# Progress #
o Upstream GDB
* ARM sim build failure with -fno-common
- Sent a patch to gdb-patches. Going through rounds of reviews.
* Patch reviewing and answering community questions.
o GDB
* GNU-644 - [GDB, AArch64] gdb.base/step-over-syscalls.exp failures
- Spent some more time with this in the hopes of understanding the
various failure modes. Still not clear if the kernel is doing the right
thing. It may be hard to adjust things on GDB's side, but i have a
couple patches solving some of the problems.
o Misc
* Updated personal information in the HR system.
# Plan #
o Upstream GDB
* Get approval for the fix to -fno-common build issues with ARM sim.
o GDB
* GNU-644 - [GDB, AArch64] gdb.base/step-over-syscalls.exp failures
- Engage with kernel folks for better understanding of signal
delivery scheme. Polish current fixes and submit for review.
o LLVM:
* Machine Outliner:
- Disabled asm statements.
- Added Helium LD/ST instructions support
- Adding testcases
o Misc
* Various meetings and discussions.
7 working days, then Thanksgiving.
[VIRT-262 # ARMv8.1-PAN Privileged Access Never]
Finished, still need to post.
[VIRT-273 # ARMv8.2-ATS1E1, AT S1E1R and AT S1E1W instruction variants ]
Finished, still need to post.
[VIRT-276 # ARMv8.2-UAO, PSTATE override of Unprivileged Load/Store ]
Finished, still need to post.
[VIRT-263 # ARMv8.1-VHE Virtual Host Extensions ]
FIXED! Welsh sprint with AJB; found and fixed two bugs.
Final bug causing guest kernel crash while booting fixed
upstream by Marc Zyngier vs ptrauth.
Will do some more thorough testing during rc4 and post
once the development phase opens up again.
[VIRT-327 # Richard's upstream QEMU work ]
Review of target/hexagon skeleton.
Review of arm dcpop patch set for beata.
Fixed a couple of arm translator bug for clyon.
Some investigation into a reported hppa-linux-user bug.
While I can reproduce locally, so far I have not tracked
down anything that I can prove is a translation bug.
r~
QEMU Tooling ([VIRT-252])
=========================
Extend gdbstub for SVE ([VIRT-281])
- worked on [v2 rebase addressing comments]
- posted {PATCH v2 00/14} gdbstub refactor and SVE support Message-Id:
<20191130084602.10818-1-alex.bennee(a)linaro.org>
[VIRT-281] https://projects.linaro.org/browse/VIRT-281
[working prototype]
https://github.com/stsquad/qemu/tree/gdbstub/sve-registers
[v2 rebase addressing comments]
https://github.com/stsquad/qemu/tree/gdbstub/sve-registers-v2
QEMU ARMv8.1 VHE ([VIRT_263])
=============================
- inaugural Welsh code sprint with rth
- found some new bugs, squashed some old bugs
- together with recent upstream fixes SUCCESS!
- can now boot a guest from a VHE enabled kernel :-)
[VIRT_263] https://projects.linaro.org/browse/VIRT-263
Upstream Work ([VIRT-109])
==========================
- posted {PULL for 4.2 0/3} a few vm-test fixes Message-Id:
<20191126120339.18059-1-alex.bennee(a)linaro.org>
- there are still niggling netbsd failures
- posted {PATCH for 4.2?} .travis.yml: drop xcode9.4 from build matrix
Message-Id: <20191127132430.3681-1-alex.bennee(a)linaro.org>
- investigation into [ARM HPC compiler triggered linux-user bug]
- may be 64k page related as couldn't reproduce on Ubuntu
- posted {PATCH v1 0/5} linux-user mmap debug cleanup Message-Id:
<20191128194603.24818-1-alex.bennee(a)linaro.org>
[ARM HPC compiler triggered linux-user bug]
https://bugs.launchpad.net/qemu/+bug/1853826
Other Activities
================
- published [QEMU Summit and KVM Forum trip report]
[QEMU Summit and KVM Forum trip report]
https://collaborate.linaro.org/display/CR/20191030+QEMU+Summit+and+KVM+Foru…
Absences
========
- 2nd Dec Holiday
Current Review Queue
====================
* {PATCH 0/4} python/qemu: New accel module and improvements
Message-Id: <20191115180829.10275-1-wainersm(a)redhat.com>
Added: <2019-11-28 Thu>
* {PATCH v2 0/2} Run tcg tests with tci on Travis
Message-Id: <20191128153525.2646-1-thuth(a)redhat.com>
Added: <2019-11-28 Thu>
* {PATCH 0/2} flush CPU TB cache in breakpoint_invalidate
Message-Id: <20191127220602.10827-1-jcmvbkbc(a)gmail.com>
Added: <2019-11-28 Thu>
* {RFC PATCH 00/10} hw/avr: Introduce the Arduino board
Message-Id: <20191128015030.27543-1-f4bug(a)amsat.org>
Added: <2019-11-28 Thu>
--
Alex Bennée
Progress:
* VIRT-65 [QEMU upstream maintainership]
- code review:
+ finally got back to the reset-refactoring patchset
and gave review on v5 of that. This is very nearly ready.
