[llvmlinux] Minutes from LLVMLinux Meeting 2013.01.31

Behan Webster behanw at converseincode.com
Fri Feb 1 02:23:26 UTC 2013


*LLVMLinux Project: http://llvm.linuxfoundation.org/
<http://llvm.linuxfoundation.org/>
This week the meeting *wa*s on Tuesday, Jan 31 2013 on Google Plus 
Hangout at 5pm 
UTC<https://www.google.com/calendar/embed?src=su5vu85fj58ncfrgalmq4vbbf0%40group.calendar.google.com&ctz=GMT>

-------------------------------------------------------------------------------------------------------------------------
Last weeks top 2-3 work items:

      o Behan
          + Kbuild support
          + Work on talks for ELC and ABS
          + Better rootfs solution
          + Recheck whether Checker is still broken
          + Upstream patches
      o Jan-Simon
          + x86 builder
          + bug triage and marking necessary/cosmetic
          + FOSDEM talk
          + make test on x86
          + help tinti with rpi
      o Mark


          + Load Android image on DB 8060A
          + Compile kernel with clang and reload image with Clang kernel
          + Get Pragmatix build running, re-build pragmatix kernel with
            Clang
          + Check on upstream status of 64bit patches from QuIC
          + Document the use of his scripts to generate patches for
            segment linkage differences
          + Re-check CONFIG_STACK_PROTECTOR
      o Tinti
          + [Pending] Provide "checkpoint" for rpi
              # [Pending] Document how to generate the root filesystem
                and sdcard
              # [OK] Document how to proceed with "checkpoint"
          + [OK] Provide binaries for Jan-Simon
          + [Pending] Add support for kernel 3.6
          + [Working] Investigate USB issue
          + [OK] Merge branch back to master
          + [OK] Test with Android (not working)

-------------------------------------------------------------------------------------------------------------------------
**Minutes**for this week:

  * (5 mins total) Everyone shared a quick summary of the progress
    they've made from the last 2 weeks
      o Behan
          + Kbuild support
          + Worked on compiling Android with LLVM
          + Worked on buildroot for vexpress
          + Confirmed that checker was still not working
          + Reviewed arch/all patches with JSM
      o Jan Simon
          + Assisted Vicinius with Rpi
          + Worked on X86_64 patches (x86_64 is broken)
          + Talked to pipacs about x86_64 boot problems
          + Reviewed arch/all patches with Behan
      o Randy


          + Tried to build almost every day - no luck.
          + Skimmed the docs for info on how to get a sane build.
          + llvmlinux used to have a stable baseline, what happened?
          + I have less than a few hours per week.
      o Tinti
          + khubd is causing problems for USB on rpi
          + Worked with Jan-Simon on rpi
          + Merged checkpoint code
          + Encouraging people from rpi community to try it out


      o Mark


          + Worked on MSM target


(45 mins) General meeting discussions:

      o Build problems
          + Some instability with the build for Randy. Will work on it
            off line
      o New clang kbuild support
          + Can build without make-kernel.sh now
          + Works for all targets
          + Doesn't add warnings to gcc build
          + Updates to kbuild-clang.patch and kbuild-clang-arm.patch
          + More investigation into -isystem issues with android gcc
      o Buildroot rootfs generation (not small initramfs)
          + Generic buildroot support now available
          + SD card support may be broken currently with QEMU


      o Merged globals/section mismatches update
          + Still seeing a lot of these issues in all target builds
          + Still needs more investigation
          + Investigation so far
            https://lftraining.dyndns.org/pad/p/llvm-section-mismatch
      o New arch all patches update
          + Patch review
          + Can we remove some of the patches
          + Spreadsheet to track patch review:
              # https://docs.google.com/spreadsheet/ccc?key=0Ao2VHhaw1DTqdERLUDBmVlpiY2pUNUlLa1k3ck1Zc1E#gid=0
      o Checkpoint feature
          + Tinti had feedback from users that a mechanism to build a
            stable rpi build would be useful
          + Checkpoints are a wrapper around settings feature.
          + Enforces LLVMLinux git version listed in config/checkpoint file
          + Perhaps checkpoint documentation should be moved from
            settings_file.txt to it's own file
          + More documentation needs to be added to
            get_and_build_the_code.txt


      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
          + Vinti suggested an article about VLAIS in gcc/llvm in order
            to get better visibility
      o LLVM 3.3 update


