__debugbreak enable/disable

sx, sxd, sxe, sxi, sxn, sxr, sx- (Set Exceptions)

The sx* commands control the action that the debugger takes when an exception occurs in the application that is being debugged, or when certain events occur.

Remarks

The sx command displays the list of exceptions for the current process and the list of all nonexception events and displays the default behavior of the debugger for each exception and event.

The sxe, sxd, sxn, and sxi commands control the debugger settings for each exception and event.

The sxr command resets all of the exception and event filter states to the default settings. Commands are cleared, break and continue options are reset to their default settings, and so on.

The sx- command does not change the handling status or the break status of the specified exception or event. This command can be used if you wish to change the first-chance command or second-chance command associated with a specific event, but do not wish to change anything else.

If you include the -h option (or if the cc, hc, bpec, or ssec events are specified), the sxe, sxd, sxn, and sxi commands control the handling status of the exception or event. In all other cases, these commands control the break status of the exception or event.

When you are setting the break status, these commands have the following effects.

Command	Status name	Description
sxe	Break (Enabled)	When this exception occurs, the target immediately breaks into the debugger before any other error handlers are activated. This kind of handling is called first chance handling.
sxd	Second chance break (Disabled)	The debugger does not break for a first-chance exception of this type (although a message is displayed). If other error handlers do not address this exception, execution stops and the target breaks into the debugger. This kind of handling is called second chance handling.
sxn	Output (Notify)	When this exception occurs, the target application does not break into the debugger at all. However, a message is displayed that notifies the user of this exception.
sxi	Ignore	When this exception occurs, the target application does not break into the debugger at all, and no message is displayed.

 

When you are setting the handling status, these commands have the following effects:

Command	Status name	Description
sxe	Handled	The event is considered handled when execution resumes.
sxd,sxn,sxi	Not Handled	The event is considered not handled when execution resumes.

 

You can use the -h option together with exceptions, not events. Using this option with ch, bpe, or sse sets the handling status for hc, bpec, or ssec, respectively. If you use the -h option with any other event, it has no effect.

Using the -c or -c2 options with hc, bpec, or ssec associates the specified commands with ch, bpe, or sse, respectively.

In the following example, the sxe command is used to set the break status of access violation events to break on the first chance, and to set the first-chance command that will be executed at that point to r eax. Then the sx- command is used to alter the first-chance command to r ebx, without changing the handling status. Finally, a portion of the sx output is shown, indicating the current settings for access violation events:

0:000> sxe -c "r eax" av 0:000> sx- -c "r ebx" av 0:000> sx av - Access violation - break - not handled Command: "r ebx" . . .

disable : sxi bpe

enable : sxi bpe

http://stackoverflow.com/questions/9099586/how-can-i-remove-breakpoint-ntdlldbgbreakpoint0x1-in-windbg