- linaro-toolchain - lists.linaro.org

by Revital Eres

Hello, - Continued analysing DENbench benchmarks. - Discussed the SMS patched with Ayal Zaks (SMS maintainer). - Booked the flights for Budapest summit. Thanks, Revital

14 years, 5 months

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[ACTIVITY] April 27-28

by Ira Rosen

Hi, gcc-linaro/4.6 - if-conversion improvement (needed to vectorize Telecom/viterbi) - merged - auto-detection of vector size - proposed for merging GCC FSF - fixed PR 48765 on trunk - completed testig of vzip fix (PR 48252) on gcc 4.5 and gcc 4.6 Ira

14 years, 5 months

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[ACTIVITY] weekly status

by Ken Werner

Hi, libunwind: * the initial support for resuming at a certain stack frame went upsream * learned about the various signal frame layouts on ARM * RT frames, non-RT frames for present and pre 2.6.18 kernels * implemented support for RT signal frame detection on ARM * started to implement support for unw_resume if signal frames are involved * attended a class on Friday Note: Monday was a public holiday. Regards Ken

14 years, 5 months

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[ACTIVITY] Apr 26 - Apr 29

by Ulrich Weigand

== GDB == * Committed series of patches to fix bug #615978 (Failure to software single-step into signal handler) to mainline and Linaro GDB. * Drafted blueprint linaro-toolchain-o-cross-debug == GCC == * Split bug #771900 (Linaro GCC 4.5 switch optimization breaks profiled bootstrap) off bug #759409 (Profiled bootstrap fails in GCC 4.5). Tracked down root cause of bug #759409 / PR middle-end/43085, and posted fix to gcc-patches. Mit freundlichen Gruessen / Best Regards Ulrich Weigand -- Dr. Ulrich Weigand | Phone: +49-7031/16-3727 STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E. IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martin Jetter | Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen | Registergericht: Amtsgericht Stuttgart, HRB 243294

14 years, 5 months

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Toolchain summit blueprints

by Michael Hope

Hi there. The toolchain session blueprints for the summit are now up on Launchpad: https://blueprints.launchpad.net/linaro-toolchain?searchtext=toolchain-o You can check out the schedule here: http://summit.ubuntu.com/uds-o/track/linaro-toolchain/ although it's really only for show at the moment. Expect things to jump around as the constraints kick in. Please go through these blueprints and subscribe yourself to them. You can check your list of blueprints at: https://blueprints.launchpad.net/people/+me?searchtext=toolchain-o -- Michael

14 years, 5 months

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"BFD_ASSERT (out_attr[Tag_ABI_HardFP_use].i == 0) " assert

by Barry Song

Hi All, I found Jie has committed a patch "http://sourceware.org/ml/binutils/2010-05/msg00083.html". I am using the newest binary utils(2.21) and encounted the following ASSERT in arm_elf32.c: + if (out_attr[i].i == 0) + { + BFD_ASSERT (out_attr[Tag_ABI_HardFP_use].i == 0); My compiling options are as below, ASM_FLAGS := \ -gdwarf-2 \ -mfpu=vfp \ -mfloat-abi=softfp \ -mthumb-interwork C_FLAGS := \ $(ASM_FLAGS) \ -O3 -Wno-all \ -fno-optimize-sibling-calls \ -mlong-calls \ -ffunction-sections \ CPP_FLAGS := \ -fno-rtti \ -fno-exceptions \ LINK_FLAGS := \ --gc-sections -nostdlib \ -L ../stdlib \ -Wl,--as-needed \ -Wl,-no-enum-size-warning \ --cref \ ARFLAGS := \ rcs Can anyone give me any tip about why the assert is triggered? I have reported a bug here: http://sourceware.org/bugzilla/show_bug.cgi?id=12700 But not sure whether it is a bug. -barry

