* [regression] gdb 7.11 breaks rr
@ 2016-05-16 22:06 Kyle Huey
2016-05-17 16:27 ` Pedro Alves
0 siblings, 1 reply; 3+ messages in thread
From: Kyle Huey @ 2016-05-16 22:06 UTC (permalink / raw)
To: gdb; +Cc: rr-dev, Pedro Alves
(Resending because the gdb list rejects HTML mail, sorry for duplicates)
Steps to reproduce:
1. Clone rr from https://github.com/mozilla/rr.git
2. Build rr rev 8566e3038892
3. ./bin/rr record ./bin/reverse_continue_process_signal
4. ./bin/rr replay -d /path/to/gdb-7.11
5. c
6. Once, the program has reached the SIGKILL, b 22
7. rc
Instead of reversing to the fork on line 22, rr will stop again at the
SIGKILL.
Beginning with [0] gdb seems to forget which direction execution is heading
in when a signal is reported by the gdb server. When gdb resumes execution
after deciding to ignore the signal it sends a vCont instead of a bc to the
gdb server, causing rr to execute forwards again.
This was fixed after the release of gdb 7.11 by [1]. I verified that
cherry-picking this commit on top of the gdb-7.11-release tag also fixes
rr. Could we get this commit backported for a 7.11.1? rr's reverse
execution features are largely unusable with complex programs (e.g.
Firefox) because of this bug.
Thanks,
- Kyle
[0]
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=0b333c5e7d6c3fc65d37ffa11bd21ba52c4adb25
[1]
https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=3a00c80277a54abe0b286a6e8babc8fe50120205
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [regression] gdb 7.11 breaks rr
2016-05-16 22:06 [regression] gdb 7.11 breaks rr Kyle Huey
@ 2016-05-17 16:27 ` Pedro Alves
2016-05-17 18:02 ` Kyle Huey
0 siblings, 1 reply; 3+ messages in thread
From: Pedro Alves @ 2016-05-17 16:27 UTC (permalink / raw)
To: Kyle Huey, gdb; +Cc: rr-dev
On 05/16/2016 11:06 PM, Kyle Huey wrote:
> This was fixed after the release of gdb 7.11 by [1]. I verified that
> cherry-picking this commit on top of the gdb-7.11-release tag also fixes
> rr. Could we get this commit backported for a 7.11.1?
It actually was already, at the time:
https://sourceware.org/ml/gdb-patches/2016-04/msg00277.html
Git commit 6b9ef0d488c556339aea7b095ef7a9b6bf6b1af1.
Try the gdb-7.11-branch branch (where 7.11.1 will be released from),
instead of the 7.11 release tag, which is frozen.
Thanks,
Pedro Alves
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [regression] gdb 7.11 breaks rr
2016-05-17 16:27 ` Pedro Alves
@ 2016-05-17 18:02 ` Kyle Huey
0 siblings, 0 replies; 3+ messages in thread
From: Kyle Huey @ 2016-05-17 18:02 UTC (permalink / raw)
To: Pedro Alves; +Cc: gdb, rr-dev
On Tue, May 17, 2016 at 9:27 AM, Pedro Alves <palves@redhat.com> wrote:
>
> On 05/16/2016 11:06 PM, Kyle Huey wrote:
>
> > This was fixed after the release of gdb 7.11 by [1]. I verified that
> > cherry-picking this commit on top of the gdb-7.11-release tag also fixes
> > rr. Could we get this commit backported for a 7.11.1?
>
> It actually was already, at the time:
>
> https://sourceware.org/ml/gdb-patches/2016-04/msg00277.html
>
> Git commit 6b9ef0d488c556339aea7b095ef7a9b6bf6b1af1.
>
> Try the gdb-7.11-branch branch (where 7.11.1 will be released from),
> instead of the 7.11 release tag, which is frozen.
>
> Thanks,
> Pedro Alves
>
Yes, the gdb-7.11-branch branch works too. Great!
- Kyle
^ permalink raw reply [flat|nested] 3+ messages in thread
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2016-05-16 22:06 [regression] gdb 7.11 breaks rr Kyle Huey
2016-05-17 16:27 ` Pedro Alves
2016-05-17 18:02 ` Kyle Huey
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