turbo_decoder_sse_8bit segmentation fault
When testing OAI Ue in nos1 mode with iperf downlink data, a Segmentation fault is raised when frame_length in the turbo decoder is below 256. This is due to the structure of the Turbo Decoder in its optimized version (SSE instructions) for 8 bits LLR. This implementation cannot handle frame_length below 256.
To correct this issue a review of the Turbo Decoder shall be done
Note : there is an email thread on Eurecom mailing list regarding this issue (UE crashing with Segmentation fault) for more information
Note : There was a previous fix from Raymond on this subject. Tested version include this fix from Raymond Commit 0dc55ec8 . This fix has moved the issue to another point. (please find as attached file a run of the UE with segfault)UE_exec_1_.log
Autotest Impact :
All test cases with downlink iperf fail because at least for one of the run a SEGFAULT is raised (75% of the runs failed with a SEGFAULT within 3 minutes)
Detected in version :
TCL/develop1B : since 'harmony' merge due to small test coverage on iperf data with previous version. This bug might present for pre merge 'harmony' versions also.
SYRTEM propose a workaround -> mark all decoding with a frame_length < 256 with a CRC error. This will generate an extra BLER (due to implemenation).
THIS WORKAROUND IS NOT A FIX BUT ALLOW LTE-SOFTMODEM NOT TO STOP WITH A SEGFAULT (please find workaround as attached file - include also patch for issue #13 (closed))3gpplte_turbo_decoder_sse_8bit.patch