Discussion:
How to proceed with MiniDebugInfo
(too old to reply)
Alexander Larsson
2012-05-24 07:28:16 UTC
Permalink
I'm at a loss to how to proceed with the MiniDebugInfo work. I have
patches to rpmbuild that creates the compressed minidebuginfo putting
them in the main binaries, and I have patches to gdb that reads the
compressed debuginfo on demand.

However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
Jan Kratochvil
2012-05-24 07:35:59 UTC
Permalink
Post by Alexander Larsson
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
It is difficult to agree on something when you still have not accepted why
some people disagree with it.

I do not mind the size, as for example we lose already 5-10% by not using gold
(unused + duplicate template methods). I mind that in all aspects better
solution is ABRT and we should put more effort to it and not to some temporary
poor solutions. (This is very generalized to avoid the discussion again.)


Thanks,
Jan
Yanko Kaneti
2012-05-24 08:22:17 UTC
Permalink
Post by Jan Kratochvil
Post by Alexander Larsson
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
It is difficult to agree on something when you still have not accepted why
some people disagree with it.
I do not mind the size, as for example we lose already 5-10% by not using gold
(unused + duplicate template methods). I mind that in all aspects better
solution is ABRT and we should put more effort to it and not to some temporary
poor solutions. (This is very generalized to avoid the discussion again.)
And its difficult for me to understand how do you continue to claim "in
all aspects better" when comparing the two, An offline solution that
always produces at least something usable to a online one that requires
all-star alignment of circumstances to produce the perfect backtrace
result. There is no basis for one-or-the-other comparison.

IMHO its is a good thing for lightweight, kernel-like userspace
backtraces to become widely desseminated across the webs.

Regards
Yanko
Alexander Larsson
2012-05-24 09:07:06 UTC
Permalink
Post by Yanko Kaneti
Post by Jan Kratochvil
Post by Alexander Larsson
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
It is difficult to agree on something when you still have not accepted why
some people disagree with it.
I do not mind the size, as for example we lose already 5-10% by not using gold
(unused + duplicate template methods). I mind that in all aspects better
solution is ABRT and we should put more effort to it and not to some temporary
poor solutions. (This is very generalized to avoid the discussion again.)
And its difficult for me to understand how do you continue to claim "in
all aspects better" when comparing the two, An offline solution that
always produces at least something usable to a online one that requires
all-star alignment of circumstances to produce the perfect backtrace
result. There is no basis for one-or-the-other comparison.
IMHO its is a good thing for lightweight, kernel-like userspace
backtraces to become widely desseminated across the webs.
I obviously agree with this, and disagree with Jan, but I'd like to
avoid just repeating the previous discussion. The disagreement seems to
be about two things:

1) Any binary size increase is bad (as it affects cd sizes, etc)
2) The results of the MiniDebugInfo is not perfect, and
there is a theoretically perfect approach. So we should not
spend time/energy/space/bits/whatever on the non-perfect
appraoch.
However, the perfect approach has other disadvantages
due to being online/centralized, so I and others think
its worth having both.

The increased space is clearly a project global wide question that
probably has to be decided by Fesco.

The duplication of effort less so IMHO, as different people are doing
the work. If we don't do minidebug I will not be spending any resources
on the ABRT server anyway. So, not doing minidebug will not affect ABRT
positively, and doing it will not affect it negatively (in fact, it
might have a slight positive effect as it can use the low quality info
when offline). But still, as this is mainly a resource/project
management disagreement it might make sense to have Fesco look at it
too.
Jiri Moskovcak
2012-05-24 09:17:37 UTC
Permalink
Post by Alexander Larsson
Post by Yanko Kaneti
Post by Jan Kratochvil
Post by Alexander Larsson
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
It is difficult to agree on something when you still have not accepted why
some people disagree with it.
I do not mind the size, as for example we lose already 5-10% by not using gold
(unused + duplicate template methods). I mind that in all aspects better
solution is ABRT and we should put more effort to it and not to some temporary
poor solutions. (This is very generalized to avoid the discussion again.)
And its difficult for me to understand how do you continue to claim "in
all aspects better" when comparing the two, An offline solution that
always produces at least something usable to a online one that requires
all-star alignment of circumstances to produce the perfect backtrace
result. There is no basis for one-or-the-other comparison.
IMHO its is a good thing for lightweight, kernel-like userspace
backtraces to become widely desseminated across the webs.
I obviously agree with this, and disagree with Jan, but I'd like to
avoid just repeating the previous discussion. The disagreement seems to
1) Any binary size increase is bad (as it affects cd sizes, etc)
2) The results of the MiniDebugInfo is not perfect, and
there is a theoretically perfect approach. So we should not
spend time/energy/space/bits/whatever on the non-perfect
appraoch.
However, the perfect approach has other disadvantages
due to being online/centralized, so I and others think
its worth having both.
The increased space is clearly a project global wide question that
probably has to be decided by Fesco.
The duplication of effort less so IMHO, as different people are doing
the work. If we don't do minidebug I will not be spending any resources
on the ABRT server anyway. So, not doing minidebug will not affect ABRT
positively, and doing it will not affect it negatively (in fact, it
might have a slight positive effect as it can use the low quality info
when offline). But still, as this is mainly a resource/project
management disagreement it might make sense to have Fesco look at it
too.
In fact it will affect ABRT positively - the calltrace with function
names is a pretty good for duplicate checking, so ABRT will be able to
find the dupes in already filled bugzilla tickets without requiring the
full debuginfo.

