              # Relatively few patches now
          + Behan has been asked to write an article for Linux.com on
            the topic of Linux and LLVM
          + Collab Summit coming up soon too
              # Behan will be giving a talk
          + Mark and Behan will lead the LLVM Micro-conference at Linux
            Plumbers Conference http://wiki.linuxplumbersconf.org/2013:llvm
              # Now looking for other people to give talks during the
                microconference
      o Review bug list (please update your bugs on the website before
        the meeting)
          + No review this week
      o Review todo/roadmap list  (please update your todos on the
        website before the meeting)
          + No review this week
      o Review the project Roadmap/Timeline to take us to the end of the
        year
          + https://docs.google.com/a/converseincode.com/spreadsheet/ccc?key=0AoeRmB6JBVt_dGYwSUNNNHd2SFFMWF9yMTRoa2VuZmc#gid=0

  * (5 mins) Each meeting attendee listed the top 2 items to be worked
    on for the next 2 weeks
      o Behan:
          + Work with yocto on getting llvm into meta-oe and kernel
            built with clang
          + Work on clang segfault for arm
          + linux.com article and VLAIS article
          + Patch review (both kernel and llvm)
          + Updates to build system to bundle patches for external
            builds (yocto and gentoo)
          + Talk with tinti on supporting multiple branches for rpi patches
      o Jan-Simon
          + Work on x86 to clean the patch queue, select patches for
            upstreaming
          + i586
          + llvm master
      o Tinti
          + Write documentation about how to build Android Nexus 7 and
            Galaxy S3 using a custom kernel.
          + Add in Wikipedia that Clang was able to generate a working
            Android kernel.
          + Work on VLAIS academic article
          + khubd
          + Raspberry Pi 3.6.y
          + Investigate clang 'main' function
      o Mark
          + Document script to fix segment symbol issues
          + Help to propagate my VLAIS fix to the VLAIS patches
          + Look at gadget driver re-write without VLAIS
          + Help to scope presentations for LPC mini-summit

*

Next meeting in 2 weeks

****

-- 
Behan Webster
behanw at converseincode.com

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