Re: what exactly is a "segmentation fault"

[rich <rehartma@artsci.wustl.edu>]

>> When I tried to run the program (by typing multitrack), I get a
>> "segmentation fault" error... I have heard this phrase before, but do
>> not know what it means... can anyone help, or at least point me in the
>> right direction?
 

>A segmentation fault means that the program made an illegal memory
>access.  This can be done in many ways and it is now always the
>author's fault, it could be a library problem.

>First, run ldd /path/to/my program

>Every item in the list should have a left and right side.



Here is what that tells me - it seems like everything is okay?

        libvga.so.1 => /usr/lib/libvga.so.1 (0x4000c000)
        libvgagl.so.1 => /usr/lib/libvgagl.so.1 (0x40058000)
        libX11.so.6 => /usr/lib/libc5-compat/libX11.so.6 (0x40067000)
        libm.so.5 => /lib/libm.so.5 (0x40105000)
        libc.so.5 => /lib/libc.so.5 (0x4010e000)
        libc.so.6 => /lib/libc.so.6 (0x401cc000)
        libm.so.6 => /lib/libm.so.6 (0x40271000)
        ld-linux.so.2 => /lib/ld-linux.so.2 (0x4028a000)



>Next, run strace -o output program.  At the bottom of the file called
>output you will see some cryptic function calls.  They may offer a
>clue.


... bunch of stuff followed by...
geteuid()                               = 0
getuid()                                = 0
getgid()                                = 0
getegid()                               = 0
getpid()                                = 1201
--- SIGSEGV (Segmentation fault) ---
+++ killed by SIGSEGV +++

Does this tell me anything?

This also seems similar to an error that I get when I try to run
"emusic" - nothing happens until I  ^C, then I get the next message...

Gdk-Message: 
** ERROR **: sigint caught

All other sound stuff seems to work...

Any clues?

also....

>Another thing that caused multitrack to "segfault" me was a setting in the
>preferences file  ~/.multitrack/prefs

>I changed this to read:

>#=========================================================
># Audio buffers section
>#=========================================================
>
>o_nr_buffers = 10
>i_nr_buffers = 10


I don't have this file - I guess because the program hasn't fully run
yet?


Thanks,

Rich