          + No update this meeting


      o Raspberry-Pi Update
          + khubd is causing problems for USB on rpi
          + Still encouraging people from rpi community to try it out
      o Compiling Android with LLVM
          + This work is being done for Behan's talk for ABS
          + Mark will work on the MSM kernel for Android
          + Mark will add an S3 target to the LLVMLinux project
          + Behan will concentrate on Android user
      o LLVMLinux Evangelism
          + JSM is talking at FOSDEM (next week!)
              # The Linux Kernel with Dragon Wings
                <https://fosdem.org/2013/schedule/event/the_llvmlinux_project/>
              # Sylvestre Ledru also talking on "Make Debian compiler
                agnostic - Building Debian with LLVM/Clang"
                  * https://fosdem.org/2013/schedule/event/debian_clang/
          + Behan is talking at ABS (Feb 18-19) and ELC (Feb 20-22)
              # LLVMLinux: Compiling Android with LLVM
                <http://androidbuilderssummit2013.sched.org/event/70c55b4484d89429b4dbb28c28947d4c?iframe=no&w=900&sidebar=yes&bg=no#.UQBOoV1QAjI>for
                ABS
              # LLVMLinux: Compiling the Linux Kernel with LLVM
                <http://embeddedlinuxconference2013.sched.org/event/a608109d374ac283e395f6028e5d868c?iframe=yes&w=900&sidebar=yes&bg=no#?iframe=yes&w=900&sidebar=yes&bg=no>for
                ELC
          + 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
          + Mark and Behan we asked to 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
          + Collab Summit coming up soon too
              # Conference organizers have also approached us for talks
                for this conference as well
      o Review bug list (please update your bugs on the website before
        the meeting)
          + CONFIG_CC_STACKPROTECTOR is working now
      o Review todo/roadmap list  (please update your todos on the
        website before the meeting)
          + Next patch for arm 64-bit type handling has made it upstream
            to LLVM, though still more to go
          + Kbuild supported completed
      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
      o


  * (5 mins) Each meeting attendee listed the top 2 items to be worked
    on for the next 2 weeks
      o Jan-Simon:
          + x86 boot - follow up with pipacs
          + FOSDEM talk
              # Talk
              # Debian/Clang talk
              # Write email about FOSDEM
          + bug triage
      o Mark:
          + Get status of upstream 64 bit ARM type handling
          + Set up target for kernel for Samsung Galaxy S3
          + Document tool to update the missing segment references
          + Help Behan with VLAIS patches
          + Follow up with David Kipping on LLVM talk for Collaboration
            Summit
          + Help debug SD image loading in QEMU for vexpress (test3)
      o Tinti:
          + Work on khub for rpi
          + buildroot support for rpi
      o Behan:


          + Compiling Android with LLVM
          + Work on ABS and ELC talks
          + Document buildroot
          + VLAIS work
          + Getting SD working for QEMU
          + linux.com article
          + Patch review



*Chat:*


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

Randy MacLeod

12:48 PM

is there an open ICC/linux-kernel project? Share pain, patches?

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

Jan-Simon Möller

1:07 PM

https://lftraining.dyndns.org/pad/p/llvm-section-mismatch
[18:43:41] <jcranmer> Criswell: no, dl9pf is having some issues with
_attribute_((section), I think
[18:43:42] <dl9pf> https://88.198.106.157/irmod.i.tar.bz2 again
[18:43:55] <dl9pf> i removed the hardcoding from the macro.
[18:44:19] <dl9pf> static inline _attribute_((no_instrument_function))
initcall_t _inittest(void) { return irda_init; } int init_module(void)
__attribute_((alias("irda_init")));;
[18:44:23] <dl9pf> now it is missing
[18:44:30] <dl9pf> on gcc is it still there ...
[18:44:59] <Criswell> Okay. It sounded like you guys were trying to 
figure out
what the magic section stuff is supposed to do. I'm somewhat familiar with
the Linux magic sections, but that alias attribute must be something 
that is
new.
[18:45:33] <jcranmer> the gcc is outputting _attribute_((section)) still in
the preprocessed output
[18:45:45] <jcranmer> which implies that some preprocessor check is failing
that causes different output
[18:45:51] <dl9pf> jcranmer: exactly
[18:46:17] <dl9pf> reproducable - an that everywhere when compiling the 
kernel
[18:46:29] <dl9pf> we get a lot of section mismatches if we turn that 
check on
[18:46:52] <jcranmer> which means you need to work out what the 
preprocessor
is doing to figure out why the macros are being differently defined
[18:47:36] <dl9pf> good - hints where to start to look at ?
[18:48:35] <jcranmer> I'm afraid I don't
*

-- 
Behan Webster
behanw at converseincode.com

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