Re: ntdll: Fix SIGTRAP handling

[Alexandre Julliard]

Petr Tesarik  writes:
> - The x86 spec states that a single-step interrupt (INT 1) is
> generated if the TF bit was set when the execution of the
> instruction BEGAN.  This means that if the instruction changes the
> TF bit (e.g. popf), there is an INT 1, but the TF bit is not set
> any more.  The only way to check whether the interrupt was
> generated because of the TF bit, is to check bit 15 in DR6.

I don't see why you can't still check the TF bit, it will be set 99%
of the time, and fetching the DR6 register is quite expensive.
> The following patch fixes all of these issues.

I'd really like to see test cases showing that Windows does things
this way.