+ reviewed and got into 4.2 rc3 some patches from Marc Z
fixing some missing emulation/bugs that newer Linux
guest kernels trip over
+ rc3 out of the door; we will need an rc4, though
- more time consumed by office-move
thanks
-- PMM
[Morello]
Rebase of LLD against September CUCL update complete
- Painful due to LLD changing address layout (every test expected
value shifted), and a naming convention change.
- No functional changes needed to patch.
- Submitted static linking patches for review. Will send the dynamic
ones after all static linking has been merged.
Wrote up notes of Linaro Tech-leads Morello Q&A.
Misc:
Upstream LLD reviews
== Progress ==
* Out of office on Thursday
* LLVM 9.0.1
- Uploaded ARM & AArch64 binaries for rc1
- ARM: opened 2 bug reports (asan and cfi tests failing)
* Triaging check-lldb failures on AArch64 [LLVM-512]
- Opened a few more bug reports
- Got one nasty failure that I want to look into a bit more before
committing a patch XFAIL-ing everything so far
* Morello
- Got a VM working, built the toolchain, currently trying to build android
- Setting up all sorts of gerrit accounts and other minutiae
== Plan ==
* More of the same
Hi!
I've attempted to study the implementation of memcpy for 32-bit Arm cores in
Glibc (which is also found in arm-optimized-routines and first appeared in
Linaro's cortex-strings project), and I came across a peculiar snippet:
#ifdef USE_VFP
/* Magic dust alert! Force VFP on Cortex-A9. Experiments show
that the FP pipeline is much better at streaming loads and
stores. This is outside the critical loop. */
vmov.f32 s0, s0
#endif
This seems to imply that this NOP-like instruction affects CPU state and makes
the vldr/vstr instructions that follow use different datapaths that they might
otherwise? Can anyone shed more light on this, please?
I was able to trace history of this code back to revision 100 in cortex-strings
repository, where it appeared as part of a large rewrite by Will Newton:
https://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/rev…
The entire memcpy.S file in Arm optimized-routines repo can be found here:
https://github.com/ARM-software/optimized-routines/blob/master/string/arm/m…
Thanks!
Alexander
Hi Arnd,
I took a look on the stack usage issue in the kernel snippet you provided [1],
and as you have noted the most impact indeed come from -ftree-ch optimization.
It is enabled in all optimization levels besides -Os (since besides possible
increasing the stack usage it also might increase code side).
I am still fulling grasping what free-ch optimization does, but my understanding
so far is it tries to reorganize the loop for later loop optimization phases.
More specifically, what it ends up doing on the specific snippet is create extra
stack variables for the internal membber access in the inner loop (which in its
turns increase stack usage).
This is also why adding the compiler barrier inhibits the optimization, since it
prevents the ftree-ch to optimize the internal loop reorganization and it is
passed as is to later optimizations phases.
It is also a generic pass that affects all architecture, albeit the resulting
stack will depend on later passes. With GCC 9.2.1 I see the resulting stack
usage using -fstack-usage along with -O2:
arm 632
aarch64 448
powerpc 912
powerpc64le 560
s390 600
s390x 632
i386 1376
x86_64 784
Also, -fconserve-stack does not really help with this pass since ftree-ch does
not check the flag usage. The fconserve-stack currently only seems to effect
the inliner by setting both large-stack-frame and large-stack-frame-growth to
some conservative values.
