[Box Backup] Workaround for struct packing problem on ARM processors (was: Another wish for 2011)

Felix Werner Felix.Werner at kit.edu
Fri Feb 25 07:53:54 GMT 2011


On Thursday February 24 2011 23:29:37 Chris Wilson wrote:
> Hi Leif,
> 
> On Wed, 23 Feb 2011, Chris Wilson wrote:
> > On Sat, 12 Feb 2011, Leif Linderstam wrote:
> >>  Now I have made a suggested workaround for the struct packing problem.
> >>  As far as I know the problem only manifests itself in the source file
> >>  BackupStoreDirectory.cpp. The packing directive is ignored by the
> >>  compiler and the struct en_StreamFormat is therefore automatically
> >>  padded to 36 bytes, while on other platforms its size is only 34.
> > 
> > Thank you for your diligence and patience in testing this and developing
> > a workaround.
> > 
> > I would be very interested to know why the packing directive is ignored
> > on your platform, as this may have other consequences that are not
> > currently obvious to us, and may cause other code to fail in subtle
> > ways.
> > 
> > Did you find any documentation as to why the packing directive is
> > ignored by GCC on ARM?
> 
> Which version of GCC are you using? Could it possibly be a bug that's
> already been reported and fixed in a more recent GCC, like this one?

Hi Chris,

just as a note, I have built Box Backup on an ARMv5tel using GCC 4.4.3 
successfully. The server communicates smoothly with a client running on AMD64. 
So this might actually be a problem in Leif's toolchain.

Cheers,
  Felix

> 
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=394703
> 
> Cheers, Chris.



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