* Re: ReBranch - a record-replay debugging tool
@ 2011-06-09 16:39 Nan Wang
2011-06-09 19:20 ` paawan oza
2011-06-10 5:51 ` Yao Qi
0 siblings, 2 replies; 23+ messages in thread
From: Nan Wang @ 2011-06-09 16:39 UTC (permalink / raw)
To: Pedro Alves, gdb
What I mean "control-flow only debugging" is:
Sometimes user only use GDB's control-flow functions, such as 'c', 'b',
'n', 's' ... to watch how the program get to the bug. He or she doesn't
care the variable name, the memory and some data-flow information.
ReBranch demands "control-flow only debugging" because it only records
every branch instruction. In current implementation (the modified
version of gdbserver), the replayer still need to create a process and
use ptrace to control it. When data-flow have error (caused by data-race
in multi threading situation), the ptraced process will generate
segfault for every instructions, which slows down the performance.
ReBranch have a GUI replayer -- ReBranchK -- which is a simple
control-flow-only debugging tool. ReBranchK doesn't really create the
process and debug it. It 'executes' the program virtually by reads the
log and shows corresponding source code. It implements 's', 'b' and 'c'
command. However, when writing ReBranchK, I found that, without stack
information, many useful control-flow command such as 'n' and 'bt' are
hard to be implemented. Therefore, I hope someone help me to put this
"control-flow only debugging" function into gdbserver.
> Can you clarify what do you mean by "control-flow only debugging"?
>
> (Note: I haven't had the time yet to read your document on ReBranch,
> so I don't really know how it works or why would you need gdbserver
> for replay)
>
^ permalink raw reply [flat|nested] 23+ messages in thread
* Re: ReBranch - a record-replay debugging tool
2011-06-09 16:39 ReBranch - a record-replay debugging tool Nan Wang
@ 2011-06-09 19:20 ` paawan oza
[not found] ` <bcaec5215b03b867ea04a5500b35@google.com>
2011-06-10 5:51 ` Yao Qi
1 sibling, 1 reply; 23+ messages in thread
From: paawan oza @ 2011-06-09 19:20 UTC (permalink / raw)
To: Nan Wang, Pedro Alves, gdb
Hi,
Is it something like you do an instrumentation in object code....mostly at all
control flows and system calls.
and record some things.
so indirectly you do not record every instruction, but you need to modify object
code by binary instrumentation.
but what I fail to understand is; what all do you record ?
Regards,
Oza.
----- Original Message ----
From: Nan Wang <pi3orama@gmail.com>
To: Pedro Alves <pedro@codesourcery.com>; gdb@sourceware.org
Sent: Thu, June 9, 2011 10:09:09 PM
Subject: Re: ReBranch - a record-replay debugging tool
What I mean "control-flow only debugging" is:
Sometimes user only use GDB's control-flow functions, such as 'c', 'b',
'n', 's' ... to watch how the program get to the bug. He or she doesn't
care the variable name, the memory and some data-flow information.
ReBranch demands "control-flow only debugging" because it only records
every branch instruction. In current implementation (the modified
version of gdbserver), the replayer still need to create a process and
use ptrace to control it. When data-flow have error (caused by data-race
in multi threading situation), the ptraced process will generate
segfault for every instructions, which slows down the performance.
ReBranch have a GUI replayer -- ReBranchK -- which is a simple
control-flow-only debugging tool. ReBranchK doesn't really create the
process and debug it. It 'executes' the program virtually by reads the
log and shows corresponding source code. It implements 's', 'b' and 'c'
command. However, when writing ReBranchK, I found that, without stack
information, many useful control-flow command such as 'n' and 'bt' are
hard to be implemented. Therefore, I hope someone help me to put this
"control-flow only debugging" function into gdbserver.
> Can you clarify what do you mean by "control-flow only debugging"?
