Re: [Discuss-gnuradio] Segfault with volk_32fc_32f_dot_prod_32fc_a_avx

[Andy Walls]

>                              From: 
> devin kelly
>                           Subject: 
> Re: [Discuss-gnuradio] Segfault
> with
> volk_32fc_32f_dot_prod_32fc_a_avx
>                              Date: 
> Wed, 7 Dec 2016 10:18:32 -0500
> 
> ______________________________________________________________________


> I think I've found part of the problem:
> 
> 
> Looking here (on frame 2 in gdb):
> 
> https://github.com/gnuradio/gnuradio/blob/master/gr-digital/lib/pfb_clock_sync_ccf_impl.cc#L465
> 
> 
> 
> This is the line where filter is called (which is where the segfault
> occurs):
> 
> 
> d_filters[d_filtnum]->filter(&in[count+d_out_idx])
> 
> 
> From GDB I can see
> 
> 
> d_filtnum = 0
> count = -67108696
> d_out_idx = 0
> 

This is a garbage-in, garbage-out problem I've seen exactly before with
other blocks and the PFB clock sync block.

1. Check to make sure that your filter taps don't trace out a function
that has discontinuities or flat spots (i.e. a square pulse), and the
PFB clock sync algorithms can't handle that.

2. Add a tag_debug block before the PFB clock_sync and look for time_est
tags with values outside the range [0.0, 1.0).

-Andy