From: "Marcin Kościelnicki" <koriakin@0x04.net>
To: gdb-patches@sourceware.org
Subject: Re: [PATCH 0/8] gdb/s390: Add regular and fast tracepoint support.
Date: Fri, 12 Feb 2016 11:04:00 -0000 [thread overview]
Message-ID: <56BDBC3D.2080605@0x04.net> (raw)
In-Reply-To: <1453637529-26972-1-git-send-email-koriakin@0x04.net>
A few updates on the status...
On 24/01/16 13:12, Marcin KoÅcielnicki wrote:
> This patchset adds support for regular and fast tracepoints on
> s390-ibm-linux-gnu and s390x-ibm-linux-gnu. It depends on the following
> yet-unlanded patches:
>
> - https://sourceware.org/ml/gdb-patches/2016-01/msg00597.html (for 31-bit
> fast tracepoint support)
> - https://sourceware.org/ml/gdb-patches/2016-01/msg00596.html (just
> a testsuite fix)
These two have landed by now.
> - https://sourceware.org/ml/gdb-patches/2016-01/msg00510.html (fixes
> setting a breakpoint and a tracepoint on the same location)
Still waiting for review.
>
> Patches 1-5 add working regular tracepoint support, patches 6-7 add
> working fast tracepoint support on top of that, and patch 8 makes fast
> tracepoints use compiled agent expressions.
I have updated the first 5 patches and hope to get them pushed first;
there are outstanding issues on #6 and #8 (doc comments, indents,
reading auxv from /proc) which I will fix soon (when I'm done with issue
(3) below).
>
> Patches 1 and 7 are in target-independent code, the remaining ones
> are in s390-specific code.
>
> It has been tested on s390-ibm-linux-gnu and s390x-ibm-linux-gnu on
> a z13 machine (without vector extensions). The parts handling vector
> extensions are untested. It has also been regression-tested on x86_64.
>
> There are 2 test failures still left in gdb.trace:
>
> - gdb.trace/unavailable.exp: print derived_whole has 4 failures on 64-bit
> only. The same failure happens on x86_64, so it's unlikely to be
> s390-specific.
> - gdb.trace/mi-tsv-changed.exp: create delete modify: tvariable $tvar3
> modified is an intermittent failure. It seems to be a race of some
> kind - in the failing runs, gdb shows the same messages, but in
> different order. I strongly suspect this is a target-independent
> issues that only happens on s390 due to timing factors.
>
> There are also three issues affecting s390 tracepoints that don't show
> up in the testsuite:
>
> 1. Target independent: tfile format doesn't contain target information
> (tdesc). While this affects all platforms with multiple tdescs
> (eg. x86_64 is unable to pull AVX registers from tfile for that
> reason), it horribly breaks 31-bit s390 with high GPRs - it has
> a completely different GPR layout from plain 31-bit s390, so the
> collected registers will be garbled. I suppose the proper fix to
> that would be to add tdesc information to tfile format. Unfortunately,
> I don't see a way to extend it in a backwards-compatible way.
This is fixed already.
> 2. Target independent: 32-bit (or 31-bit for us) IPA cannot be used with
> 64-bit gdbserver, due to communication involving lots of structs with
> pointer types. Fixing that would be quite involved, but possible
> (I don't suppose we have to maintain compatibility between IPA/gdbserver
> from different gdb versions?).
>
> 3. s390 specific: 31-bit gdbserver doesn't know about high GPRs, and
> cannot collect them if they're in use. Seems fixable with average
> effort. Unfortunately, fixing that will break tfile, unless (1)
> is fixed first...
Since (1) is fixed, I'm going to work on that one now.
> These three interact in bad ways, summarised below:
>
> - 64-bit linux, 64-bit gdbserver, 64-bit target: works OK, but you won't be
> able to see VX registers in tfile.
Works OK now, including VX in tfile.
>
> - 64-bit linux, 64-bit gdbserver, 31-bit target:
>
> - no fast tracepoint support due to (2)
> - tfile completely broken due to (1)
tfile should work now.
>
> - 64-bit linux, 31-bit gdbserver, 31-bit target:
>
> - works OK, but you won't be able to see VX registers or high GPRs at all,
> due to (3)
> - if (3) were fixed, tfile will be completely broken due to (1)
Second line no longer applies.
>
> - 31-bit linux, 31-bit gdbserver, 31-bit target: works OK
>
> In summary, there's no way at all to use fast tracepoints on 31-bit target
> if what you want to collect involves high GPRs. While there's support for
> it in the IPA, it's currently disabled, to match what gdbserver supports.
>
> Fast tracepoint support assumes z900+ CPU. The g5/g6 CPUs only have jump
> instuctions with +-64kiB of range, making them pretty much useless for
> our purposes, so not much loss here.