14 years, 5 months

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__aeabi_uldivmod undefined for sound/soc/codecs/snd-soc-wm8974.ko, snd-soc-wm8940.ko and snd-soc-wm8510.ko

by Barry Song

Hi All, I am using 2011.3 4.5 linaro GCC(armv7-a vfpv3d16) to compile kernel and modules. I select to compile all codecs as modules: "config SND_SOC_ALL_CODECS tristate "Build all ASoC CODEC drivers" " as M and I2C/SPI too. Then in the kernel dir, run "make" to get both vmlinux and modules, I found snd-soc-wm8974.ko, snd-soc-wm8940.ko and snd-soc-wm8510.ko will fail due to "__aeabi_uldivmod undefined". If i comment do_div() in these codec drivers, this issue will disappear. But it is strange there are many codecs which use do_div() too, for example: sound/soc/codecs/max98088.c sound/soc/codecs/max9850.c sound/soc/codecs/wm8350.c sound/soc/codecs/wm8400.c sound/soc/codecs/wm8510.c sound/soc/codecs/wm8580.c sound/soc/codecs/wm8753.c sound/soc/codecs/wm8804.c sound/soc/codecs/wm8900.c sound/soc/codecs/wm8904.c sound/soc/codecs/wm8940.c sound/soc/codecs/wm8955.c sound/soc/codecs/wm8960.c sound/soc/codecs/wm8974.c sound/soc/codecs/wm8978.c sound/soc/codecs/wm8985.c sound/soc/codecs/wm8990.c sound/soc/codecs/wm8991.c sound/soc/codecs/wm8993.c sound/soc/codecs/wm8994.c sound/soc/codecs/wm8995.c sound/soc/codecs/wm9081.c but others can pass the compiling except those 3 modules. Is it due to a wrong optimization by gcc? Other information: 1. old tool-chains we are using can pass the compiling of the 3 modules. 2. If i built all codecs into kernel image, these 3 drivers don't report error while compiling. Thanks Barry

14 years, 5 months

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Re: [alsa-devel] [PATCH] ASoC: prevent compilers from optimising pll calculation into __aeabi__uldivmod

by Barry Song

2011/4/27 Mark Brown <broonie(a)opensource.wolfsonmicro.com> > > On Wed, Apr 27, 2011 at 04:50:12PM +0800, Barry Song wrote: > > > Marking pll_factors() as noinline or putting asm("" : "+r"(source)); before the > > call to do_div() works around the problem. > > If we do have to do something in the callers rather than in do_div() the > annotation seems substantially more taseful than inserting a random asm > into the code. I agree. for this patch which will not be applied, people can just get information about how to workaround the gcc issue while they have the same problem. google can find there are other people who failed to compile wm8974 module too. eg. http://irclogs.ubuntu.com/2010/03/30/%23ubuntu-arm.txt Andrew Stubbs, Michael Hope in Linaro's toolchain team are working hard on this gcc issue. there have been many update today: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48783

14 years, 5 months

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-O2 cause optimization issues while va parameters functions

by Barry Song

Hi All, As i have frequently said, we are using 2011.3 4.5 linaro gcc. For the following codes, if we compile it by -O2, it will crash with "segment fault", if we just comment " if(unifi_debug >= level) {", all will be ok. If we don't compile it by -O2, all will be ok too. #include <stdlib.h> #include <stdio.h> #include <stdarg.h> #define DEBUG_BUFFER_SIZE 80 int unifi_debug = 5; void unifi_trace(void* ospriv, int level, const char *fmt, ...) { static char s[DEBUG_BUFFER_SIZE]; va_list args; unsigned int len; if(unifi_debug >= level) { va_start(args, fmt); len = vsnprintf(&(s)[0], (DEBUG_BUFFER_SIZE), fmt, args); va_end(args); if (len >= DEBUG_BUFFER_SIZE) { (s)[DEBUG_BUFFER_SIZE - 2] = '\n'; (s)[DEBUG_BUFFER_SIZE - 1] = 0; } printf("%s", s); } } int main(void) { char *prog = "/usr/sbin/unififw"; unifi_trace(NULL, 1, "start %s\n", prog); return 0; } Thanks Barry

