How to turn off Windows kernel debugging at boot time?
I have a Vista 32 bit machine which I wanted to enable local kernel debugging on. In WinDbg I selected File/Kernel Debug and selected the Local tab and clicked ok. I got the following message.
The system does not support local kernel debugging. ... Local kernel debugging is disabled by default in Windows Vista, you must run 'bcdedit -debug on' and reboot to enable it.
I naively followed the instructions and opened an elevated command prompt and typed 'bcdedit -debug on' and the rebooted.
However, on reboot the system hangs when it gets to the logon screen - or just after I type in my username and password.
I suspect what is happening is that because a debugger is enabled, user mode exceptions are being triggered in the kernel debugger process and it is waiting for me to enter some input from an attached debugger??
I was hoping to debug on the actual target machine.
My problem is that every time I boot - whatever F8 boot option I choose - it always either hangs or gets so far and then reboots - and then hangs.
Booting in Safe Mode - gets close to the logon screen and then reboots. Same applies for the command line and network boot options. Last known good config - hangs too.
Is there any way to change the boot option before Windows loads so that I can turn off kernel debugging. I have only the one boot config which was, in hindsight, my problem - I should have created a copy of the first boot config for my debug boot option.
Unfortunately the system doesn't have a serial port so I can't attempt to debug through that.
The only option I can think of now is to attempt to connect a debugger from a different machine through a USB port. However, don't I need to configure the target PC to accept a debugger on a USB port or will this just work if I get a proper debug USB cable?
Answer
There is no need for to use the repair option! Just press F10 instead of F8, now you will be able to edit the bootparameter! Just delete /DEBUG and press enter to continue the boot process. After set use bcdedit -debug off to permanently change the debug option.