[OpenWrt-Devel] Debugging OpenWRT ELF image with GDB on host system

[Madhavi Manchala]

Dear All,

We are unable to debug the OpenWRT image through GDB from a host
system. When we try to debug, we are seeing the following error
messages on the GDB screen. We are running the GDB from Cygwin on a
Windows XP system.

No symbol table is loaded. Use the "file" command.
Make breakpoint pending on future shared library load?

We also tried to load the executable image from <gdb> prompt with
"file" command. This time, we are seeing the following error messages.
<no debugging symbols found> ...done.

We enabled the following from "make menuconfig" which we run from the trunk.

Advanced configuration options (for developers) [enter] → Toolchain
Options → [*] Build gdb
Utilities → gdbserver

Shall we need to be changed CFLAGS in any Makefile for including the -g option?

Any suggestions / ideas / links would be appreciated and help us a lot.

Thanks and Regards,
Madhavi M.

[Sławomir Cygan]

Hi,

Post by Madhavi Manchala
We are unable to debug the OpenWRT image through GDB from a host
system. When we try to debug, we are seeing the following error
messages on the GDB screen. We are running the GDB from Cygwin on a
Windows XP system.

Please use cross-compiled version of gdb - the one build by OpenWRT.

Post by Madhavi Manchala
Shall we need to be changed CFLAGS in any Makefile for including the -g option?

Propably, or modify global CFLAGS setting in OpenWRT. By default all
programs are build without debug info (and can be stripped, but I am
not sure about this at the moment).

Post by Madhavi Manchala
Any suggestions / ideas / links would be appreciated and help us a lot

My own point of view: usually it is better to use printf() instead of
gdb and printk() instead of kgdb.

[Madhavi Manchala]

Dear Slawomir Cygan,

Thank you very much for your infromation.

Post by Sławomir Cygan
Hi,

Post by Madhavi Manchala
We are unable to debug the OpenWRT image through GDB from a host
system. When we try to debug, we are seeing the following error
messages on the GDB screen. We are running the GDB from Cygwin on a
Windows XP system.

Please use cross-compiled version of gdb - the one build by OpenWRT.

I am trying to debug the vmlinux OpenWRT image which is build for my
target device. The procedure that I am following is as follows.

I build the OpenWRT image (vmlinux) on a Linux box in the ELF format
for my Samsung MCU. Then, I am trying to load it on to my device's RAM
area using a J-Link J-TAG and J-LinkGDBServer tool with a .gdbinit
script from a Windows XP system. The .gdbinit script contains the
initialization of the address map and CPU registers UART etc. Then, I
am running the gdb from Cygwin on Windows XP system. If this is the
case, how can I use OpenWRT gdb? Where is OpenWRT gdb available? Is
it in staging_dir?

Post by Sławomir Cygan

Post by Madhavi Manchala
Shall we need to be changed CFLAGS in any Makefile for including the -g option?

Propably, or modify global CFLAGS setting in OpenWRT. By default all
programs are build without debug info (and can be stripped, but I am
not sure about this at the moment).

Yes. By default all are build without debugging information. I added
-g option in the Makefile which is located at the
trunk/target/linux/board directory.

Post by Sławomir Cygan

Post by Madhavi Manchala
Any suggestions / ideas / links would be appreciated and help us a lot

My own point of view: usually it is better to use printf() instead of
gdb and printk() instead of kgdb.

I am not able to see any debug messages on the hyper terminal. That is
the reason, I want to put some break points in the HAL code and need
to check whether it is reaching there or not through gdb. I explained
the loading procedure above.

Please let me know, if you need any additional information. I will provide.

Thanks and Regards,
Madhavi M.

Post by Sławomir Cygan
--
Pozdrawiam,
Sławomir Cygan
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[Sławomir Cygan]

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[Madhavi Manchala]

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