Toolchain WG - 2010-08-24 meeting minutes

Michael Hope michael.hope at
Tue Aug 24 03:46:25 BST 2010

Please find the activity reports and minutes for Monday's meeting
below.  The minutes are also available at:

Minutes from the Wednesday and Friday standup calls are at:

-- Michael


  • Name             Email                    IRC Nick
    Andrew Stubbs    andrew.stubbs at ams
    Chung-Lin Tang   cltang at  cltang
    Matthias Klose   doko at       doko
    Michael Hope     michael.hope at  michaelh
    Peter Maydell    peter.maydell at pm215
    Richard Earnshaw richard.earnshaw at rearnshaw
    Yao Qi           yao.qi at        yao


  • Open tickets
      □ 616141 Backport the sync_* primitive fixes
      □ 590696 fix wrong use of objdump during cross build
      □ 600277 Backport ARM Cortex A9 scheduling changes
      □ 605059 Merge 4.4.5
  • Upcoming release
      □ GCC 4.4
      □ GCC 4.5
      □ GDB
      □ Strings
  • 4.6 backport approach
  • Creating blueprints
  • Connecting with other groups

    Blueprint                          Assignee
    Initial delivery of Linaro GCC 4.4 ams
    Cross Compiler Packages            hrw

Action Items from this Meeting

  • ACTION: Chung-Lin to move the list of other backports out of the CSL wiki
    and into Linaro
  • ACTION: Michael to re-check with TSC that we can assign copyright but keep
    ability to relicense
  • ACTION: Yao to continue on GDB for a week then switch to investigation
  • ACTION: Peter to check into the state and progress of valgrind for the
    meeting on the 30th.

Action Items from Previous Meeting



  • Went through the open tickets in the agenda
  • Andrew will backport the SMP changes, including the sync primitives
  • Andrew will backport the A9 changes
      □ Most of the changes should come through easily
      □ There is a write after write hazard
      □ Currently uses the new cost infrastructure
      □ Backport the cost infrastructure if it will be used further in the

4.6 branch:

  • Andrew suggested starting a 4.6 branch after the start of stage 3
      □ Start landing patches early
      □ When FSF 4.6.0 comes out, we will have a corresponding Linaro 4.6.0
  • ACTION: Chung-Lin to move the list of other backports out of the CSL wiki
    and into Linaro

String routines:

  • Richard asked about the response
  • Michael had replies from Roland McGrath (
    libc-alpha/2010-08/msg00029.html) but not the wider gcc-sc
  • All other architectures are LGPL and FSF assigned
  • The current approach is to assign a particular version to glibc
  • Could cause a small maintenance problem in the future
  • Richard isn't sure that we can assign copyright of a particular version
  • ACTION: Michael to re-check with TSC that we can assign copyright but keep
    ability to relicense

4.6 backports:

  • Talked about the approach for backporting 4.6 features
  • Won't backport every single change as then Linaro 4.5 becomes FSF 4.6
  • Backport correctness fixes as the problem is found
  • Backport performance changes as they occur
  • Discussed how upstream could be tracked
      □ Notification of any CSL or ARM authered changes will come from them
      □ All changes are supposed to go through gcc-patches
      □ Andrew notes that gcc-cvs provides a filtered view of what actually
      □ At least monitor these lists and search for ARM|Thumb|NEON|XSCALE|

Michael noted that IBM are interested in the ARM compiler and plan to get
involved soon.

Michael has asked again for A9 hardware. No news yet.


  • Would like to spend some time soon running invetigrations to spit out some
  • ACTION: Yao to continue on GDB for a week then switch to investigation
  • Andrew noted that there is one more person to come from CSL
  • Will ask that person to do investigation
  • Richard is keen to see the blueprints to check against what ARM is doing
      □ Michael asked for information about their planning process so that we
        can line things up


  • Peter noted that the valgrind changes have been committed upstream
  • ACTION: Peter to check into the state and progress of valgrind for the
    meeting on the 30th.

Next meeting is a stand-up meeting on 2010-08-25 on the public code.

--- Andrew Stubbs
== GCC 4.5 ==

 * Continued pushing 4.5 patches to Linaro. I have now caught up with
current development I think.

 * Lots of discussion on the patch tracker. You'd think it was more
important than the compiler .... :(

== Upstream ==

 * Did before and after tests of the Coretex-A5 scheduler against
upstream HEAD. All seemed well (or at least, no worse) so I've posted
the patch upstream. No word back yet ....

--- Chung-Lin Tang
 == Hard-float ==
* Testing EEMBC softfp vs. hard-float calling convention performance numbers.

* The only conclusive result was that OAmark is 2%-3% faster,
presumably due to vector graphics-like code in that suite. May look
into other code (was suggested Cairo) to see if any gain in changing
to hard-float.

* Withdraw earlier comment on small improvements on Automark (was not
apparent after more experiment runs).

* Currently working to produce report files.

== Linaro GCC ==
* Looking at getting into GCC backport work this week.

--- Yao Qi

== Linaro GDB ==

 * LP:615997 gdb.dwarf2/dw2-ref-missing-frame.exp failure
 Patch is committed to gdb mainline.

 * LP:615999 gdb.gdb/selftest.exp failure
 Patch is committed to gdb mainline.

 * LP:615995 gdb.base/watch-vfork.exp : Watchpoint triggers after
vfork (sw) (timeout)
 With Pedro's help, got to know the failure of this case on arm and
x86 are different.  Created a patch as Ulrich suggested, and it works
on 2.6.32, while fails in a different way on 2.6.35.  Failure is
caused by debuggee process is killed by a SIGTRAP.  Still no clue why
that can happen.

== Linaro GCC  ==

 * My patch to PR45094 is approved, and checked in to mainline.

== This Week ==

 * Fix LP:615995 and other linaro gdb bugs.

--- Ulrich Weigand

== GCC ==

 * Collected and wrote up suggestions for future GCC work

== GDB ==

 * Opened Launchpad bugs for known GDB problems and testsuite failures
 * Investigated bug #620595 (gdb.threads/threxit-hop-specific.exp failure)
 * Fixed bug #615998 (gdb.gdb/observer.exp failures) in mainline and 7.2
 * Worked on upstream fix for #620595 (gdb.threads/threxit-hop-specific.exp
 * Analyzed bug #620611 (Unable to backtrace out of vector page 0xffff0000)

== Infrastructure ==

 * Continued working with our order&control team to acquire IGEPv2 boards

--- Peter Maydell

Red:   None
Amber: ARM legal OK for qemu contributions still pending
Green: we have approval for laptops for linaro secondees

                              | Planned    | Estimate   |  Actual  |
finish virtio-system           | 2010-08-27 | 2010-08-27 |          |


 - got my versatile kernel/qemu running with virtio disk and network
  versus non-virtio
 - ran some basic benchmarking (bonnie++ for disk, tbench for net).
  Disk is faster with virtio, but strangely networking is not!
 - tried an upstream qemu too -- net virtio still slower
 - built a realview kernel in preparation for testing Arnd's
  PCI patches on hardware

 - some research into which ARM dev boards support PCI in
  hardware, kernel and qemu, to try to find a good choice for
  basing a qemu-focused kernel on

 - started compiling list of qemu branches for possible consolidation

Issues: the intersection of (recent ARM hardware) (PCI support)
and (supported in qemu) looks suspiciously like the empty set.

 - borrow some versatile or realview hardware and test Arnd
  Bergmann's PCI patches
 - make a start on writing up the config/benchmark results
 - flesh out this blueprint
 - try to build an ARM valgrind from upstream's thumb branch

Friday 5 November and 20 other days in this calendar year

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