The straightforward change I am checking is just to disable tree-ch optimization
if fconserve-stack is also enabled:
diff --git a/gcc/tree-ssa-loop-ch.c b/gcc/tree-ssa-loop-ch.c
index b894a7e0918..b14dd66257c 100644
--- a/gcc/tree-ssa-loop-ch.c
+++ b/gcc/tree-ssa-loop-ch.c
@@ -291,7 +291,8 @@ public:
{}
/* opt_pass methods: */
- virtual bool gate (function *) { return flag_tree_ch != 0; }
+ virtual bool gate (function *) { return flag_tree_ch != 0
+ && flag_conserve_stack == 0; }
/* Initialize and finalize loop structures, copying headers inbetween. */
virtual unsigned int execute (function *);
On powerpc64le with gcc master:
$ /home/azanella/gcc/gcc-git-build/gcc/xgcc -B /home/azanella/gcc/gcc-git-build/gcc -O2 ../stack_usage.c -c -fstack-usage && cat stack_usage.su
../stack_usage.c:157:6:mlx5e_grp_sw_update_stats 496 static
$ /home/azanella/gcc/gcc-git-build/gcc/xgcc -B /home/azanella/gcc/gcc-git-build/gcc -O2 ../stack_usage.c -c -fstack-usage -fconserve-stack && cat stack_usage.su
../stack_usage.c:157:6:mlx5e_grp_sw_update_stats 176 static
The reference for minimal stack usage is with -Os:
$ /home/azanella/gcc/gcc-git-build/gcc/xgcc -B /home/azanella/gcc/gcc-git-build/gcc -Os ../stack_usage.c -c -fstack-usage && cat stack_usage.su
../stack_usage.c:157:6:mlx5e_grp_sw_update_stats 32 static
I will try to check if also enable the same test for -fgcse and -free-ter
do make sense.
[1] https://godbolt.org/z/WKa-Bd
# Progress #
o Upstream GDB
* Make remote packet length in debugging output adjustable (as
opposed to fix to 512 bytes).
* Investigated ARM sim build issues with the GCC default moving to
-fno-common.
o GDB:
* GNU-644 - [GDB, AArch64] gdb.base/step-over-syscalls.exp failures
- No progress yet. Waiting for Kernel feedback.
* [RESOLVED] GNU-645 - gdbserver is not using SVE register
descriptions properly
- Pushed a fix upstream.
* GNU-170 - GDB BZ #21221 - gdb hangs while stepping an empty loop
- On hold for now.
o Friday off
# Plan #
o Upstream GDB
* Fox -fno-common build issues with ARM sim.
o GDB
* GNU-644 - [GDB, AArch64] gdb.base/step-over-syscalls.exp failures
- Continue working on a fix.
== This Week ==
* GCC
- PR92554: Spent some time triaging the issue, but gave up after
Richard posted better fix.
- PR89007: Addressing upstream suggestions.
- PR92608: Committed fix to trunk.
- GNU-583: Looking thru Kugan's patch and upstream discussion.
* Validation
- Submitted patch to add --gcc_patch_file option to abe.
- Submitted patch to remove --interactive from abe.
== Next Week ==
- Continue ongoing tasks
== Progress ==
* GCC:
- -mpure-code on v6m: sent an updated patch, waiting for approval.
* BFD Linker:
- non-contiguous memory support: partial prototype working on the
use-case, but causes regressions.
* GCC upstream validation:
- reported several issues
* misc:
- infra fixes / troubleshooting / reviews
== Next ==
* GCC: pure-code/v6m, handle feedback
* Binutils: support non-contiguous memory regions in linker
QEMU Tooling ([VIRT-252])
=========================
Extend gdbstub for SVE ([VIRT-281])
- worked on [v2 rebase addressing comments]
[VIRT-281] https://projects.linaro.org/browse/VIRT-281
[v2 rebase addressing comments]
https://github.com/stsquad/qemu/tree/gdbstub/sve-registers-v2
Upstream Work ([VIRT-109])
==========================
- general poking around and stress testing on the run up to release
- documented some outstanding issues [on the planning page]
- posted {PULL for rc3 0/5} a few doc and testing tweaks Message-Id:
<20191120105801.2735-1-alex.bennee(a)linaro.org>
- posted {PATCH for 4.2 v1 0/3} some tests/vm fixes Message-Id:
<20191122112231.18431-1-alex.bennee(a)linaro.org>
[VIRT-109] https://projects.linaro.org/browse/VIRT-109
[on the planning page] https://wiki.qemu.org/Planning/4.2
Other Activities
================
- finalising [draft of KVM Forum conference report]
- will publish on Monday once Beata adds the last note
[draft of KVM Forum conference report]
https://collaborate.linaro.org/pages/resumedraft.action?draftId=128647720
Completed Reviews [3/3]
=======================
{PATCH v2 0/6} Make the qemu_logfile handle thread safe.
