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Re: fsvs 1.1.17 on sheevaplug, debian squeeze - segfault fixed by no-op patch

Author pmarek
Full name P.Marek
Date 2010-11-26 23:41:53 PST
Message Hello Seth!

> First off - I appreciate FSVS so much; it's been a lifesaver helping me
> figure out how I messed up my postfix install, or why apache is suddenly
> unhappy. I routinely install it on every *nix box I stand up.
Thank you. Yes, it's helpful sometimes.

> I wanted to drop you a line to confirm the strange results
...
> I then added
> your patch from
> http://www.mail-arch​ive.com/users@fsvs.t​igris.org/msg00826.h​tml
> (manually applied, since the debian line numbers are slightly off your
> baseline for the patch) - and somehow it suddenly worked?
>
 > All I can think is that this is uncovering a bug in the toolchain - I
> simply can't see why adding some debug printfs would change the
> semantics of the program
Yes, this surely looks like a compiler bug.


> Anyway, it looks like my home-built package is working fine now
Well, if it's already self-compiled anyway, you might as well use FSVS 1.2.2 - "status"
is much faster, and it has a few bugs fixed, too.


Regards,

Phil

--
Versioning your /etc, /home or even your whole installation?
             Try fsvs (fsvs.tigris.org)!

fsvs 1.1.17 on sheevaplug, debian squeeze - segfault fixed by no-op patch

Author Seth Porter <symmetry at pobox dot com>
Full name Seth Porter <symmetry at pobox dot com>
Date 2010-11-26 15:33:53 PST
Message First off - I appreciate FSVS so much; it's been a lifesaver helping me
figure out how I messed up my postfix install, or why apache is suddenly
unhappy. I routinely install it on every *nix box I stand up.

I wanted to drop you a line to confirm the strange results reported in
http://www.mail-arch​ive.com/users@fsvs.t​igris.org/msg00829.h​tml ("fsvs
on Emdebian"). I'm running Debian Squeeze on a Marvell SheevaPlug
('armel' architecture). The version in squeeze is 1.1.17-1, and
segfaults in direnum just as Lukas indicated in that thread (faults on
fsvs stat or fsvs commit).

I built the package locally from the debian source, with --enable-debug
added to the ./configure line, and it still segfaulted. I then added
your patch from
http://www.mail-arch​ive.com/users@fsvs.t​igris.org/msg00826.h​tml
(manually applied, since the debian line numbers are slightly off your
baseline for the patch) - and somehow it suddenly worked?

All I can think is that this is uncovering a bug in the toolchain - I
simply can't see why adding some debug printfs would change the
semantics of the program (especially since it works even without -d!).
Either I'm missing something in that patch, or there's something truly
bizarre going on (a broken optimization?) and adding the conditional
print is enough to bring the compiler back to sanity?

Anyway, it looks like my home-built package is working fine now, but I
thought I'd pass along a confirmation of this pretty bizarre symptom. If
you're interested I'd be happy to try experiments locally, though the
Sheevaplug is pretty resource-bound for any serious debugging effort (I
was happy just to get the compilation working without having to set up a
cross-compile chain).

Thanks,
Seth
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