Jirka
Alexander Larsson
2012-05-24 09:24:38 UTC
Permalink
Post by Jiri Moskovcak
Post by Alexander Larsson
The duplication of effort less so IMHO, as different people are doing
the work. If we don't do minidebug I will not be spending any resources
on the ABRT server anyway. So, not doing minidebug will not affect ABRT
positively, and doing it will not affect it negatively (in fact, it
might have a slight positive effect as it can use the low quality info
when offline). But still, as this is mainly a resource/project
management disagreement it might make sense to have Fesco look at it
too.
In fact it will affect ABRT positively - the calltrace with function
names is a pretty good for duplicate checking, so ABRT will be able to
find the dupes in already filled bugzilla tickets without requiring the
full debuginfo.
Well, theoretically it could do that by retracing the backtrace on the
server. It seems much simpler and more efficient to just do that locally
though, but this is partly where the disagreement is.
Jiri Moskovcak
2012-05-24 09:43:12 UTC
Permalink
Post by Alexander Larsson
Post by Jiri Moskovcak
Post by Alexander Larsson
The duplication of effort less so IMHO, as different people are doing
the work. If we don't do minidebug I will not be spending any resources
on the ABRT server anyway. So, not doing minidebug will not affect ABRT
positively, and doing it will not affect it negatively (in fact, it
might have a slight positive effect as it can use the low quality info
when offline). But still, as this is mainly a resource/project
management disagreement it might make sense to have Fesco look at it
too.
In fact it will affect ABRT positively - the calltrace with function
names is a pretty good for duplicate checking, so ABRT will be able to
find the dupes in already filled bugzilla tickets without requiring the
full debuginfo.
Well, theoretically it could do that by retracing the backtrace on the
server. It seems much simpler and more efficient to just do that locally
though, but this is partly where the disagreement is.
I know we could "retrace" the calltrace on a server to get the function
names, but for the use case we want to use it it's critical to have it
fast. And having it stored locally and available at the moment of crash
is imho faster than retracing it on a server.

I actually don't see a reason (except the space, but the numbers doesn't
look so horrible..) why not to have it. No one says it's going to be
used in tickets created by ABRT in bugzilla and no one says we're going
to force maintainers to work only with these "low quality" backtraces.
ABRT can still require the full backtrace to create a bz ticket and I
can easily imagine a situation where knowing just the function name
helps me to find a problem. So what's the worry about?

Jirka
Jan Kratochvil
2012-05-24 12:46:21 UTC
Permalink
Post by Alexander Larsson
2) The results of the MiniDebugInfo is not perfect, and
there is a theoretically perfect approach. So we should not
spend time/energy/space/bits/whatever on the non-perfect
appraoch.
However, the perfect approach has other disadvantages
due to being online/centralized, so I and others think
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

/ is not + here, other solutions require online connectivity but they do not
have to be centralized.
Post by Alexander Larsson
its worth having both.
There are many ways how to solve this problem, unfortunately nobody knows what
is your problem, there are too many close but still different problems in this
basket. You have delivered solution without stating the problem first.

(1) There are two kinds of developers:
(a) PC (instruction) of the crash only
(b) full context with parameters, variables and wanting even more.

