Re: [RFC PATCH] x86 single-step (TF) vs system calls & traps

[Linus Torvalds]

On Mon, 28 Jun 2004, Roland McGrath wrote:
> 
> When you single-step into a trap instruction, you actually don't get a
> SIGTRAP until the instruction after the trap instruction has also executed.

Yes. This is documented Intel behaviour. It also guarantees that there is 
forward progress in some strange circumstances, if I remember correctly.

And I refuse to make the fast-path slower just because of this. Not only 
has Linux always worked like this, as far as I know all other x86 OS's 
also tend to just do the Intel behaviour thing.

		Linus
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