>
> (Note: I haven't had the time yet to read your document on ReBranch,
> so I don't really know how it works or why would you need gdbserver
> for replay)
>
^ permalink raw reply [flat|nested] 23+ messages in thread* Re: ReBranch - a record-replay debugging tool
2011-06-09 16:39 ReBranch - a record-replay debugging tool Nan Wang
2011-06-09 19:20 ` paawan oza
@ 2011-06-10 5:51 ` Yao Qi
2011-06-10 6:39 ` pi3orama
1 sibling, 1 reply; 23+ messages in thread
From: Yao Qi @ 2011-06-10 5:51 UTC (permalink / raw)
To: gdb
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=GB2312, Size: 2352 bytes --]
On 06/10/2011 12:39 AM, Nan Wang wrote:
> What I mean "control-flow only debugging" is:
>
> Sometimes user only use GDB's control-flow functions, such as 'c', 'b',
> 'n', 's' ... to watch how the program get to the bug. He or she doesn't
> care the variable name, the memory and some data-flow information.
>
"control-flow only" is a good idea, and I think that is the reason why
your overhead, both on time and space, is so small. Good work!
> ReBranch demands "control-flow only debugging" because it only records
> every branch instruction. In current implementation (the modified
> version of gdbserver), the replayer still need to create a process and
> use ptrace to control it. When data-flow have error (caused by data-race
> in multi threading situation), the ptraced process will generate
IIUC, you have an assumption there that "during record, program runs
correctly, while during replace, program may run incorrectly",
otherwise, you can't find the problem by comparing control-flow.
The first half of assumption is OK, but the second half, which is more
important, might not be. Some research works are focusing on how to
expose/trigger non-deterministic program's faults. Your current
approach in replaying looks fine, but if you want to find more bugs in
replay, that might be the way to go.
> segfault for every instructions, which slows down the performance.
>
I don't understand why "process will generate segfault for every
instruction"?
> ReBranch have a GUI replayer -- ReBranchK -- which is a simple
> control-flow-only debugging tool. ReBranchK doesn't really create the
> process and debug it. It 'executes' the program virtually by reads the
> log and shows corresponding source code. It implements 's', 'b' and 'c'
> command. However, when writing ReBranchK, I found that, without stack
> information, many useful control-flow command such as 'n' and 'bt' are
> hard to be implemented. Therefore, I hope someone help me to put this
> "control-flow only debugging" function into gdbserver.
IIUC, you want to put your replayer function into gdbserver, in which,
record log file, and checkpoints are input. User can connect to this
special gdbsever to debug. Is that correct?
Generally speaking, gdbserver supports multiple archs, so is your record
log file format and checkpoints portable?
--
Yao (ÆëÒ¢)
^ permalink raw reply [flat|nested] 23+ messages in thread
* Re: ReBranch - a record-replay debugging tool
2011-06-10 5:51 ` Yao Qi
@ 2011-06-10 6:39 ` pi3orama
0 siblings, 0 replies; 23+ messages in thread
From: pi3orama @ 2011-06-10 6:39 UTC (permalink / raw)
To: Yao Qi; +Cc: gdb
>> ReBranch demands "control-flow only debugging" because it only records
>> every branch instruction. In current implementation (the modified
>> version of gdbserver), the replayer still need to create a process and
>> use ptrace to control it. When data-flow have error (caused by data-race
>> in multi threading situation), the ptraced process will generate
> IIUC, you have an assumption there that "during record, program runs
> correctly, while during replace, program may run incorrectly",
> otherwise, you can't find the problem by comparing control-flow.
>
> The first half of assumption is OK, but the second half, which is more
> important, might not be. Some research works are focusing on how to
> expose/trigger non-deterministic program's faults. Your current
> approach in replaying looks fine, but if you want to find more bugs in
> replay, that might be the way to go.
>
I don't think I have those assumption...
Yes, ReBranch doesn't trigger non-deterministic bugs. In fact it doesn't
know whether the program runs correctly or fault. ReBranch's job is to
faithfully record and replay the execution. If problems raise during
execution, ReBranch allows it to raise again in replay, and allows
developers to look into its control flow. Which converts
non-deterministic bugs into deterministic bugs. Developers can then
replay the program many time to find the bug. Without such a
record/replay tool, developers are hard to do this: when they notice the
bug and apply GDB, the bug will disappear.