(2) There are also two different kinds of developers:
(a) dependency on network services (like ABRT Retrace Server) is OK
(b) everything must work with full feature set even offline.

(3) And yet more two different kinds of developers:
(a) we must not upload anything for security reasons
(b) we can freely upload anything because Fedora already has no security.
- we already freely download+execute Mozilla binary plugins not reviewed
+ signed by Fedora Project, 99%(?) people install Flash anyway etc.

(4) And yet more two different kinds of developers:
(a) desktop ones who have thousands of BZs and ignore any ABRT BZ anyway
They are more interested in stats in which parts it crashes the most.
(b) at least Tools ones who check each BZ and have more problem that some
crashes repeat but they are not reproducible and even rich backtraces in
many cases do not contain enough info and it would be best to extend the
backtraces/bugreports even more.

There are various other solutions still keeping high quality backtraces such
as:

(x) Already stated fast core files upload to ABRT Retrace Server via gdbserver.
(y) With F-18 shorted .debug files
http://fedoraproject.org/wiki/Features/DwarfCompressor
downloading specific .debug.xz files can be much faster than whole
*-debuginfo.rpm.
(z) Symbol server for GDB - no need to download full debuginfos, GDB fetches
only parts on demand.

Maybe other solutions but it depends which of the 16 combinations of the (1),
(2), (3) and (4) use cases above you choose.


Regards,
Jan
Alexander Larsson
2012-05-24 13:34:28 UTC
Permalink
Post by Jan Kratochvil
There are many ways how to solve this problem, unfortunately nobody knows what
is your problem, there are too many close but still different problems in this
basket. You have delivered solution without stating the problem first.
I don't think there has to be a specific "problem". In fact, I think
Fedora shouldn't really care what *my* problem is. What is interesting
is: I have this feature; It has a certain cost (increase in size) and it
gives certain features. Is the price worth the features it gives?

Now, I don't want to repeat everything said before about what
minidebuginfo can do, but I'll give some short examples of things that
are nice to have and hard to do well without local debuginfo.

* Write backtraces to syslog on coredumps
* Allow ABRT to do better duplication matching (the ABRT developers even
want minidebuginfo!)
* Always get some minimal level of backtrace quality, even for rpms
built locally or from other repositories which are not availible
on the retrace servers. (Assuming they are built on a F18 or later
which has this feature.)
* Do system wide profiling and tracing without having to install a lot
of debuginfo.
* Help developers by always having at least some level of debuginfo,
even for e.g. uncommon dependencies that you don't typically have
debuginfo for, or when you don't have a network connection to get
debuginfo packages.

So, does these advantages outweigh the cost?
Jan Kratochvil
2012-05-24 14:19:15 UTC
Permalink
Post by Alexander Larsson
I don't think there has to be a specific "problem". In fact, I think
Fedora shouldn't really care what *my* problem is. What is interesting
is: I have this feature; It has a certain cost (increase in size) and it
gives certain features. Is the price worth the features it gives?
If your feature does not solve any problem it is just a bloat.
Post by Alexander Larsson
* Write backtraces to syslog on coredumps
backtrace is overloaded here. Minidebuginfo provides only bare unwinds.
Post by Alexander Larsson
* Allow ABRT to do better duplication matching (the ABRT developers even
want minidebuginfo!)
"do better" is too ambiguous and probably not right. Duplication matching can
be always done server-side. Minidebuginfo may give less load for ABRT servers
for example, this does not match the "do better" phrase.
Post by Alexander Larsson
* Always get some minimal level of backtrace quality, even for rpms
built locally or from other repositories which are not availible
on the retrace servers. (Assuming they are built on a F18 or later
which has this feature.)
I do not limit possible solutions only to retrace servers. Cores can be
backtraced even locally with full quality by (y) or (z) from my last mail.
Post by Alexander Larsson
* Do system wide profiling and tracing without having to install a lot
of debuginfo.
But a poor quality again, there won't be line-specific data for example.
Post by Alexander Larsson
* Help developers by always having at least some level of debuginfo,
even for e.g. uncommon dependencies that you don't typically have
debuginfo for,
debuginfo-install does everything on its own, user does not have to care.
Post by Alexander Larsson
or when you don't have a network connection to get
debuginfo packages.
This is the only valid point and pre-requisite of all your claims. But I do
not find a machine without network connectivity to be useful for anything.
Post by Alexander Larsson
So, does these advantages outweigh the cost?
Sure in no way.