14 years, 5 months

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Sessions for the summit

by Michael Hope

Hi there. A first-pass list of summit sessions is up at: https://wiki.linaro.org/MichaelHope/Sandbox/1111Blueprints The next step is to investigate these areas and come up with a basic plan that can be discussed during the summit. I've put your names against the sessions as follows: Andrew: Broad tuning Dave: String routines everywhere Dave: QEMU topic #2 Doug: STM support Ira: Vectoriser and NEON performance Ken: 64 bit sync primitives Ken: Good backtracing Ken: End-developer tools bluesky Michael: Publish benchmarking of the toolchain Michael: Binary builds Michael: Deeper validation Peter: QEMU bluesky Ramana: Thumb-2 performance brainstorm Ramana: GCC backend rework Ulrich: GDB as a cross-debugger Ira and Dave, I know you won't be at the summit but we'll see about being able to call in. Could you all please have a read of the outline, investigate these topics, and draft up a blueprint-style list of work items to achieve it? Record any notes in the sandbox page[5] or in a child page if needed. Larger topics may warrant a specification[1]. I'd like these done by the end of next week. I'd expect to spend up to a day on the topics you already understand and more on broad topics. For reference, the see the draft TRs[2] and spreadsheet [3]. I've added some GDB topics to the spreadsheet that still need to go onto the wiki page. The outlines should touch each of these TRs in some way so let me know if I've missed anything. There's more good information on the process and style at: https://wiki.linaro.org/Process/Blueprints https://wiki.linaro.org/Process/WorkItemsHowto https://wiki.linaro.org/Resources/FAQ Questions? Need more detail? Let me know. -- Michael [1] https://wiki.linaro.org/Process/SpecTemplate [2] https://wiki.linaro.org/Cycles/1111/TechnicalTopics/Toolchain [3] https://spreadsheets.google.com/ccc?key=0Ap7fWLePADFVdHkxYy1INTZmMEd4bkwxSG… [4] there is no 4... [5] https://wiki.linaro.org/MichaelHope/Sandbox/1111Blueprints

14 years, 5 months

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[ACTIVITY] 18th - 21st April

by Andrew Stubbs

Merged & tested the outstanding merge requests into Linaro GCC. Spin the Linaro GCC 4.5 and 4.6 releases. Uploaded the tarballs to Michael. Submitted a patch upstream that removed some redundant code that had confused me a introduced a bug into my Thumb2 constants patch. http://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg03756.html This patch is now approved and committed upstream. I'll commit it internally when the rest of my ARM/Thumb constant handling changes are upstream. Worked on addressing RichardE's concerns with my Thumb2 constants patch. Tried to split it into smaller chunks, and rename the constraints. Posted the patches upstream: 1. a small patch upstream to clean up MOWV support. http://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg03768.html (Now approved and committed.) 2. ADDW and SUBW support. http://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg03783.html 3. Replicated constants for constant splitting. http://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg03883.html Committed upstream Dan's Vector shift test cases patch that was approved last week. Pushed the same patch to Linaro GCC 4.6. ---- Upstream patched requiring review: * NEON scheduling patch http://gcc.gnu.org/ml/gcc-patches/2011-02/msg01431.html * ARM EABI half-precision functions (reposted 2011-04-14) http://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg03210.html * ARM Thumb2 addw/subw support. http://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg03783.html * ARM Thumb2 Replicated constants http://www.mail-archive.com/gcc-patches@gcc.gnu.org/msg03883.html

14 years, 5 months

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Performance meeting agenda for today.

by Ramana Radhakrishnan

Hi, Agenda for today's performance call . Sorry about the last minute posting and I'll put this in the wiki soon enough. 1. Sync-up on what's been happening around the group: a. Coremark regressions. b. Thumb2 constants patch. c. divmodsi4 and vfp register moves. d. DENBench investigations. 2. Planning for the summit and turning some of the ideas into blueprints. 3. AOB. cheers Ramana