>> segfault for every instructions, which slows down the performance.
>>
> I don't understand why "process will generate segfault for every
> instruction"?
>
Nearly every memory accessing instructions will segfault a while after a
new thread creation.
Currently, although all threads can be recorded, ReBranch is unable to
replay them simultaneously. Users can only replay and watch one thread
at a time. Therefore, because of the lost of IPC from shared memory,
sometimes ReBranch have to twist branch because the replayed thread
doesn't have the same data-flow as the original one. The effect can
propagate. For example, during original execution, a thread get a
pointer from another thread, then retrieve some data structure by it,
then do some computation. During replay, it won't get correct pointer
because there's no the other thread, but corresponding branch
instructions are twisted, so it will retrieve data from a invalid
address. A segfault is generated, then ReBranch intercepts it, let the
replay continue. So the following computation will be invalid, force
ReBranch twist more branches. In our experience, the propagate is very
fast. After the return from pthread_create function, the segfault
problem have already heavily slows down the replay speed.
>> ReBranch have a GUI replayer -- ReBranchK -- which is a simple
>> control-flow-only debugging tool. ReBranchK doesn't really create the
>> process and debug it. It 'executes' the program virtually by reads the
>> log and shows corresponding source code. It implements 's', 'b' and 'c'
>> command. However, when writing ReBranchK, I found that, without stack
>> information, many useful control-flow command such as 'n' and 'bt' are
>> hard to be implemented. Therefore, I hope someone help me to put this
>> "control-flow only debugging" function into gdbserver.
> IIUC, you want to put your replayer function into gdbserver, in which,
> record log file, and checkpoints are input. User can connect to this
> special gdbsever to debug. Is that correct?
Yes. Especially, I want gdbserver can handle stack frame information to
implement 'n', 'bt' and 'finish' commands.
> Generally speaking, gdbserver supports multiple archs, so is your record
> log file format and checkpoints portable?
I hope they are portable. However, currently checkpoint files and log
files are all platform specific. Checkpoint files contain some CPU
specific information; log files contain some platform specific system
call information.
^ permalink raw reply [flat|nested] 23+ messages in thread
* Re: ReBranch - a record-replay debugging tool
@ 2011-06-13 1:57 Robert Bu
2011-06-13 2:03 ` pi3orama
0 siblings, 1 reply; 23+ messages in thread
From: Robert Bu @ 2011-06-13 1:57 UTC (permalink / raw)
To: pi3orama; +Cc: gdb
Hi,
For data flow, recording syscall is not enough. There may be IO interaction.
I think your current implementation looks like a PC tracing, replaying tool.
Robert
>From: pi3orama <pi3orama@gmail.com>
>To: paawan oza <paawan1982@yahoo.com>
>Date: Fri, 10 Jun 2011 17:34:23 +0800
>Subject: Re: ReBranch - a record-replay debugging tool
>In multi-thread situation, nearly all data-flow information is lost
>because of propagation. However, in single thread situation, signal
>processing and system call results are all recorded and replayed, all
>data-flow info can still be restored.
>
>> ok got that point.
>> so in conclusion, any data-flow info which is reponsible for crash may not be
>> caught by rebranch, or there is a way ?
>>
>> Regards,
>> Oza.
^ permalink raw reply [flat|nested] 23+ messages in thread
* Re: ReBranch - a record-replay debugging tool
2011-06-13 1:57 Robert Bu
@ 2011-06-13 2:03 ` pi3orama
0 siblings, 0 replies; 23+ messages in thread
From: pi3orama @ 2011-06-13 2:03 UTC (permalink / raw)
To: Robert Bu; +Cc: gdb
Yes, you are right.
