Re: Octave 4.0.0-3 x86_64 segfault (suspect openblas)

[Marco Atzeri <marco.atzeri@gmail.com>]

On 23/11/2015 04:33, Tony Kelman wrote:
> The following works fine on 32 bit, but segfaults reliably on 64 bit:
>
> $ octave
[cut]
>
> octave:1> D = 1000*(rand(1000,1000)-0.5);
> octave:2> [E,F] = eig(D)
> panic: Segmentation fault -- stopping myself...
> attempting to save variables to 'octave-workspace'...
> save to 'octave-workspace' complete
> Segmentation fault (core dumped)

likely openblas or its iteration with lapack

To test without openblas , you can renable netlib blas
$ mv /usr/bin/cygblas-0.dll  /usr/bin/cygblas-0.dll_bk


> I see the same when I call a mingw-w64 build of openblas 0.2.15 through
> Julia (which isn't packaged in Cygwin but shares many common
> dependencies with Octave), so this is mostly to let Marco know about the
> issue. I'll have to reduce this to the corresponding Lapack call and
> come up with a standalone C or Fortran test case to report upstream. My
> processor is a Sandy Bridge i7-2630QM.
>
> -Tony
>

Same with i5-3320M
The bug seems not present in openblas 0.2.14

As latest octave and openblas now have a debuginfo package:

Program received signal SIGSEGV, Segmentation fault.
0x00000003c866ad50 in cygblas-0!blas_memory_free () from 
/usr/bin/cygblas-0.dll
(gdb) bt
#0  0x00000003c866ad50 in cygblas-0!blas_memory_free () from 
/usr/bin/cygblas-0.dll
#1  0x00000003c841eff8 in dgemv_ () from /usr/bin/cygblas-0.dll
#2  0x00000003aa785fae in dlahr2_ () from /usr/lib/lapack/cyglapack-0.dll
#3  0x00000003aa73f8ec in dgehrd_ () from /usr/lib/lapack/cyglapack-0.dll
#4  0x00000003aa73c1f3 in dgeev_ () from /usr/lib/lapack/cyglapack-0.dll


Regards
Marco

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple