Debugging a laptop with no serial port

I have a HP Pavilion G6 laptop that I’m trying to debug a system crash while running the Haiku build system within Haiku B1. It’s a dead lock up, complete screen and UI freeze. No kdl screen comes up on this particular crash. The only way to recover is a hard reset. So no logging is saved upon reboot that can be recovered via the boot manager. Is there any way of gleaning any usable debugging info in this sort of situation? Kdl functions normally when called with the hot key and also in other crashes on this machine.

Well, if you get access to KDL you can investigate there. Start by looking at what the CPUs are doing. Check the “ints” command for problems with interrupts (are they the one locking the CPUs?), check the running threads (are CPUs idling, or arethey busy?), etc.

Also, are you sure the complete system is frozen, or is it just app_server? In some cases (eg. when all ports for IPC are used) the app_server will crash, but the debugger will also fail to start, and this looks pretty much like a hard lockup, but eg. keyboard leds and ssh would continue to function normally. Maybe that’s the first thing to check, as if you have ssh, it may be easier to investigate things from userland.

Well, ssh may be my last bet. The lock ups are complete UI freeze. I can’t use the keyboard to call kdl. Not once has kdl come up on this lock.