Regards,
Jan
Jakub Jelinek
2012-05-24 14:25:43 UTC
Permalink
Post by Jan Kratochvil
"do better" is too ambiguous and probably not right. Duplication matching can
be always done server-side. Minidebuginfo may give less load for ABRT servers
for example, this does not match the "do better" phrase.
And the symbols for the duplication matching aren't as important,
it is enough if the reporting client transforms addresses in the unwind
address list into build-id + offset form, then it can be matched on the
server side too. Only if you want to fuzzy match bugreports from different
NVRs, then offsets are not useful and symbol names only sometimes useful.
But the build-id + offset form can be transformed into more detailed forms
on the server easily.

Jakub
Frank Ch. Eigler
2012-05-24 14:35:57 UTC
Permalink
Post by Jan Kratochvil
If your feature does not solve any problem it is just a bloat.
This overstates the case. Alex's proposal clearly solves some problems.

- FChE
Jan Kratochvil
2012-05-24 14:43:12 UTC
Permalink
Post by Frank Ch. Eigler
Post by Jan Kratochvil
If your feature does not solve any problem it is just a bloat.
This overstates the case. Alex's proposal clearly solves some problems.
This is just about wording.

My reaction was to:
I don't think there has to be a specific "problem".

Alexander talks about Minidebuginfo as about a feature but I find it to be
a bugfix category. Specifically to fix what ABRT should have delivered.
The primary goal are crash backtraces, tracing is not the Minidebuginfo goal.
Tracing is only misused as a way how to push Minidebuginfo through.

And bugfix without a problem is just that bloat.


Regards,
Jan
Richard W.M. Jones
2012-05-26 10:50:31 UTC
Permalink
Post by Jan Kratochvil
Post by Frank Ch. Eigler
Post by Jan Kratochvil
If your feature does not solve any problem it is just a bloat.
This overstates the case. Alex's proposal clearly solves some problems.
This is just about wording.
I don't think there has to be a specific "problem".
... but then he goes on to list 4 or 5 different features,
which are all nice to haves at a very small cost.

I'll add one more case, which seems to happen to me all the time:

- You're in IRC or email, and all the bug reporter has given you is a
random copy and paste from their terminal. They don't care to open
a bug; they don't much care about anything except getting a fix.

Minidebuginfo would help here.

Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://et.redhat.com/~rjones/virt-top
Jan Kratochvil
2012-05-26 14:12:59 UTC
Permalink
Post by Richard W.M. Jones
- You're in IRC or email, and all the bug reporter has given you is a
random copy and paste from their terminal. They don't care to open
a bug; they don't much care about anything except getting a fix.
Minidebuginfo would help here.
This is a bug of ABRT again. The crash should have been already reported
without asking anything. (Not going to discuss some security claims.)
You could just look up BZ(*) with the person's bugreport at that moment.
(*) Maybe such mass bugreports should not end up in BZ as the first place.


Regards,
Jan
Adam Williamson
2012-05-31 02:22:46 UTC
Permalink
Post by Jan Kratochvil
Post by Richard W.M. Jones
- You're in IRC or email, and all the bug reporter has given you is a
random copy and paste from their terminal. They don't care to open
a bug; they don't much care about anything except getting a fix.
Minidebuginfo would help here.
This is a bug of ABRT again. The crash should have been already reported
without asking anything. (Not going to discuss some security claims.)
You could just look up BZ(*) with the person's bugreport at that moment.
(*) Maybe such mass bugreports should not end up in BZ as the first place.
And how are you going to stop the user _then_ creating a manual report
with the random copy/pasted message _after_ the automatic report has
reported it without them noticing? How is the maintainer to know it's a
dupe without minidebuginfo? Your answer appears to be insufficient. :)
--
Adam Williamson
Fedora QA Community Monkey
IRC: adamw | Twitter: AdamW_Fedora | identi.ca: adamwfedora
http://www.happyassassin.net
Miloslav Trmač
2012-05-26 17:07:52 UTC
Permalink
Post by Richard W.M. Jones
- You're in IRC or email, and all the bug reporter has given you is a
 random copy and paste from their terminal.  They don't care to open
 a bug; they don't much care about anything except getting a fix.
Minidebuginfo would help here.
It seems you (and others in the thread) are hoping for an automatic
backtrace on any crash - I don't think that's in the currently
discussed scope.