(P.S:
On the perspective of user processes, all IO interactions are come from
system calls, so for single thread processes, most of the time recording
system calls is enough for data-flow. The only exception I have seen is
vmsplice(): it temporary makes shared memory between 2 processes.)
> Hi,
>
> For data flow, recording syscall is not enough. There may be IO interaction.
> I think your current implementation looks like a PC tracing, replaying tool.
>
> Robert
>
>> From: pi3orama <pi3orama@gmail.com>
>> To: paawan oza <paawan1982@yahoo.com>
>> Date: Fri, 10 Jun 2011 17:34:23 +0800
>> Subject: Re: ReBranch - a record-replay debugging tool
>> In multi-thread situation, nearly all data-flow information is lost
>> because of propagation. However, in single thread situation, signal
>> processing and system call results are all recorded and replayed, all
>> data-flow info can still be restored.
>>
>>> ok got that point.
>>> so in conclusion, any data-flow info which is reponsible for crash may not be
>>> caught by rebranch, or there is a way ?
>>>
>>> Regards,
>>> Oza.
^ permalink raw reply [flat|nested] 23+ messages in thread
[parent not found: <bcaec5395f2aa367da04a5462782@google.com>]
* Re: ReBranch - a record-replay debugging tool
[not found] <bcaec5395f2aa367da04a5462782@google.com>
@ 2011-06-09 12:26 ` Pedro Alves
2011-06-09 12:54 ` pi3orama
2011-06-09 14:37 ` Joel Brobecker
0 siblings, 2 replies; 23+ messages in thread
From: Pedro Alves @ 2011-06-09 12:26 UTC (permalink / raw)
To: pi3orama; +Cc: gdb
On Thursday 09 June 2011 12:57:18, pi3orama@gmail.com wrote:
> Thank you for your advise. I have changed license, added a COPYING file in
> the code, and added copyright header into every source files.
Thanks a bunch!
One detail. Files that had been derived from other GPL files
should not lose the original copyright notice. Of course
you can _add_ a note on your own copyright. That is, e.g.,
on exception.h|c, I suggest something like:
/* Copyright (C) 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
2009, 2010, 2011 Free Software Foundation, Inc.
Copyright (C) 2009, 2010, 2011 Nan Wang
This file is part of ReBranch. Originally based on exceptions.c from GDB.
*/
(there may be other files, I really haven't checked)
Still very much looking forward for a high level outline of ReBranch's
record/replay strategy, and how it differs from GDB's target record. :-)
--
Pedro Alves
^ permalink raw reply [flat|nested] 23+ messages in thread* Re: ReBranch - a record-replay debugging tool
2011-06-09 12:26 ` Pedro Alves
@ 2011-06-09 12:54 ` pi3orama
2011-06-09 14:37 ` Joel Brobecker
1 sibling, 0 replies; 23+ messages in thread
From: pi3orama @ 2011-06-09 12:54 UTC (permalink / raw)
To: Pedro Alves; +Cc: gdb
I have add GDB's copyright notice back, you can check for it in the git
repository: https://gitorious.org/rebranch
A comparison of GDB record/replay and ReBranch has been added to the
google code site.
A pdf describe the mechanism of ReBranch has been uploaded to the site
and google doc:
http://rebranch.googlecode.com/hg/wiki/rebranch.pdf
https://docs.google.com/viewer?a=v&pid=explorer&chrome=true&srcid=0B1hummTQgSY1NTVhY2FkM2MtZDkxZi00ZDVhLTljNTQtMTZhMjZiMDI3ODZi&hl=en_US
Thank you for your kindly advise.
> On Thursday 09 June 2011 12:57:18, pi3orama@gmail.com wrote:
>> Thank you for your advise. I have changed license, added a COPYING file in
>> the code, and added copyright header into every source files.
> Thanks a bunch!
>
> One detail. Files that had been derived from other GPL files
> should not lose the original copyright notice. Of course
> you can _add_ a note on your own copyright. That is, e.g.,
> on exception.h|c, I suggest something like:
>
> /* Copyright (C) 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
> 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
> 2009, 2010, 2011 Free Software Foundation, Inc.
