Linux debugging with Jtag - [ARM9][AT91SAM9G25] - Amontec, openocd, gdb, eclipse

Question

I'm trying to start kernel debugging with this sytem: Amontec JTAGkey2, openocd, gdb, eclipse.

At the end I would like to debug kernel and application that is running within. I have few problems, and it seems that I need to solve them sequently. Now I have CPU suspend/resume, read/write RAM What is missing: Step into, Step over, C/C++ Level debugging.

I do following: - Connect JTAG, Power up board, start uImage with Debug messages via Uboot - start openocd:

# openocd -f /usr/share/openocd/scripts/interface/jtagkey2.cfg -f /usr/share/openocd/scripts/board/at91sam9g20-ek.cfg

Output:

jtag_nsrst_delay: 200
jtag_ntrst_delay: 200
RCLK - adaptive
     TapName            | Enabled |   IdCode      Expected    IrLen IrCap  IrMask Instr     
---|--------------------|---------|------------|------------|------|------|------|---------
 0 | at91sam9g20.cpu    |    Y    | 0x00000000 | 0x0792603f | 0x04 | 0x01 | 0x0f | 0x0f
Info : max TCK change to: 30000 kHz
Info : RCLK (adaptive clock speed)
Info : JTAG tap: at91sam9g20.cpu tap/device found: 0x0792603f (mfg: 0x01f, part: 0x7926, ver: 0x0)
Info : Embedded ICE version 6

And problems starts here:

openocd:

Warn : acknowledgment received, but no packet pending
undefined debug reason 6 - target needs reset
Warn : target not halted

eclipse:

symbol-file /opt/Tixi_Repos/KiwiG6v2/buildroot-2011.05/package_tixi/linux-2.6.39/arch/arm/boot/compressed/vmlinux
target remote localhost:3333
start () at arch/arm/boot/compressed/head.S:108
108 kphex r5, 8 /* end of kernel */

It seems also that JTAG is trying to load the code into 0x0, what is incorrect I suppose:

Update 1:

After analyzing some online tutorials for ARM:

Eclipse Reset and Halt commands doesn't work perfect. It is better to uncheck them and write into command window. Also load address can be add:

monitor halt
load arch/arm/boot/compressed/vmlinux 0x22000000

I don't use

monitor reset

I let Uboot start and initialize RAM and other peripherals. Then I stop Uboot by getting into shell. Then I let eclipse write linux into RAM, and start it. It takes very long, but works bit better. Kernel starts and stopps on RPC initialization without giving console back.

• would it be possible to load kernel into RAM within Uboot console, and start JTAG session afterwards ?
• What is the difference between [load ...] and [monitor load...] commands
• Why do I need to load /compressed/vmlinux instead of uImage ?
• in eclipse window I have two load fields: load image i load symbol. I disable both options but write only load arch/arm/boot/compressed/vmlinux 0x22000000. Is it maybe the reason for next problems ?

Update 2: Ok. Thank you for hints.

I've made some progress. Could you give me some advices, maybe I'm still doing something wrong.

Now my kernel runs under JTAG control, but I still can't debug on source code level.

I do as follows:

1. Power up the board, go into uboot shell.
2. start openOCD session

3. Set Uboot breakpoint in bootm.c on theKernel call:

   cleanup_before_linux ();
   theKernel (0, machid, bd->bi_boot_params);
   

4. start eclipse debug session :

   • monitor halt

   • load uboot-a without offset

     load u-boot-2010.06/u-boot 
     Loading section .text, size 0x349ec lma 0x26f00000
     

   • start uboot and let it run

   • uboot stopps on "theKernel" call

I know that kernel is located on address 0x20008000.

5. restart openOCD session

6. start ecipse debugger once more with kernel configuration:

   • monitor halt

   • load kernel on address 0x20008000

     load arch/arm/boot/compressed/vmlinux 0x20008000
     Loading section .text, size 0x8bdc7c lma 0x20008000
     

   • start debugg session

Everything works fine now, and kernel starts, but I still can't debug on source code level.

"symbol is not available" DEBUG and DEBUG_INFO are on for kernel.

vmlinux screenshot

What seems starnge for me that there are around 50 function symbols in this file.