Getting Started with gdbserver
Introduction
This documentation shows how to get started with gdbserver with a basic application. When using gdb binaries need to be compiled with debug symbols.
Application and target should have networking. For more information about SDK please check
developer.ridgerun.com/wiki/index.php/RidgeRun_Turrialba_SDK_User_Guide
Compilation process
CFLAG -ggdb:
The ggdb flag produces debugging information specifically intended for gdb, it is recommended to use this flag when using gdb for debuggin
- -ggdb (same as ggdb2)
- -ggdb1
- -ggdb2
- -ggdb3
Example:
AUTOTOOLS_PARAMS = LDFLAGS="-Wl,--rpath-link -Wl,$(FSDEVROOT)/usr/lib:$(FSDEVROOT)/lib" --sysconfdir=$(FSDEVROOT)/etc CFLAGS="-ggdb3"
CFLAG -g
The -g flag can also be added In order to add debug symbols, autotools parameters need to specify cflags as CFLAGS="-g -O0". This flag can be also added at libraries and other utilities, for example gstreamer plugins.
AUTOTOOLS_PARAMS = LDFLAGS="-Wl,--rpath-link -Wl,$(FSDEVROOT)/usr/lib:$(FSDEVROOT)/lib" --sysconfdir=$(FSDEVROOT)/etc CFLAGS="-g -O0"
Selecting gdb server on target file system
Select gdb server on File System Configuration:
[*] Install GDB server on target file system
Compile SDK and install on target.
Executing gdb
Running application with gdbserver on target
Execute application with gdbserver:
gdbserver <HOST_IP>:<PORT> <APPLICATION_BINARY>
This will leave the application waiting for the host, current output:
/ # gdbserver 10.251.101.11:2345 hello_gdb Process hello_gdb created; pid = 1179 Listening on port 2345
Running gdb on Host
gdb needs to be for arm compiler, codesourcery distributes their toolchain with the binary, usually located at: codesourcery/arm-2009q1/bin/arm-none-linux-gnueabi-gdbtui.
Execute gdbtui binary:
arm-none-linux-gnueabi-gdbtui
At debugger command line some commands needs to be executed in order to start the application remotely:
Specify path to system root:
set solib-absolute-prefix $(DEVDIR)/fs/fs
Specify binary to work with (usually the binary is inside of root file system specified before)
file <PATH_TO_BINARY>
This will load the binary and will display debug information (Current output of gdbtui):
┌──hello_gdb.c─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│38 { │
│39 int i; │
│40 │
│41 /* Mandatory "Hello, world!" */ │
│42 │
│43 deb_puts("Getting ready to say \"Hello, world\"\n"); │
│44 printf("Hello, world!\n"); │
│45 deb_puts("It has been said.\n"); │
│46 │
│47 /* Print arguments */ │
│48 │
│49 printf("argc\t= %d\n", argc); │
│50 printf("argv\t= 0x%p\n", argv); │
│51 │
│52 for (i = 0; i < argc; i++) │
│53 { │
│54 printf("argv[%d]\t= ", i); │
│55 if (argv[i]) │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
exec No process In: Line: ?? PC: 0x0
(gdb) cd
Argument required (new working directory).
(gdb) cd /home/USER/devdirs/DEVDIR/fs/fs
Working directory /home/USER/devdirs/DEVDIR/fs/fs.
(gdb) set
Argument required (expression to compute).
(gdb) set solib-absolute-prefix .
(gdb) file usr/bin/hello_gdb
Reading symbols from /home/USER/devdirs/DEVDIR/fs/fs/usr/bin/hello_gdb...done.
(gdb)
Set breakpoints:
Use the following command:
break <LINE_NUMBER>
This will specify an integer number at the breakpoint.Also the C file name may be specified if using various C files:
break <C_FILE.c>:<LINE_NUMBER>
Example of breakpoint being applied at line 45:
┌──hello_gdb.c─────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│38 { │
│39 int i; │
│40 │
│41 /* Mandatory "Hello, world!" */ │
│42 │
│43 deb_puts("Getting ready to say \"Hello, world\"\n"); │
│44 printf("Hello, world!\n"); │
b+ │45 deb_puts("It has been said.\n"); │
│46 │
│47 /* Print arguments */ │
│48 │
│49 printf("argc\t= %d\n", argc); │
│50 printf("argv\t= 0x%p\n", argv); │
│51 │
│52 for (i = 0; i < argc; i++) │
│53 { │
│54 printf("argv[%d]\t= ", i); │
│55 if (argv[i]) │
└──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘
exec No process In: Line: ?? PC: 0x0
Undefined command: "ls". Try "help".
(gdb) pwd
Working directory /home/USER/devdirs/DEVDIR.
(gdb) file myapps/hello-gdb/src/src/hello_gdb
Reading symbols from /home/USER/devdirs/DEVDIR/myapps/hello-gdb/src/src/hello_gdb...done.
(gdb) berak 45
Undefined command: "berak". Try "help".
(gdb) break 45
Breakpoint 1 at 0x8478: file hello_gdb.c, line 45.
(gdb)
Delete break point
Use the delete command and breakpoint number
delete 2
Specify remote application
Specify target remote application:
target remote <BOARD _IP_ADDRESS>:<PORT>
Run binary
To run the binary use the continue, application will stop at breakpoints
continue
Output when gdb encounters a breakpoint
Breakpoint 1, main (argc=1, argv=0xbeae2ea4, envp=0xbeae2eac) at hello_gdb.c:49 (gdb)
Using ddd with gdb
In order to use ddd with arm gdb run ddd and specify the arm gdb:
ddd --debugger /opt/codesourcery/arm-2009q1/bin/arm-none-linux-gnueabi-gdb
ddd has a command line at the GUI, use the same commands as when using gdbtui. In order to run the binary use the exact same command: "continue"
breakpoints can be added and removed manually at the GUI, the break command also works for this.