KDB+KMS for nouveau/radeon —
First, some background: KDB (a kernel debugger shell) and KMS (kernel mode-setting) combine to let you drop into a graphical shell when something debugger-worthy happens on your Linux machine. That thing might be a panic, or a breakpoint, or a hardware trap, or a manual entry into the kdb shell. Inside the shell you can, for example: get a backtrace, inspect
ps, look at memory contents, and kill tasks.
This is a big improvement over the previous model of “something bad happens to your laptop while it’s in X, and the keyboard LEDs start blinking, and you hard-reboot and wonder what happened and wish your laptop had a serial port”.
Here’s a video of KDB+KMS in action — it’s from Jason Wessel at Wind River, who deserves massive kudos for having enough patience to get all of this debugging code merged into mainline Linux to everyone’s satisfaction:
Jesse recently wrote about how to give KDB+KMS a spin on Intel graphics chipsets, and now I’ve written patches that allow radeon and nouveau users to join in too. The method for testing them is similar to Jesse’s:
git clone git://dev.laptop.org/users/cjb/linux-2.6
git checkout kgdb-next
- Config the kernel as in Jesse’s post, and build/install it.
- Boot with
- Enter KDB with sysrq-g, or
echo g > /proc/sysrq-trigger, and type
goto leave KDB.
If you test with radeon or nouveau, please let me know what hardware you tested on, and whether everything worked. Thanks!