14 years, 5 months

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[ACTIVITY] Apr.18 -- Apr.24

by Chung-Lin Tang

== Last week == * PR48250, rehaul arm_legitimize_reload_address(). Richard Sandiford caught a bug of mine where I overlooked the valid index range of NEON quad-word load/stores. Quickly whipped up a fix, soon approved and committed upstream. * LP #744754, ICE in NEON struct-mode auto-inc-dec MEMs. Pushed upstream patch for a merge to Linaro 4.5. * PR46888, bit-field insert optimization patch. Resumed investigating, mailed Andrew Pinski for more information on that REG_EQUAL note issue he mentioned on gcc-patches; can't quite reproduce it myself. * CoreMark ARMv6/v7 regressions: posted a patch set to gcc-patches. Still waiting review. * Reported to Bernd and AndrewS on an issue (LP #748138) which seems to be related to the shrink-wrap patch. This ICE does not seem to be avoided by doing -fno-shrink-wrap. * A few tasks related to Linaro-Budapest event travel. == This week == * Do the merge of the new combine patches to Linaro, and test. * LP #689887 is still in progress. * Hope to experiment with a few more optimization ideas.

14 years, 5 months

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NEON intrinsics vs. assembly code

by Richard Sandiford

Michael mentioned that some users reported seeing better preformance from RVCT using arm_neon.h then they did when coding directly in assembler. He suggested we try the same thing for GCC. Here's an experiment using the example that Jim Huang posted to the dev list recently: https://wiki.linaro.org/RichardSandiford/Sandbox/IntrinsicsPerformance The summary is that the C version needs to borrow a trick from the assembly code in order to be competitive. If it does that, though, the C code can be faster. I think this is mostly down to scheduling, although I haven't checked in detail yet. Richard

14 years, 5 months

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[ACTIVITY] 2011-04-21

by David Gilbert

== String and Memory routines == * Profiled denbench with perf and produced a set of stats to show which programs spent how much time in libc and how much time was spent in each routine. While some of the benchmarks are good (like aes) and spend almost no time in libc some of the others (MPEG codecs especially) seem to spend significant times in libc. * Ran all of denbench through latrace to generate sets of library calls; post processed them to extract the section between the clock() calls (and hence in the timed portion) and analysed the hot library calls. I've looked at some of the output but not all of it yet; I get output like: Memcpy stats (dst align/src align/length/number of occurrences/total size copied) memcpy: 0,0,1 , 1588520, 1588520 memcpy: 16,28,4096 , 1, 4096 memcpy: 4,20,16384 , 855, 14008320 This shows that for a bunch of tests they do an inordinate number of 1 byte memcpy's, and a few hundred larger memcpy's with an address %32 which is 4 (and destination %32 is 20) - so not aligned but at least equally misaligned. * Started writing up a report on some of the stats * Also started to try and extract the same stuff from SPEC2k6 == QEMU == * Tested Peter's QEmu release earlier in the week (On Lucid so didn't hit his natty bug) * Wrote up a couple of specs (one for TrustZone and the other for Device Tree integration)

14 years, 5 months

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[ACTIVITY] Weekly status

by Revital Eres

Hello, Submitted the following patches to GCC trunk: [1] Avoid unfreed memory when SMS fails (committed to trunk GCC) - http://gcc.gnu.org/ml/gcc-patches/2011-04/msg01204.html [2] Free sccs field (committed to trunk GCC)- http://gcc.gnu.org/ml/gcc-patches/2011-04/msg01205.html [3] New flag to apply SMS when SC equals 1 (committed to trunk GCC) - http://gcc.gnu.org/ml/gcc-patches/2011-04/msg01293.html [4] Avoid considering debug_insn when calculating SCCs - http://gcc.gnu.org/ml/gcc-patches/2011-04/msg01294.html [5] Support instructions with REG_INC_NOTE - http://gcc.gnu.org/ml/gcc-patches/2011-04/msg01309.html Returned looking into DENbench's benchmarks. Thanks, Revital