Message-Id: <20191115131040.2834-1-robert.foley(a)linaro.org>
- CLOSING NOTE [2019-11-22 Fri 17:15]
Ad of v3 this is ready to go, just awaiting the tree to open again
Added: <2019-11-15 Fri>
{PATCH v3 0/6} Make the qemu_logfile handle thread safe.
Message-Id: <20191118211528.3221-1-robert.foley(a)linaro.org>
{PATCH 0/6} Enable Travis builds on arm64, ppc64le and s390x
Message-Id: <20191119170822.45649-1-thuth(a)redhat.com>
Current Review Queue
====================
* {PATCH 0/1} tests/vm: Allow to set path to qemu-img
Message-Id: <20191114134246.12073-1-wainersm(a)redhat.com>
Added: <2019-11-14 Thu>
* {PATCH v7 0/8} Acceptance test: Add "boot_linux" acceptance test
Message-Id: <20191104151323.9883-1-crosa(a)redhat.com>
Added: <2019-11-04 Mon>
* {RFC 0/3} tests/vhost-user-fs-test: add vhost-user-fs test case
Message-Id: <20191025100152.6638-1-stefanha(a)redhat.com>
Added: <2019-10-25 Fri>
* {PATCH v5 00/22} target/arm: Implement ARMv8.5-MemTag, system mode
Message-Id: <20191011134744.2477-1-richard.henderson(a)linaro.org>
Added: <2019-10-11 Fri>
--
Alex Bennée
[Morello]
- LLD finished pre-review refactoring and splitting up into reviewable chunks
- Implemented range-extension and interworking thunks to test
interaction with aligning .text to comply with Cheri Concentrate
- Answered some questions from Linaro tech-leads about Morello
Plans
- Rebase once CUCL merge has been completed and submit for review.
Planned Absences:
Christmas Holiday 16th December - 3rd January inclusive
Progress:
* VIRT-65 [QEMU upstream maintainership]
- code review:
+ Marc-Andre's series trying to get rid of QOM pointer properties
+ various minor bits for rc2
- unsuccessfully tried to work out why one of QEMU's test
cases asserts on BSD hosts only
- some time consumed by office-move
thanks
-- PMM
== Progress ==
* Triaging check-lldb failures on AArch64 [LLVM-512]
- Opened 4 bug reports
- One of them got a lot of attention so I was asked to upload more
logs/try various things
- Still have a couple of test failures to look into
* Morello
- First contact with the team
- Started looking at the internal docs
- Trying to build the existing toolchain
== Plan ==
* Figure out the current state of LLDB for Morello and what needs to be done
* Continue triaging LLDB failures
Dear Linaro,
Dear Linaro I'm using arm cortex A53 (mt6735 [part number]). But I do not know which tool-chain I have to use. I found your website https://www.linaro.org/downloads/ on internet. and my guess is aarch64-linux-gnu. can you please guide me through selecting a proper tool-chain.
Regards,
Saeed Djamali
# Progress #
o Upstream GDB
* More patch reviewing and answering questions.
o GDB:
* GNU-644 - [GDB, AArch64] gdb.base/step-over-syscalls.exp failures
- Managed to track this down all the way to the aarch64
single-stepping infrastructure in the kernel. Created reproduction steps
and sent an e-mail to linux-arm-kernel
- Also noticed a difference in the order in which SIGCHLD's are
delivered between x86_64 and aarch64. This confused GDB, which expects
the ordering it sees on x86_64. Working on a fix.
* Tweaked QEMU setup a little for SVE testing
* GNU-645 - gdbserver is not using SVE register descriptions properly
- Tracked down why gdbserver is not sending SVE register data back
to GDB. Working on a fix.
* GNU-170 - GDB BZ #21221 - gdb hangs while stepping an empty loop
- On hold for now.
# Plan #
o GDB
* GNU-644 - [GDB, AArch64] gdb.base/step-over-syscalls.exp failures
- Continue working on a fix.
* GNU-645 - gdbserver is not using SVE register descriptions properly
- Continue working on a fix.
[VIRT-262 # ARMv8.1-PAN Privileged Access Never]
Started, based on VHE patch set due to mmu_idx reorg therein.
Needs some minor re-work to handle Secure EL1.
[VIRT-273 # ARMv8.2-ATS1E1, AT S1E1R and AT S1E1W instruction variants ]
Started.
[VIRT-327 # Richard's upstream QEMU work ]
Some soft-freeze bug fixing of stuff that I broke this cycle.
Some patch review.
[Kernel]
Posted v7 of the ARMv8.5-RNG patch set. There's some significant
mis-communication going on between me and Mark Rutland; I have no
idea what he wants at this point...