Even with this feature you'll have to walk them through 1) enabling
core file creation, or finding the abrt-maintained core, and 2)
running gdb or abrt on the core. I'm not sure whether minidebuginfo
would make the situation actually simpler...
Mirek
Alexander Larsson
2012-05-28 17:57:48 UTC
Permalink
Post by Richard W.M. Jones
Post by Jan Kratochvil
Post by Frank Ch. Eigler
Post by Jan Kratochvil
If your feature does not solve any problem it is just a bloat.
This overstates the case. Alex's proposal clearly solves some problems.
This is just about wording.
I don't think there has to be a specific "problem".
... but then he goes on to list 4 or 5 different features,
which are all nice to haves at a very small cost.
- You're in IRC or email, and all the bug reporter has given you is a
random copy and paste from their terminal. They don't care to open
a bug; they don't much care about anything except getting a fix.
Minidebuginfo would help here.
Yeah, in general the goal of MiniDebugInfo is to raise the *minimum*
quality of all backtraces. If all the stars align we should be able to
have a system that gives perfect backtraces, using server magic in ABRT
and other things, but in all the cases where this for some reason
doesn't happen we should be able to *always* at least get full function
names in the backtrace instead of "???" (unless the stack is totally
corrupted of course).
Miloslav Trmač
2012-05-24 19:53:48 UTC
Permalink
Post by Alexander Larsson
I don't think there has to be a specific "problem". In fact, I think
Fedora shouldn't really care what *my* problem is. What is interesting
is: I have this feature; It has a certain cost (increase in size) and it
gives certain features. Is the price worth the features it gives?
It's only this simple if you are adding a new package.

Otherwise, there are two more questions:
- Is Fedora the right place for the feature?
- You contribute the initial code; do the people who would end up
maintaining it (if it is someone else than you) accept that code and
agree to maintain it?

For minidebuginfo, it is a "Fedora" decision whether to include
minidebuginfo in built RPMs - but the inclusion of gdb support is,
ideally, up to gdb upstream, or alternatively, up to gdb's package
maintainers (in this case, Jan and Sergio).

It's not infrequent that a feature happens in Fedora first and is
integrated upstream later - but it's not quite the preferred path.

Fairly frequently FESCo or FPC agrees to a feature and makes it
effectively required for all packages, even if some package
maintainers disagree (ideally after gathering input from interested
package maintainers first) - but that should IMHO be the case
primarily for system-wide features where individual agreement with all
affected parties is infeasible.


So, where to go from here? For the gdb change, I think the ideal case
would be to push the gdb support upstream (I have no idea what
upstream thinks, though), second best is to convince Jan and Sergio.
Only a third best is asking FESCo to overrule the gdb package
maintainers.

OTOH, FESCo will probably need to vote on the RPM packaging change in
any case, so it would be possible to start with this as well - with
the caveat that opposition from gdb package maintainers is an
additional risk for the feature and its acceptance.


My personal opinion is that this feature is net positive, but not
compelling enough to overrule the gdb maintainers and ask them to
maintain a Fedora-specific patch they don't like; of course, others on
FESCo may, and some probably do, disagree.
Mirek
Jan Kratochvil
2012-05-24 20:24:34 UTC
Permalink
Post by Miloslav Trmač
So, where to go from here? For the gdb change, I think the ideal case
would be to push the gdb support upstream (I have no idea what
upstream thinks, though), second best is to convince Jan and Sergio.
I have no problems accepting the patch to Fedora GDB (after some adjustments).
I just expect FESCo decision considering its pros and cons distro-wide.

I am trying to provide FESCo enough information for the feature as Alexander's
presentation of it seems biased to me.


Wrt upstreaming the patch to FSF GDB first it can be posted but I would
keep it for a release or two only downstream, it is simple enough patch, there
may be found some issues with its practical use (if any) etc.


Regards,
Jan
Alexander Larsson
2012-05-25 06:22:13 UTC
Permalink
Post by Jan Kratochvil
Wrt upstreaming the patch to FSF GDB first it can be posted but I would
keep it for a release or two only downstream, it is simple enough patch, there
may be found some issues with its practical use (if any) etc.
I agree with Jan. The patch is specifically meant to target a new form
of debuginfo that would (initially) only exist in Fedora. I don't think
it make sense to upstream that before its had some time to bake.
Panu Matilainen
2012-05-24 08:27:29 UTC
Permalink
Post by Alexander Larsson
I'm at a loss to how to proceed with the MiniDebugInfo work. I have
patches to rpmbuild that creates the compressed minidebuginfo putting
them in the main binaries, and I have patches to gdb that reads the
compressed debuginfo on demand.
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
Pass the feature to FESCo? For anything remotely controversial (and
judging by past discussion on the subject, this counts as one), you're
unlikely to get what amounts to an actual decision on fedora-devel...