14 years, 5 months

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[ACTIVITY] Apr 18 - Apr 21

by Ulrich Weigand

== GDB == * Created Linaro GDB 7.2-2011.04-0 release. * Committed patch to fix accessing "fpscr" register to Linaro GDB. * Failure to disable address space randomization (bug #616001) has been fixed in the kernel; closed the Linaro GDB bug. == GCC == * Ongoing analysis of bug #759409 (Profiled bootstrap fails). Identified two independent problems, one related to a new CodeSourcery feature, and one a mis-optimization of final-stage cc1plus which is also present in FSF GCC 4.5 (PR 43085). Ongoing investigation to track down the root cause of the latter problem. == Schedule == * Public holidays 04/22 - 04/25. Mit freundlichen Gruessen / Best Regards Ulrich Weigand -- Dr. Ulrich Weigand | Phone: +49-7031/16-3727 STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E. IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martin Jetter | Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen | Registergericht: Amtsgericht Stuttgart, HRB 243294

14 years, 5 months

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[ACTIVITY] report week 16

by Peter Maydell

RAG: Red: Amber: Green: another monthly qemu-linaro release out on schedule Current Milestones: | Planned | Estimate | Actual | qemu-linaro 2011-04 | 2011-04-21 | 2011-04-21 | 2011-04-21 | Historical Milestones: finish qemu-cont-integration | 2011-01-25 | 2011-01-25 | handed off | first qemu-linaro release | 2011-02-08 | 2011-02-08 | 2011-02-08 | qemu-linaro 2011-03 | 2011-03-08 | 2011-03-08 | 2011-03-08 | == maintain-beagle-models == * qemu-linaro 2011.04 tested and released * had to do another last minute -1 respin to fix a problem caught by ubuntu package builds; we need to come up with a process that lets us do test package builds prior to release so we can fix this sort of issue in a less last-minute fashion == merge-correctness-fixes == * sent patch: fix semihosting SYS_HEAPINFO (seems to have issues though) * sent patch: UNDEFs in Neon load/store space * sent patches: fix build issues on sparc * sent patch: bump the initrd load address to work with bigger kernels * sent patch: set Invalid flag for float-to-int conversion of NaN * sent patch: move vld/vst multiple to helper functions * reviewed patches from Aurelien doing some general softfloat cleanup * sent out a version of my performance counters patch which just does a basic dummy implementation without the cycle counter (since the cycle counter bits were going off down a blind alley rather and this part is the last thing needed to be able to boot Linaro vexpress images on stock upstream QEMU) == other == * trying to nail down proposed QEMU work for next cycle; work-in-progress: https://wiki.linaro.org/PeterMaydell/Qemu1111 * meetings: toolchain, standup Current qemu patch status is tracked here: https://wiki.linaro.org/PeterMaydell/QemuPatchStatus Absences: Holiday: 22 Apr - 2 May 9-13 May: UDS, Budapest (maybe) 15-16 August: QEMU/KVM strand at LinuxCon NA, Vancouver [LinuxCon proper follows on 17-19th]

14 years, 5 months

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[ACTIVITY] weekly status

by Ken Werner

Hi, libunwind: * added initial support for resuming at a certain stack frame * posted unw_resume support plus some some testsuite fixes on the ml * there are still some issues left if signal handlers/frames are involved Note: Friday is a public holiday. Regards Ken

14 years, 5 months

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[ACTIVITY] Weekly status

by Richard Sandiford

== This week == * Iterated with upstream on some of the vectorisation patches. I think only half a patch (the ARM implementation of array_mode_supported_p) is still pending review; everything else has been approved. * Backported the vldN and vstN intrinsics to Linaro 4.5. * Finished off the microbenchmarks for libav. * One of the problems in the original libav output was that the vectoriser didn't realise that a group of N accesses really did form a group. It instead generated N separate interleave operations and took 1 vector from each. Submitted a fix for that, which is now committed upstream. Updated the libav wiki page with the new, improved output. (This actually allowed more libav loops to be vectorised, as well as improving the output from some of the existing ones. I haven't looked at the new ones. I expect this comes from interleaved stores.) * Wrote an arm_neon.h version of Android's scanline_t32cb16_neon and compared it with the original. * Started (and only started) seeing how the vectorisation stuff affects DENbench. * Backported the dwarf2out OOM fix to Linaro 4.6. == Next week == * Do something useful on DENbench. * If all goes well, commit the vectorisation work upstream and backport it to Linaro 4.5 and 4.6. ...but it's only a three day week. Richard