>
prev parent reply other threads:[~2016-02-12 11:04 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-24 12:12 Marcin Kościelnicki
2016-01-24 12:12 ` [PATCH 7/8] gdb.trace: Bump tspeed.exp timeout to 600 seconds Marcin Kościelnicki
2016-01-26 18:17 ` Andreas Arnez
2016-01-29 9:53 ` [PATCH] " Marcin Kościelnicki
2016-02-12 11:20 ` Yao Qi
2016-02-18 18:54 ` Marcin Kościelnicki
2016-01-24 12:12 ` [PATCH 2/8] gdb/s390: Fill write_guessed_tracepoint_pc hook Marcin Kościelnicki
2016-01-26 18:12 ` Andreas Arnez
2016-01-26 19:26 ` Marcin Kościelnicki
2016-01-29 18:57 ` Andreas Arnez
2016-02-07 14:00 ` [PATCH 2/8] gdb/s390: Fill supply_pseudo_pc hook Marcin Kościelnicki
2016-01-24 12:12 ` [PATCH 5/8] gdbserver/s390: Switch on tracepoint support Marcin Kościelnicki
2016-02-07 14:04 ` Marcin Kościelnicki
2016-02-22 7:38 ` [PATCH] " Marcin Kościelnicki
2016-03-04 10:39 ` [PATCH v3] " Marcin Kościelnicki
2016-03-15 18:41 ` [PATCH v4] " Marcin Kościelnicki
2016-03-22 9:16 ` Marcin Kościelnicki
2016-03-23 15:25 ` Andreas Arnez
2016-03-24 1:15 ` Marcin Kościelnicki
2016-03-29 18:31 ` Ulrich Weigand
2016-03-29 21:40 ` Marcin Kościelnicki
2016-03-29 21:40 ` [PATCH obv] gdb/NEWS: Add mention of s390*-linux tracepoints Marcin Kościelnicki
2016-03-30 2:49 ` Eli Zaretskii
2016-01-24 12:12 ` [PATCH 8/8] gdbserver/s390: Add support for compiled agent expressions Marcin Kościelnicki
2016-03-04 10:41 ` [PATCH v2] " Marcin Kościelnicki
2016-03-14 16:19 ` Andreas Arnez
2016-01-24 12:12 ` [PATCH 1/8] gdb: Add write_guessed_tracepoint_pc hook to gdbarch Marcin Kościelnicki
2016-01-26 14:58 ` Andreas Arnez
2016-02-07 13:59 ` [PATCH 1/8] gdb: Add supply_pseudo_pc " Marcin Kościelnicki
2016-02-16 18:28 ` Ulrich Weigand
2016-02-16 21:32 ` Marcin Kościelnicki
2016-02-18 10:35 ` [PATCH 1/2] gdb: Add guess_tracepoint_registers " Marcin Kościelnicki
2016-02-18 10:35 ` [PATCH 2/2] gdb/s390: Fill guess_tracepoint_registers hook Marcin Kościelnicki
2016-02-18 16:03 ` Ulrich Weigand
2016-02-18 16:36 ` [PATCH] " Marcin Kościelnicki
2016-02-18 16:48 ` Ulrich Weigand
2016-02-18 16:58 ` Marcin Kościelnicki
2016-02-18 11:38 ` [PATCH 1/2] gdb: Add guess_tracepoint_registers hook to gdbarch Luis Machado
2016-02-18 11:39 ` Marcin Kościelnicki
2016-02-18 11:45 ` [PATCH] " Marcin Kościelnicki
2016-02-18 15:40 ` Ulrich Weigand
2016-02-18 15:41 ` Marcin Kościelnicki
2016-02-18 15:58 ` Ulrich Weigand
2016-02-18 16:01 ` Marcin Kościelnicki
2016-02-18 16:06 ` Ulrich Weigand
2016-02-18 16:11 ` Marcin Kościelnicki
2016-02-18 16:13 ` Ulrich Weigand
2016-02-18 16:22 ` Marcin Kościelnicki
2016-01-24 12:12 ` [PATCH 3/8] gdb/s390: Fill pseudo register agent expression hooks Marcin Kościelnicki
2016-02-07 14:01 ` Marcin Kościelnicki
2016-02-25 19:23 ` Marcin Kościelnicki
2016-03-04 10:42 ` Marcin Kościelnicki
2016-03-11 2:20 ` Marcin Kościelnicki
2016-03-11 9:58 ` Andreas Arnez
2016-03-11 10:04 ` Marcin Kościelnicki
2016-01-24 12:12 ` [PATCH 4/8] gdb/s390: Fill gen_return_address hook Marcin Kościelnicki
2016-02-07 14:02 ` Marcin Kościelnicki
2016-02-25 19:23 ` Marcin Kościelnicki
2016-03-04 10:42 ` Marcin Kościelnicki
2016-03-11 11:20 ` Andreas Arnez
2016-03-11 11:35 ` Marcin Kościelnicki
2016-03-11 12:18 ` Andreas Arnez
2016-03-11 12:26 ` Marcin Kościelnicki
2016-03-11 15:31 ` Andreas Arnez
2016-03-11 15:44 ` Pedro Alves
2016-03-11 16:45 ` Andreas Arnez
2016-03-11 17:02 ` Pedro Alves
2016-03-11 18:17 ` Eli Zaretskii
2016-03-11 18:37 ` Pedro Alves
2016-03-11 19:34 ` Eli Zaretskii
2016-03-15 11:11 ` Pedro Alves
2016-03-15 11:23 ` Andreas Arnez
2016-03-15 11:30 ` Pedro Alves
2016-03-11 18:07 ` Eli Zaretskii
2016-03-13 9:53 ` Marcin Kościelnicki
2016-03-14 10:07 ` Andreas Arnez
2016-01-24 12:13 ` [PATCH 6/8] gdbserver/s390: Add fast tracepoint support Marcin Kościelnicki
2016-01-25 14:34 ` Antoine Tremblay
2016-02-19 13:41 ` Marcin Kościelnicki
2016-02-19 14:41 ` Antoine Tremblay
2016-03-04 10:40 ` [PATCH v2] " Marcin Kościelnicki
2016-03-14 16:19 ` Andreas Arnez
2016-03-14 16:25 ` Marcin Kościelnicki
2016-01-25 13:27 ` [PATCH 0/8] gdb/s390: Add regular and " Antoine Tremblay
2016-01-25 13:56 ` Pedro Alves
2016-01-25 14:28 ` Marcin Kościelnicki
2016-01-25 15:57 ` Pedro Alves
2016-01-25 16:03 ` Marcin Kościelnicki
2016-02-12 11:04 ` Marcin Kościelnicki [this message]
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