- Panu -
Karel Klic
2012-05-24 15:06:44 UTC
Permalink
IMHO administrators would benefit much more from the minidebuginfo
feature than developers. The advantage for admins is that for every
crash the computer would also give a "name" of the crash. So it's
no longer just "httpd: Core dumped.", but you get a unique sequence
of functions (a "name") and you can talk about this particular crash
with other admins (it's no longer just "our webserver is randomly
crashing"), and search the Internet for other victims.

It would be very cool if the bottom of the stack (last few functions)
is printed to the terminal together with the usual "Core dumped."
message.

For developers, it is unappealing to attempt fixing a bug just from
an ordered list of function names.

Karel
Post by Alexander Larsson
Now, I don't want to repeat everything said before about what
minidebuginfo can do, but I'll give some short examples of things
that
are nice to have and hard to do well without local debuginfo.
* Write backtraces to syslog on coredumps
* Allow ABRT to do better duplication matching (the ABRT developers
even
want minidebuginfo!)
* Always get some minimal level of backtrace quality, even for rpms
built locally or from other repositories which are not availible
on the retrace servers. (Assuming they are built on a F18 or later
which has this feature.)
* Do system wide profiling and tracing without having to install a
lot
of debuginfo.
* Help developers by always having at least some level of debuginfo,
even for e.g. uncommon dependencies that you don't typically have
debuginfo for, or when you don't have a network connection to get
debuginfo packages.
Colin Walters
2012-05-24 16:09:17 UTC
Permalink
Post by Karel Klic
For developers, it is unappealing to attempt fixing a bug just from
an ordered list of function names.
Sometimes. Other times, it's all I need if I have other data at hand
(for example, the git log for the code that's crashing).
Panu Matilainen
2012-05-24 16:49:19 UTC
Permalink
Post by Colin Walters
Post by Karel Klic
For developers, it is unappealing to attempt fixing a bug just from
an ordered list of function names.
Sometimes. Other times, it's all I need if I have other data at hand
(for example, the git log for the code that's crashing).
Nod. There are always going to be cases where you wont be able to get
the "perfect backtrace", and a backtrace with nothing but function names
is helluva lot more useful than "it segfaulted."

- Panu -
Casey Dahlin
2012-05-24 17:20:15 UTC
Permalink
Post by Alexander Larsson
I'm at a loss to how to proceed with the MiniDebugInfo work. I have
patches to rpmbuild that creates the compressed minidebuginfo putting
them in the main binaries, and I have patches to gdb that reads the
compressed debuginfo on demand.
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
Just go do it. See who actually shows up to stop you.

--CJD
Jan Kratochvil
2012-05-24 17:27:03 UTC
Permalink
Post by Casey Dahlin
Just go do it. See who actually shows up to stop you.
I am sure this is significant enough distro change to require FESCo decision.


Regards,
Jan
Casey Dahlin
2012-05-24 19:42:17 UTC
Permalink
Post by Jan Kratochvil
Post by Casey Dahlin
Just go do it. See who actually shows up to stop you.
I am sure this is significant enough distro change to require FESCo decision.
Still cuts his workload down from convincing an open mailing list to
convincing 7 people.

--CJD
Alexander Larsson
2012-05-25 06:26:54 UTC
Permalink
Post by Casey Dahlin
Post by Alexander Larsson
I'm at a loss to how to proceed with the MiniDebugInfo work. I have
patches to rpmbuild that creates the compressed minidebuginfo putting
them in the main binaries, and I have patches to gdb that reads the
compressed debuginfo on demand.
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
Just go do it. See who actually shows up to stop you.
To actually get the debuginfo in the builds all I need is a minor patch
to the find-debuginfo.sh script in rpm-build. However, since the effect
of it is global it seems to me that its a wider decision than just the
maintainer of rpm-build.
Panu Matilainen
2012-05-25 07:10:25 UTC
Permalink
Post by Alexander Larsson
Post by Casey Dahlin
Post by Alexander Larsson
I'm at a loss to how to proceed with the MiniDebugInfo work. I have
patches to rpmbuild that creates the compressed minidebuginfo putting
them in the main binaries, and I have patches to gdb that reads the
compressed debuginfo on demand.
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
Just go do it. See who actually shows up to stop you.
To actually get the debuginfo in the builds all I need is a minor patch
to the find-debuginfo.sh script in rpm-build. However, since the effect
of it is global it seems to me that its a wider decision than just the
maintainer of rpm-build.
As long as the behavior is optional and configurable, just send the
patch to rpm-maint and we'll see. Fedora isn't the only consumer of rpm,
and somebody else might find it useful regardless of whether Fedora
wants to enable the thing or not.