14 years, 5 months

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Linaro QEMU 2011.04-1 released

by Peter Maydell

The Linaro Toolchain Working Group is pleased to announce the release of Linaro QEMU 2011.04-1. Linaro QEMU 2011.04-1 is the third release of qemu-linaro. Based off upstream (trunk) qemu, it includes a number of ARM-focused bug fixes and enhancements. Interesting changes include: - Compiling for an ARM host in Thumb mode now works - As usual, various minor correctness fixes and other upstream changes Known issues: - The beagle and beaglexm models do not support USB, so there is no keyboard, mouse or networking (#708703) The only change over the shortlived 2011.04-0 is to fix a compilation failure with gcc 4.5. The source tarball is available at: https://launchpad.net/qemu-linaro/+milestone/2011.04-1 Binary builds of this qemu-linaro release are being prepared and will be available shortly for users of Ubuntu. Packages will be in the linaro-maintainers tools ppa: https://launchpad.net/~linaro-maintainers/+archive/tools/ More information on Linaro QEMU is available at: https://launchpad.net/qemu-linaro

14 years, 5 months

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Linaro GDB 7.2 2011-04 released

by Michael Hope

The Linaro Toolchain Working Group is pleased to announce the release of Linaro GDB 7.2. Linaro GDB 7.2 2011.04 is the fifth release in the 7.2 series. Based off the latest GDB 7.2, it includes a number of ARM-focused bug fixes. This release fixes: * LP: #684218 Failure to backtrace out of glibc system call stubs * LP: #667309 failed to single step over bad thumb->arm boundary * Fix accessing "fpscr" register The source tarball is available at: https://launchpad.net/gdb-linaro/+milestone/7.2-2011.04-0 More information on Linaro GDB is available at: https://launchpad.net/gdb-linaro -- Michael

14 years, 6 months

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Linaro GCC 4.5 and 4.6 2011-04 released

by Michael Hope

The Linaro Toolchain Working Group is pleased to announce the release of both Linaro GCC 4.5 and Linaro GCC 4.6. Linaro GCC 4.5 2011.04 is the ninth release in the 4.5 series. Based off the latest GCC 4.5.2+svn171921, it adds new optimisations, support for Android, and fixes for many of the issues found in the last month. Linaro GCC 4.6 2011.04 is the second release in the 4.6 series. Based off the latest GCC 4.6.0+svn171921, it is the first supported release of the new series and includes a significant number of mainstreamed patches from 4.5. Interesting changes in 4.6 include: * Updates to 4.6.0+r171921 * Adds conditional store sinking to the vectoriser * Brings in a significant number of the Linaro GCC 4.5 patches that are in mainline Interesting changes in 4.5 include: * Updates to 4.5.2+r172013 * Disables the shrink wrap optimisation by default * Adds support for swing-modulo scheduling (SMS) on ARM * Adds support for Android and the Bionic C library * Optimises -fvar-tracking, greatly reducing memory used when compiling large files (seen in QEMU) Fixes: * 'volatile' being ignored on volatile struct members * A potential register clobber in arm_negdi2 * An error in libgcc that prevented it being built with -Os * Multiple shrink wrap bugs (LP: #731665, 721023, 736081, 758082, 730860, 736439, 721023) * LP: #730440 incorrect immediate for movt (seen in Firebird) * LP: #728315 extension elimination pass mishandles subregs of promoted variables (seen on MIPS) * LP: #675347 volatile int causes inline assembly build failure (seen in Qt) SMS is an optimisation that works on innermost loops and reorders the instructions by overlapping different locations. An example is that the values for the next loop may be loaded during the current loop, making the values already ready when the next loop starts. SMS is disabled by default. To try it, add the options '-fmodulo-sched -fmodulo-sched-allow-regmoves'. The source tarball is available from: https://launchpad.net/gcc-linaro/+milestone/4.5-2011.04-0 https://launchpad.net/gcc-linaro/+milestone/4.6-2011.04-0 Downloads are available from the Linaro GCC page on Launchpad: https://launchpad.net/gcc-linaro -- Michael

