Re: Sysenter crash with Nested Task Bit set

[Ingo Molnar <mingo@elte.hu>]

* Andi Kleen <ak@suse.de> wrote:

> >  #define switch_to(prev,next,last) do {					\
> >  	unsigned long esi,edi;						\
> > -	asm volatile("pushl %%ebp\n\t"					\
> > +	asm volatile("pushfl\n\t"		/* Save flags */	\
> > +		     "pushl %%ebp\n\t"					\
> 
> We used to do that pushfl/popfl some time ago, but Ben removed it 
> because it was slow on P4.  Ok, nobody thought of that case back then.

I _should_ have thought of that though, because when this change was 
done originally i had to reintroduce it both for exec-shield and for 
-rt, so apparently it must have triggered in certain circumstances - i 
just didnt notice the reason. (but recent exec-shield and -rt patches 
dont have this revert, so the condition must have gone away. But it was 
a long time ago.)

	Ingo