- Panu -
Alexander Larsson
2012-06-11 10:14:46 UTC
Permalink
Post by Panu Matilainen
Post by Alexander Larsson
Post by Casey Dahlin
Post by Alexander Larsson
I'm at a loss to how to proceed with the MiniDebugInfo work. I have
patches to rpmbuild that creates the compressed minidebuginfo putting
them in the main binaries, and I have patches to gdb that reads the
compressed debuginfo on demand.
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
Just go do it. See who actually shows up to stop you.
To actually get the debuginfo in the builds all I need is a minor patch
to the find-debuginfo.sh script in rpm-build. However, since the effect
of it is global it seems to me that its a wider decision than just the
maintainer of rpm-build.
As long as the behavior is optional and configurable, just send the
patch to rpm-maint and we'll see. Fedora isn't the only consumer of rpm,
and somebody else might find it useful regardless of whether Fedora
wants to enable the thing or not.
Ok, here goes:

* rpm-minidebuginfo.patch
Patches find-debuginfo.sh and adds new _include_minidebuginfo option
defaulting to off
* redhat-rpm-config-minidebug.patch
Example patch that enables building minidebuginfo by default on Fedora

* 0001-configure.ac-Look-for-and-use-libzma-on-ELF-systems.patch
* 0002-Support-lzma-compressed-.gnu_debugdata-sections.patch
Gdb patches enabling on-demand lzma decompression of
the .gnu_debugdata section looking for separate debuginfo there.

With these patches all applied any rpm you build (that doesn't
explicitly disable debuginfo generation) will get xz compresses minimal
debug info that gdb will find automatically (unless the real debuginfo
is installed, then that will be used).

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Lennart Poettering
2012-05-29 19:49:14 UTC
Permalink
Post by Alexander Larsson
I'm at a loss to how to proceed with the MiniDebugInfo work. I have
patches to rpmbuild that creates the compressed minidebuginfo putting
them in the main binaries, and I have patches to gdb that reads the
compressed debuginfo on demand.
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
The right way is probably to write a feature page for F18 for it, and
then get it through Fedora 18 feature process. With FESCO accepting the
feature you should have all you need to get your work accepted by the
various stakeholders.

Lennart
--
Lennart Poettering - Red Hat, Inc.
Alexander Larsson
2012-06-05 09:08:11 UTC
Permalink
Post by Lennart Poettering
Post by Alexander Larsson
I'm at a loss to how to proceed with the MiniDebugInfo work. I have
patches to rpmbuild that creates the compressed minidebuginfo putting
them in the main binaries, and I have patches to gdb that reads the
compressed debuginfo on demand.
However, the whole thing is useless unless we agree that we want to
enable this by default. It seems some people like the idea, whereas
others disagree that its worth the increased binary size. It doesn't
look like either side is gonna be able to convince the other side, so
how do we get to a decision here?
The right way is probably to write a feature page for F18 for it, and
then get it through Fedora 18 feature process. With FESCO accepting the
feature you should have all you need to get your work accepted by the
various stakeholders.
I did write a feature page for it. Thats how these threads started.
Miloslav Trmač
2012-06-05 13:14:05 UTC
Permalink
Post by Alexander Larsson
Post by Lennart Poettering
The right way is probably to write a feature page for F18 for it, and
then get it through Fedora 18 feature process. With FESCO accepting the
feature you should have all you need to get your work accepted by the
various stakeholders.
I did write a feature page for it. Thats how these threads started.
It is in Category:FeaturePageIncomplete , which means FESCo will not
see it on its agenda. Please see
http://fedoraproject.org/wiki/Features/Policy/Process .
Mirek
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