>
> Copyright (C) 2009, 2010, 2011 Nan Wang
>
> This file is part of ReBranch. Originally based on exceptions.c from GDB.
> */
>
> (there may be other files, I really haven't checked)
>
>
> Still very much looking forward for a high level outline of ReBranch's
> record/replay strategy, and how it differs from GDB's target record. :-)
>
^ permalink raw reply [flat|nested] 23+ messages in thread
* Re: ReBranch - a record-replay debugging tool
2011-06-09 12:26 ` Pedro Alves
2011-06-09 12:54 ` pi3orama
@ 2011-06-09 14:37 ` Joel Brobecker
2011-06-09 14:51 ` Pedro Alves
1 sibling, 1 reply; 23+ messages in thread
From: Joel Brobecker @ 2011-06-09 14:37 UTC (permalink / raw)
To: Pedro Alves; +Cc: pi3orama, gdb
> One detail. Files that had been derived from other GPL files
> should not lose the original copyright notice. Of course
> you can _add_ a note on your own copyright. That is, e.g.,
> on exception.h|c, I suggest something like:
>
> /* Copyright (C) 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
> 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
> 2009, 2010, 2011 Free Software Foundation, Inc.
>
> Copyright (C) 2009, 2010, 2011 Nan Wang
^^^^^^^^
If the files are going to be contributed to the GDB project,
I think we'll want the copyright to say FSF, no?
--
Joel
^ permalink raw reply [flat|nested] 23+ messages in thread* Re: ReBranch - a record-replay debugging tool
2011-06-09 14:37 ` Joel Brobecker
@ 2011-06-09 14:51 ` Pedro Alves
[not found] ` <BANLkTi=Mk0-PXb=7m0RZvEt7jegz17JXHw@mail.gmail.com>
0 siblings, 1 reply; 23+ messages in thread
From: Pedro Alves @ 2011-06-09 14:51 UTC (permalink / raw)
To: Joel Brobecker; +Cc: pi3orama, gdb
On Thursday 09 June 2011 15:36:51, Joel Brobecker wrote:
> > One detail. Files that had been derived from other GPL files
> > should not lose the original copyright notice. Of course
> > you can _add_ a note on your own copyright. That is, e.g.,
> > on exception.h|c, I suggest something like:
> >
> > /* Copyright (C) 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
> > 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008,
> > 2009, 2010, 2011 Free Software Foundation, Inc.
> >
> > Copyright (C) 2009, 2010, 2011 Nan Wang
> ^^^^^^^^
>
> If the files are going to be contributed to the GDB project,
> I think we'll want the copyright to say FSF, no?
The files in question are heavily modified and repurposed for
ReBranch. I was under the impression that the tool wanted to
remain a separate project. But if Nan is planning on assigning
the copyright to the FSF, yes. Of course, that'd be super cool,
as that way we could import bits into gdb/gdbserver proper
where it would make sense. (Not that I know which bits would
that be.) Nan, let us know if that's the case.
--
Pedro Alves
^ permalink raw reply [flat|nested] 23+ messages in thread
[parent not found: <1307602807.17016.ezmlm@sourceware.org>]
* ReBranch - a record-replay debugging tool
[not found] <1307602807.17016.ezmlm@sourceware.org>
@ 2011-06-09 7:23 ` pi3orama
2011-06-09 9:27 ` Pedro Alves
0 siblings, 1 reply; 23+ messages in thread
From: pi3orama @ 2011-06-09 7:23 UTC (permalink / raw)
To: gdb
Hi,
I developed a new record-replay tool -- ReBranch
(http://code.google.com/p/rebranch/), which focus on debugging
non-deterministic bugs. ReBranch can record the outgoing addresses of
every branch instructions, and recreate the whole control flow when
debugging. I have use it to fix some bugs in real open source projects
such as lighttpd and memcached. Unfortunately, few people knows this
project at google code, so nearly no one uses it.