14 years, 6 months

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[OT] ti-omap-tools - script for setting up DVSDK 3 with various toolchains

by AJ ONeal

Here's a script for installing TI's DVSDK 3: https://bitbucket.org/thayne/ti-omap-tools/src Works with - CodeSourcery - OpenEmbedded - Linaro It will download the bazillion dependencies scattered across TI's site and makes it easier to gut the DVSDK's hard-coded paths to work for your setup. The DVSDK 4 isn't used because it is completely different from the DVSDK 3 and is much more difficult to root the hard paths and checks out of. AJ ONeal

14 years, 6 months

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Question on compressed vmlinux .got and .bss sections

by Shawn Guo

Hi toolchain, kernel folks, I'm seeing an interesting thing on .got and .bss sections of arch/arm/boot/compressed/vmlinux, and really need your expertise to shed some lights. I have an uninitialized variable 'uart_base' defined in misc.c. static unsigned long uart_base; $ arm-linux-gnueabi-objdump -D arch/arm/boot/compressed/misc.o Disassembly of section .bss: 00000000 <uart_base>: 0: 00000000 andeq r0, r0, r0 00000004 <__machine_arch_type>: 4: 00000000 andeq r0, r0, r0 [...] And section layout looks like the following. $ arm-linux-gnueabi-objdump -h arch/arm/boot/compressed/vmlinux SECTIOINS { ... _etext = .; _got_start = .; .got : { *(.got) } _got_end = .; .got.plt : { *(.got.plt) } _edata = .; . = ALIGN(4); __bss_start = .; .bss : { *(.bss) } _end = .; ... } $ arm-linux-gnueabi-objdump -h arch/arm/boot/compressed/vmlinux arch/arm/boot/compressed/vmlinux: file format elf32-littlearm Sections: Idx Name Size VMA LMA File off Algn 0 .text 001c474c 00000000 00000000 00008000 2**5 CONTENTS, ALLOC, LOAD, READONLY, CODE 1 .got 00000028 001c474c 001c474c 001cc74c 2**2 CONTENTS, ALLOC, LOAD, DATA 2 .got.plt 0000000c 001c4774 001c4774 001cc774 2**2 CONTENTS, ALLOC, LOAD, DATA 3 .bss 00000020 001c4780 001c4780 001cc780 2**2 ALLOC 4 .stack 00001000 001c47a0 001c47a0 001cc780 2**0 ALLOC 5 .comment 0000002a 00000000 00000000 001cc780 2**0 CONTENTS, READONLY 6 .ARM.attributes 00000031 00000000 00000000 001cc7aa 2**0 CONTENTS, READONLY I'm able to see uart_base in vmlinux objdump ... $ arm-linux-gnueabi-objdump -t arch/arm/boot/compressed/vmlinux [relevant only, and sorted] 00000000 l d .text 00000000 .text 001c474c l d .got 00000000 .got 001c4774 l d .got.plt 00000000 .got.plt 001c4780 l d .bss 00000000 .bss 003968e4 g *ABS* 00000000 _image_size 001c474c g *ABS* 00000000 _got_start 001c4774 g *ABS* 00000000 _got_end 001c4780 g *ABS* 00000000 _edata 001c4780 g *ABS* 00000000 __bss_start 001c4780 l O .bss 00000004 uart_base 001c4798 g O .bss 00000004 malloc_ptr 001c478c g O .bss 00000004 output_ptr 001c479c g O .bss 00000004 malloc_count 001c4794 g O .bss 00000004 free_mem_end_ptr 001c4788 g O .bss 00000004 output_data 001c4784 g O .bss 00000004 __machine_arch_type 001c4790 g O .bss 00000004 free_mem_ptr 001c47a0 g *ABS* 00000000 _end ... but I can not see it in the zImage (all others in .bss seem still there). $ xxd arch/arm/boot/zImage | tail 01c4740: 3ef1 1400 be52 9f58 e468 3900 4c47 