output message not clear when debuging using gdb with core file

Question

I am debugging my c code using gdb on ubuntu 12.04 and below is the command for that:

msz@ubuntu:~$ gdb m core

After running the above command, i get following message:

warning: Can't read pathname for load map: Input/output error.

warning: no loadable sections found in added symbol-file system-supplied DSO at 0x7fff8cdfe000
Core was generated by `./m'.
Program terminated with signal 11, Segmentation fault.
#0  0x0000000000400962 in matmultunopt ()

What are the meanings of these two warnings? what can be concluded from the last line i.e

#0  0x0000000000400962 in matmultunopt ()

Of course it gives some hint that there is a some issue in matmultunopt (), but what is :

#0  0x0000000000400962

and what are the warning actually telling me ?

UPADTE

Now i did this using -g and got the following message:

warning: Can't read pathname for load map: Input/output error.

warning: no loadable sections found in added symbol-file system-supplied DSO at 0x7fffde2c8000
Core was generated by `./m'.
Program terminated with signal 11, Segmentation fault.
#0  0x0000000000400962 in matmultunopt (matrix1=0x3, matrix2=0xd7d030, 
    resultant=0xd7d050, rows1=2, colmns1=2, rows2=2, colmns2=2)
    at mattmgpuf1.c:115
115         {   double a = matrix1[i*rows2 + k];

Still, I am unable to understand the meaning of the given line:

 #0  0x0000000000400962 in matmultunopt (matrix1=0x3, matrix2=0xd7d030, 
        resultant=0xd7d050, rows1=2, colmns1=2, rows2=2, colmns2=2)

Did you compile m with symbols? (option -g to gcc) Had there been enough diskspace to write the full core. What does ulimit -a tell you about the maximum core size? — alk
– alk, Commented Jan 8, 2014 at 7:50
Does the build of m match the build which created the core. Or did you recompile m after the core had been created by a previous version of m. — alk
– alk, Commented Jan 8, 2014 at 7:56

alk · Accepted Answer · 2014-01-08 17:09:46Z

2

The debugger's output explained:

#0  0x0000000000400962 in matmultunopt (matrix1=0x3, matrix2=0xd7d030, resultant=0xd7d050, rows1=2, colmns1=2, rows2=2, colmns2=2) at mattmgpuf1.c:115
^^  ^----------------^    ^----------^  ^---------------------------------------------------------------------------------------^     ^--------------^
|   |                     |             |                                                                                             |
|   |                     |             |                                                                                             +-- source file name and line where the program stopped
|   |                     |             +-- current function's parameters and their values
|   |                     +-- current function
|   +-- program address
+-- stack/call level

answered Jan 8, 2014 at 17:09

alk

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