I know that GDB has its own record-replay. However, I still believe
ReBranch is useful: ReBranch focus on recording in production systems,
its record performance is better than GDB's recording, it can record
whole program path (GDB can only record part of it), and most important,
ReBranch can be used in multi-threading programs.
I send this mail because I eagerly expect people to use my tool on their
developing process, and help me to improve it. And also, I want the
replay tool to be more integrated with GDB -- currently ReBranch use a
modified gdbserver to do the replay work, however, because ReBranch only
records control-flow, the replay performance is far from prefect.
Any suggestion is welcome. Thank you!
^ permalink raw reply [flat|nested] 23+ messages in thread* Re: ReBranch - a record-replay debugging tool
2011-06-09 7:23 ` pi3orama
@ 2011-06-09 9:27 ` Pedro Alves
2011-06-09 10:32 ` paawan oza
[not found] ` <4DF0A729.4070106@gmail.com>
0 siblings, 2 replies; 23+ messages in thread
From: Pedro Alves @ 2011-06-09 9:27 UTC (permalink / raw)
To: gdb; +Cc: pi3orama
On Thursday 09 June 2011 08:21:47, pi3orama wrote:
> Hi,
>
> I developed a new record-replay tool -- ReBranch
> (http://code.google.com/p/rebranch/), which focus on debugging
> non-deterministic bugs. ReBranch can record the outgoing addresses of
> every branch instructions, and recreate the whole control flow when
> debugging. I have use it to fix some bugs in real open source projects
> such as lighttpd and memcached. Unfortunately, few people knows this
> project at google code, so nearly no one uses it.
Nice!
>
> I know that GDB has its own record-replay. However, I still believe
> ReBranch is useful: ReBranch focus on recording in production systems,
> its record performance is better than GDB's recording, it can record
> whole program path (GDB can only record part of it), and most important,
> ReBranch can be used in multi-threading programs.
Can you outline ReBranch's record/replay strategy, and how it differs
from GDB's record?
> I send this mail because I eagerly expect people to use my tool on their
> developing process, and help me to improve it. And also, I want the
> replay tool to be more integrated with GDB -- currently ReBranch use a
> modified gdbserver to do the replay work, however, because ReBranch only
> records control-flow, the replay performance is far from prefect.
Since it based on modified gdbserver sources, making it a derivative
work, it must be GPLv3, right? I ask because the website says
MIT license.
--
Pedro Alves
^ permalink raw reply [flat|nested] 23+ messages in thread* Re: ReBranch - a record-replay debugging tool
2011-06-09 9:27 ` Pedro Alves
@ 2011-06-09 10:32 ` paawan oza
2011-06-09 13:05 ` pi3orama
[not found] ` <4DF0A729.4070106@gmail.com>
1 sibling, 1 reply; 23+ messages in thread
From: paawan oza @ 2011-06-09 10:32 UTC (permalink / raw)
To: pi3orama; +Cc: Pedro Alves, gdb
Hi,
in the site it says:
GDB
The replay is driven by GDB, nearly all GDB commands are useable.
Do I understand that recording is adopted differently ?
Regards,Oza.
________________________________
From: Pedro Alves <pedro@codesourcery.com>
To: gdb@sourceware.org
Cc: pi3orama <pi3orama@gmail.com>
Sent: Thu, June 9, 2011 2:57:20 PM
Subject: Re: ReBranch - a record-replay debugging tool
On Thursday 09 June 2011 08:21:47, pi3orama wrote:
> Hi,
>
> I developed a new record-replay tool -- ReBranch
> (http://code.google.com/p/rebranch/), which focus on debugging
> non-deterministic bugs. ReBranch can record the outgoing addresses of
> every branch instructions, and recreate the whole control flow when
> debugging. I have use it to fix some bugs in real open source projects
> such as lighttpd and memcached. Unfortunately, few people knows this
> project at google code, so nearly no one uses it.
Nice!
>
> I know that GDB has its own record-replay. However, I still believe
> ReBranch is useful: ReBranch focus on recording in production systems,
> its record performance is better than GDB's recording, it can record
> whole program path (GDB can only record part of it), and most important,
> ReBranch can be used in multi-threading programs.
Can you outline ReBranch's record/replay strategy, and how it differs
from GDB's record?
> I send this mail because I eagerly expect people to use my tool on their
> developing process, and help me to improve it. And also, I want the
> replay tool to be more integrated with GDB -- currently ReBranch use a
> modified gdbserver to do the replay work, however, because ReBranch only
> records control-flow, the replay performance is far from prefect.
Since it based on modified gdbserver sources, making it a derivative
work, it must be GPLv3, right? I ask because the website says
MIT license.
--
Pedro Alves
^ permalink raw reply [flat|nested] 23+ messages in thread* Re: ReBranch - a record-replay debugging tool
2011-06-09 10:32 ` paawan oza
@ 2011-06-09 13:05 ` pi3orama
0 siblings, 0 replies; 23+ messages in thread
From: pi3orama @ 2011-06-09 13:05 UTC (permalink / raw)
To: paawan oza; +Cc: Pedro Alves, gdb
I've changed the description in the site.
Only replay phase use gdbserver, recording phase is standalone. In fact,
there is a GUI tool (rebranchk.tcl) which allow users to replay without GDB.
> Hi,
>
> in the site it says:
>
>
> GDB
> The replay is driven by GDB, nearly all GDB commands are useable.
>
> Do I understand that recording is adopted differently ?
>
> Regards,Oza.
>
>
>
> ________________________________
> From: Pedro Alves <pedro@codesourcery.com>
> To: gdb@sourceware.org
> Cc: pi3orama <pi3orama@gmail.com>
> Sent: Thu, June 9, 2011 2:57:20 PM
> Subject: Re: ReBranch - a record-replay debugging tool
>
> On Thursday 09 June 2011 08:21:47, pi3orama wrote:
>> Hi,
>>
>> I developed a new record-replay tool -- ReBranch
>> (http://code.google.com/p/rebranch/), which focus on debugging
>> non-deterministic bugs. ReBranch can record the outgoing addresses of
>> every branch instructions, and recreate the whole control flow when
>> debugging. I have use it to fix some bugs in real open source projects
>> such as lighttpd and memcached. Unfortunately, few people knows this
>> project at google code, so nearly no one uses it.
> Nice!
>
>> I know that GDB has its own record-replay. However, I still believe
>> ReBranch is useful: ReBranch focus on recording in production systems,
>> its record performance is better than GDB's recording, it can record
>> whole program path (GDB can only record part of it), and most important,
>> ReBranch can be used in multi-threading programs.
> Can you outline ReBranch's record/replay strategy, and how it differs
> from GDB's record?
>
>> I send this mail because I eagerly expect people to use my tool on their
>> developing process, and help me to improve it. And also, I want the
>> replay tool to be more integrated with GDB -- currently ReBranch use a
>> modified gdbserver to do the replay work, however, because ReBranch only
>> records control-flow, the replay performance is far from prefect.
> Since it based on modified gdbserver sources, making it a derivative
> work, it must be GPLv3, right? I ask because the website says
> MIT license.
>
^ permalink raw reply [flat|nested] 23+ messages in thread
[parent not found: <4DF0A729.4070106@gmail.com>]
* Re: ReBranch - a record-replay debugging tool
[not found] ` <4DF0A729.4070106@gmail.com>
@ 2011-06-09 11:23 ` Pedro Alves
2011-06-09 12:06 ` pi3orama
0 siblings, 1 reply; 23+ messages in thread
From: Pedro Alves @ 2011-06-09 11:23 UTC (permalink / raw)
To: pi3orama; +Cc: gdb
On Thursday 09 June 2011 11:57:45, pi3orama wrote:
> I used to think that MIT license is compatible with GPLv3. I have
> changed the license. Sorry for the problem.
