Hello users

On Sat, Apr 25, 2009 at 2:31 PM, Derek Spadaro <[email protected]> wrote:
> The easiest way I have reproduced this problem is that /bin/busybox
> seg faults the first time running it from a newly mounted aufs root.
> It is using gcc 4.2.3 and uClibc 0.30.0, built with buildroot
> (buildroot.uclibc.org).  It never happens when the file exists first
> in the r/w branch, only after first copy-up from r/o branch.  At this
> point I am assuming it has something to do with uClibc and aufs
> interactions.  I need to find a suitable glibc to re-build without
> uClibc.  That is a non-trivial effort which I will keep trying to work
> on.  Also I will get gdb on it and hopefully learn more.
>
> In terms of reproduction you may want to wait since it is also
> possible to be a uClibc issue rather than aufs, and quite frankly
> working with uClibc, even with buildroot, can be a bit of a pain if
> you have not before.  I appreciate the help though.
> Derek
>
> On Wed, Apr 22, 2009 at 10:11 PM,  <[email protected]> wrote:
>>
>> Derek Spadaro:
>>> Thank you for the patch suggestion, but it did not change the
>>> behaviour in this case.  Now also I am less sure about the
>>> relationship to shared libraries, as this would not explain why simply
>>> touching the executable helps.  Touch doesn't run the program, nor
>>> does it load any of the program's shared libraries, so I am not sure
>>> what it is doing to fix it; or what it is fixing, for that matter.
>>
>> touch(1) causes internal file copy-up, and it is related to aufs
>> mmap(2).
>> In mmap(2), which branch the file exists is important to aufs and the
>> previous patch changes its behaviour.
>> Currently I am guessing your problem is related to copy-up. The first
>> execution might occur copyup (and aborted). In the second time, no
>> copyup occured since the file was already copied-up.
>> touch(1) before execution surely makes file copied-up, and next
>> execution succeeded.
>>
>> I am afraid that I have to read source files in userspace, since all
>> systemcalls in your strace log succeeded and the segv happend in
>> userspace.
>> I am new to uClibc and know nothing about /usr/occam/bin/pdcpshim
>> either. How can I get source files of them (the exact version which you
>> are using) to reproduce the problem?
>>
>> By the way, if you stop using uClibc and replace it by glibc, can you
>> reporduce the problem?
>>
>>
>> J. R. Okajima
>>
>

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