[GCC]
Committed the base asm-flags patch set. Posted a follow-up
to un-break thumb1, and add tests for it.
r~
== This Week ==
* GCC
- PR89007: Posted patch upstream.
- GNU-583: Worked with Kugan, to reproduce LTO failure and verified
his patch fixes it.
- Bug 5479: Investigated with Maxim, most likely a glibc issue.
* Validation:
- Posted abe patch to add --gcc_patch_file option.
== Next Week ==
- Continue ongoing tasks.
Monday off
== Progress ==
* GCC:
- -mpure-code on v6m: answered questions about my patch. Almost OK
* Linker:
- started looking at implementing non-contiguous memory support
* GCC upstream validation:
- reported several issues
* misc:
- infra fixes / troubleshooting / reviews
== Next ==
* GCC: pure-code/v6m, handle feedback
* Binutils: support non-contiguous memory regions in linker
[Morello]
- Dynamic linking implementation complete and tests written based on
GNU ld output.
- Good progress on refactoring the work prior to breaking it down into
reviewable chunks. Have got a good idea of what I'd like the
implementation to look like.
TODO:
- Finish refactoring patches.
- Rebase into reviewable patches.
- Document the design decisions.
- Test on more than just the examples in the toolchain.
- Rebase on top of latest CUCL drop when merge is finished.
[Other]
LLVM-MC upstream review for the Linux Kernel.
QEMU Tooling ([VIRT-252])
=========================
QEMU plugin support ([VIRT-280])
- feature now merged in 4.2
- closed out a bunch of related JIRA cards
- API version now merged and this card is closed
Extend gdbstub for SVE ([VIRT-281])
- posted {RFC PATCH 00/11} gdbstub re-factor and SVE support
Message-Id: <20191115173000.21891-1-alex.bennee(a)linaro.org>
[VIRT-281] https://projects.linaro.org/browse/VIRT-281
[working prototype]
https://github.com/stsquad/qemu/tree/gdbstub/sve-registers
Upstream Work ([VIRT-109])
==========================
- posted {PULL 0/8} testing and tcg plugin api ver Message-Id:
<CAFEAcA_9AwoTE9zaKbiF6DkpN+O8LaEKGOct-m5S3yvFBHGK1g(a)mail.gmail.com>
- posted {PATCH for 4.2-rc2 v1 0/5} misc doc and testing fixes
Message-Id: <20191113115952.775-1-alex.bennee(a)linaro.org>
- posted {RFC PATCH} scripts/tap-driver: report "slow" tests (HACK)
Message-Id: <20191113142101.30280-1-alex.bennee(a)linaro.org>
Other Activities
================
- wrote [draft of KVM Forum conference report]
[draft of KVM Forum conference report]
https://collaborate.linaro.org/pages/resumedraft.action?draftId=128647720
Completed Reviews [5/5]
=======================
{PATCH 0/2} replace sysconf(_SC_PAGESIZE) with qemu_real_host_page_size
Message-Id: <20191015031350.4345-2-richardw.yang(a)linux.intel.com>
{PATCH v2 0/4} arm/aspeed: Watchdog and SDRAM fixes
Message-Id: <20191113005201.19005-1-joel(a)jms.id.au>
{kvm-unit-test PATCH 0/5} Improvements for the Travis CI
Message-Id: <20191113112649.14322-6-thuth(a)redhat.com>
{PATCH} target/arm: Clean up arm_cpu_vq_map_next_smaller asserts
Message-Id: <20191115131623.322-1-richard.henderson(a)linaro.org>
{PATCH v1 0/5} Make the qemu_logfile handle thread safe.
Message-Id: <20191112150105.2498-1-robert.foley(a)linaro.org>
Current Review Queue
====================
* {PATCH v2 0/6} Make the qemu_logfile handle thread safe.
Message-Id: <20191115131040.2834-1-robert.foley(a)linaro.org>
Added: <2019-11-15 Fri>
* {PATCH 0/1} tests/vm: Allow to set path to qemu-img
Message-Id: <20191114134246.12073-1-wainersm(a)redhat.com>
Added: <2019-11-14 Thu>
* {PATCH v7 0/8} Acceptance test: Add "boot_linux" acceptance test
Message-Id: <20191104151323.9883-1-crosa(a)redhat.com>
Added: <2019-11-04 Mon>
* {RFC 0/3} tests/vhost-user-fs-test: add vhost-user-fs test case
Message-Id: <20191025100152.6638-1-stefanha(a)redhat.com>
Added: <2019-10-25 Fri>
--
Alex Bennée
