Re: [Xen-devel] [Fwd: stack overflow "cause" found]

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 26 Jul 2006, at 22:49, Rik van Riel wrote:

> > > > Xen really should not be doing this.  We could either uninline some 
> > > > of
> > > > these functions, or try gcc -O2 or gcc -Os.
> > > OK, with -Os it doesn't quite build due to the built-ins not being
> > > inlined.  With -O2 the stack usage changes dramatically...
> > It would be nice if -O2 worked. Quite a scary change give the amount 
> > of inline asm  though...
> Not only does -O2 seem to work, but without it we get stack
> overflows and things suddenly stop working.
>
> I've been beating up my x86-64 system with a few VT and paravirt
> guests for over an hour now, and it no longer crashes.  Without
> -O2, I can make it crash within minutes...
We only avoided -O2 on debug builds. It's trivial to add it back in. 
Seems gcc is just really dumb with anything less. I'll add it back in 
for debug builds. I also made the stack space larger, so we'll be 
double-protected from overflows in future. :-)
 -- Keir


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