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I'm trying to use GDB to debug (to find an annoying segfault). When I run:
gdb ./filename
from the command line, I get the following error:
This GDB was configured as "i686-pc-linux-
gnu"..."/path/exec": not in executable
format: File format not recognized
When I execute:
file /path/executable/
I get the following info:
ELF 64-bit LSB executable, AMD x86-64,
version 1 (SYSV), for GNU/Linux 2.4.0,
dynamically linked (uses shared libs), not stripped
I am using GDB 6.1, and the executable is compiled with gcc version 3.4.6.
I'm a little out of my water in terms of using gdb, but as far as I can tell it should be working in this instance. Any ideas what's going wrong?
946
An ELF file consists of zero or more segments, and describe how to create a process/memory image for runtime execution. When the kernel sees these segments, it uses them to map them into virtual address space, using the mmap(2) system call. In other words, it converts predefined instructions into a memory image.
gcc produces executable files in the ELF file format. you can use readelf and objdump to read parts of an elf file. You can also use 'hexdump filename' to get a hexdump of the contents of a binary file (this is likely only useful if you like reading machine code or you are writing an assembler).
An ELF file is an executable file format for the Linux and Unix platforms. Its known file extensions are . axf, . bin, .
Whenever we compile any code, the output that we get is an executable file, which we generally don't bother about. We execute it on our desired target. If it is an embedded system, we flash it to the target device and run it. Usually, this executable file is the ELF (Executable and Linkable Format) file.
The executable is 64-bit (x86-64) and the debugger is a 32 bit (i686-pc-linux) build. You may need to install a 64-bit (x86-64) version of the debugger.
122
I'm not sure if this is your problem, but I faced this situation very often. The executable in the build tree, build by make/automake is not a binary, but a script, so you cannot use gdb with it. Try to install the application and change the directory, because else gdb tries to debug the script.
5
The question refers to "./filename" and to "/path/executable". Are these the same file?
If you are doing a post-mortem analysis, you would run:
gdb executable-file core-file
If you are going to ignore the core file, you would run:
gdb executable-file
In both cases, 'executable-file' means a pathname to the binary you want to debug. Most usually, that is actually a simple filename in the current directory, since you have the source code from your debug build there.
On Solaris, a 64-bit build of GDB is supposed to be able to debug both 32-bit and 64-bit executables (though I've had some issues with recent versions of GDB). I'm not sure of the converse - that a 32-bit GDB can necessarily debug 64-bit executables.
4
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