KGDBoE - a kernel module that allows debugging the Linux kernel using the network connection. It is useful on modern PCs that don't have a serial port or a JTAG connector and it's much faster than using a COM port.

KGDBoE is inspired by the original kgdboe patches by Jason Wessel, but goes well beyond the capabilities of the original tool. The key features are:

• Works with stock kernels without rebuilding them. Tested on Linux Kernel 3.8.0-4.1.0.
• Easy configuration. No need to specify the IP or MAC addresses.
• Supports modern multi-core systems.
• Works with pcnet32, r8169 and e1000 network drivers.

git clone https://github.com/dzeromsk/kgdboe.git
cd kgdboe
make -C /lib/modules/$(uname -r)/build M=$(pwd)

sudo insmod kgdboe.ko device_name=eth0
dmesg | tail

gdb /boot/vmlinuz
target remote udp:<IP>:31337

Find out module address

sudo grep modulename /proc/modules
modulename 1073152 5 - Live 0xffffffffa0120000

In the gdb (remote)

add-symbol-file drivers/char/modulename.ko 0xffffffffa0120000

• device_name=eth0 -- Ethernet device to use for debugging.
• local_ip -- Local IP address to bind to. Auto-detected if not specified.
• udp_port=31337 -- UDP port to use for debugging.
• force_single_core=1 -- Disable all cores except #0 when the module is loaded. This setting is recommended unless you are debugging SMP-specific issues, as it avoids many synchronization problems. KGDBoE can reliably work in the SMP mode, but it has not been tested on all network drivers, so use caution if you decide to disable this.

KGDBoE uses some of the network stack code to communicate to your gdb. Setting breakpoints in the code that is used by it would deadlock your debugging session. Follow the tips below to avoid it:

• Don't set breakpoints in the network code
• Don't set breakpoints in mod_timer() unless you're using the single-CPU mode
• Use the single-CPU mode unless you absolutely need SMP. Although KGDBoE includes workarounds for multi-CPU mode, they are based on making assumptions about the network driver internals and can be safely avoided by disabling all CPUs except #0 during debugging.

The source code is available under the GPL license.

Source: http://sysprogs.com/VisualKernel/kgdboe/