Linux kernel debugging on ARM9 LPC3250

Hello,

I’m trying to debug Linux kernel using KGDB:

  • kernel was built with debugging symbols support, KGDB support, serial port driver support etc

  • laptop running Debian GNU/Linux connected with Serial-To-Usb cable (/dev/ttyUSB0 at laptop, /dev/ttyS0 at the board)

  • kernel boot args: console=ttyS0,115200n81 root=/dev/nfs rw nfsroot=192.168.0.7:/home/raydan/ltib/rootfs ip=192.168.0.10 init=/sbin/init kgdboc=ttyS0,115200

In minicom session after shell prompt I enter ‘Ctrl+Alt+F+G’ and get:

SysRq : GDB

Entering KGDB

Then on the laptop I execute ‘gdb vmlinux’, then in gdb ‘set remotebaud 115200’ and ‘target remote /dev/ttyUSB0’. Output is:

Remote debugging using /dev/ttyUSB0

0x00000007 in start () at arch/arm/boot/compressed/head.S:101

101 #ifdef DEBUG

Current language: auto; currently asm

Looks like debugging initializes fine, but when I execute ‘next’ gdb command to step over kernel, gdb prints:

warning: Invalid remote reply:

Then board console prints nothing, laptop gdb just hangs.

Could anybody help with this trouble?

Best Regards,

Dmitry Vinokurov