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Re: FTBFS on armel: 'OV_CALLBACKS_STREAMONLY' undeclared

On 9/21/09, Daniel Kahn Gillmor <dkg@fifthhorseman.net> wrote:
>  I should note that i have some concerns about tremor on armel in general
>  that haven't been addressed by upstream (and i haven't been able to sort
>  out):
>   http://lists.xiph.org/pipermail/tremor/2009-April/001564.html
>  Maybe this update will cover those changes as well.

I just tried this, and it's doing a misaligned word access:

$ gdb ./ivorbisfile_example.armel
(gdb) run < *ogg > armel
Starting program:
< *ogg > armel

Bitstream is 2 channel, 44100Hz

Decoded length: 324300 samples
Encoded by: Xiph.Org libVorbis I 20070622

Program received signal SIGBUS, Bus error.
0x4004eaa0 in ov_read () from /usr/lib/libvorbisidec.so.1

To get the bus error you need to have
# echo 5 > /proc/cpu/alignment

the default setting (0) silently returns junk, specifically, the word
from addr&~3 rotated by (addr&3)*8 bits, which is less than useful.

Another setting, 3, catches the alignment trap, fakes "the right
thing" in the kernel and returns what you would get on a byte-aligned
machine; that would quickly tell you whether fixing the alignment
error will fix the problem.


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