Thanks! It's compatible, but the GPL requires that the combination
is released under the same GNU GPL version. See:
<http://www.gnu.org/licenses/gpl-faq.html>
Can you also please update your LICENSE file in the sources? To comply
with the GPL you need to include a copy of the GPL license -- you'll
usually find it in a file named COPYING, e.g.,
see src/gdb/COPYING -- you can simply import that file into
your tree.
Also, could you please do a general look over the sources and
make sure not to lose the copyright header and license in files
based on FSF/GPL's sources? E.g, your src/host/exception.h and
src/host/exception.c are obviously based on
gdb's exceptions.h/exceptions.c.
You seem to have a lot of good stuff here. Looking forward to
have you cooperating with the GDB project!
--
Pedro Alves
^ permalink raw reply [flat|nested] 23+ messages in thread* Re: ReBranch - a record-replay debugging tool
2011-06-09 11:23 ` Pedro Alves
@ 2011-06-09 12:06 ` pi3orama
0 siblings, 0 replies; 23+ messages in thread
From: pi3orama @ 2011-06-09 12:06 UTC (permalink / raw)
Cc: gdb
Thank you for your advise. I have changed license, added a COPYING file
in the code, and added copyright header into every source files.
> On Thursday 09 June 2011 11:57:45, pi3orama wrote:
>> I used to think that MIT license is compatible with GPLv3. I have
>> changed the license. Sorry for the problem.
> Thanks! It's compatible, but the GPL requires that the combination
> is released under the same GNU GPL version. See:
>
> <http://www.gnu.org/licenses/gpl-faq.html>
>
> Can you also please update your LICENSE file in the sources? To comply
> with the GPL you need to include a copy of the GPL license -- you'll
> usually find it in a file named COPYING, e.g.,
> see src/gdb/COPYING -- you can simply import that file into
> your tree.
>
> Also, could you please do a general look over the sources and
> make sure not to lose the copyright header and license in files
> based on FSF/GPL's sources? E.g, your src/host/exception.h and
> src/host/exception.c are obviously based on
> gdb's exceptions.h/exceptions.c.
>
> You seem to have a lot of good stuff here. Looking forward to
> have you cooperating with the GDB project!
>
^ permalink raw reply [flat|nested] 23+ messages in thread
end of thread, other threads:[~2011-06-13 2:03 UTC | newest]
Thread overview: 23+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2011-06-09 16:39 ReBranch - a record-replay debugging tool Nan Wang
2011-06-09 19:20 ` paawan oza
[not found] ` <bcaec5215b03b867ea04a5500b35@google.com>
2011-06-10 1:55 ` pi3orama
2011-06-10 8:04 ` paawan oza
2011-06-10 8:15 ` pi3orama
2011-06-10 9:14 ` paawan oza
2011-06-10 9:36 ` pi3orama
2011-06-10 5:51 ` Yao Qi
2011-06-10 6:39 ` pi3orama
-- strict thread matches above, loose matches on Subject: below --
2011-06-13 1:57 Robert Bu
2011-06-13 2:03 ` pi3orama
[not found] <bcaec5395f2aa367da04a5462782@google.com>
2011-06-09 12:26 ` Pedro Alves
2011-06-09 12:54 ` pi3orama
2011-06-09 14:37 ` Joel Brobecker
2011-06-09 14:51 ` Pedro Alves
[not found] ` <BANLkTi=Mk0-PXb=7m0RZvEt7jegz17JXHw@mail.gmail.com>
2011-06-09 16:11 ` pi3orama
2011-06-09 16:20 ` Pedro Alves
[not found] <1307602807.17016.ezmlm@sourceware.org>
2011-06-09 7:23 ` pi3orama
2011-06-09 9:27 ` Pedro Alves
2011-06-09 10:32 ` paawan oza
2011-06-09 13:05 ` pi3orama
[not found] ` <4DF0A729.4070106@gmail.com>
2011-06-09 11:23 ` Pedro Alves
2011-06-09 12:06 ` pi3orama
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