1c00 >....R.X.h9.LG.. ^_got_start (why is it?) 01c4750: 9847 1c00 1043 0000 8c47 1c00 9c47 1c00 .G...C...G...G.. ^malloc_ptr ^output_ptr 01c4760: 9447 1c00 080a 0000 8847 1c00 8447 1c00 .G.......G...G.. ^free_mem_end_ptr ^__machine_arch_type 01c4770: 9047 1c00 0000 0000 0000 0000 0000 0000 .G.............. ^free_mem_ptr The following is a run-time memdump at _got_start. Before recalculation: 9056304C: 001C474C 001C4798 00004310 001C478C 001C479C 001C4794 00000A08 001C4788 ^_got_start (why is it?) 9056306C: 001C4784 001C4790 00000000 00000000 00000000 EDFE0DD0 4C010000 38000000 After recalculation (for .bss entries, the delta is 9039EA50, for others in .got, delta is 9039E900): 9056304C: 9056304C 905631E8 903A2C10 905631DC 905631EC 905631E4 9039F308 905631D8 9056306C: 905631D4 905631E0 00000000 00000000 00000000 73FBC000 4C010000 38000000 QUESTION: Where is the .bss section of uart_base? Now, I remove the 'static' to have 'unsigned long uart_base', and dump the same stuff to compare. $ arm-linux-gnueabi-objdump -D arch/arm/boot/compressed/misc.o Disassembly of section .bss: 00000000 <__machine_arch_type>: 0: 00000000 andeq r0, r0, r0 00000004 <uart_base>: 4: 00000000 andeq r0, r0, r0 I'm able to see uart_base in vmlinux objdump ... $ arm-linux-gnueabi-objdump -t arch/arm/boot/compressed/vmlinux [relevant only, and sorted] 00000000 l d .text 00000000 .text 001c4720 l d .got 00000000 .got 001c474c l d .got.plt 00000000 .got.plt 001c4758 l d .bss 00000000 .bss 003968e4 g *ABS* 00000000 _image_size 001c4720 g *ABS* 00000000 _got_start 001c474c g *ABS* 00000000 _got_end 001c4758 g *ABS* 00000000 _edata 001c4758 g *ABS* 00000000 __bss_start 001c475c g O .bss 00000004 uart_base 001c4770 g O .bss 00000004 malloc_ptr 001c4764 g O .bss 00000004 output_ptr 001c4774 g O .bss 00000004 malloc_count 001c476c g O .bss 00000004 free_mem_end_ptr 001c4760 g O .bss 00000004 output_data 001c4758 g O .bss 00000004 __machine_arch_type 001c4768 g O .bss 00000004 free_mem_ptr 001c4778 g *ABS* 00000000 _end ... and I can also see it in the final zImage. $ xxd arch/arm/boot/zImage | tail 01c4710: 221f f1b3 3ef1 1400 be52 9f58 e468 3900 "...>....R.X.h9. 01c4720: 5c47 1c00 2047 1c00 7047 1c00 e442 0000 \G.. G..pG...B.. ^uart_base 01c4730: 6447 1c00 7447 1c00 6c47 1c00 140a 0000 dG..tG..lG...... 01c4740: 6047 1c00 5847 1c00 6847 1c00 0000 0000 `G..XG..hG...... 01c4750: 0000 0000 0000 0000 ........ Surely, it's in the run-time memdump. Before recalculation: 90563020: 001C475C 001C4720 001C4770 000042E4 001C4764 001C4774 001C476C 00000A14 ^uart_base 90563040: 001C4760 001C4758 001C4768 00000000 00000000 00000000 EDFE0DD0 4C010000 After recalculation: 90563020: 905631AC 90563020 905631C0 903A2BE4 905631B4 905631C4 905631BC 9039F314 90563040: 905631B0 905631A8 905631B8 00000000 00000000 00000000 EDFE0DD0 4C010000 So it looks the non-static ('g') uninitialized variable sits in .bss sections well, while static ('l') one is not there. Is this expected? How the static one is being addressed? Or ask where the offset for static one is stored? Any info or comments are appreciated. -- Regards, Shawn

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