[Qemu-devel] Re: Something is probably wrong with "int 3"

["Alexander E. Patrakov" <patrakov@ums.usu.ru>]

Alexander E. Patrakov wrote:

> Johannes Schindelin wrote:
> 
>> Hi,
>> 
>> On Tue, 4 Jan 2005, Alexander E. Patrakov wrote:
>> 
>>> Andr? Braga wrote:
>>>
>>> > On Tue, 04 Jan 2005 18:09:32 +0500, Alexander E. Patrakov
>>> > <patrakov@ums.usu.ru> wrote:
>>> >> clearly state that the fault is at the "int 3" instruction, not at
>>> >> "ret". Can anyone explain this difference? Is this a bug in qemu?
>> 
>> That is quite normal. As int 3 is already executed when the pop up is
>> triggered, the program counter in that frame points to the next insn.
> 
> I will nevertheless check that by means of writing and executing a test
> program.

Well, I am totally confused. The test program is:

#include <windows.h>

int APIENTRY WinMain(HINSTANCE p1, HINSTANCE p2, LPSTR p3, int p4)
{
        DebugBreak();
        return 0;
}

As expected, this crashes, and the fault is at "int 3" in qemu. So it looks
like no bug is here. But then, why does Firefox produce a visible fault at
"ret", not at "int 3"? Maybe there's some exception handler that handles
the first exception on "int 3" and then the second, unhandled, exception is
produced on "ret"?

-- 
Alexander E. Patrakov