Re: [Jack-Devel] Stack preallocation issues

On Tue, Mar 15, 2011 at 01:57:41PM +0200, Sampo Savolainen wrote:

> Would doing this be unsafe?
> 
> static void
> jack_thread_touch_stack()
> {
>  char foo;
>  memset(&foo, 0, JACK_THREAD_STACK_TOUCH);
> }

It would probably overwrite memset's return address,
stack frame and internal variables.

It could actually work on systems that keep the return
address in a register and implement memset() using only
registers and without its own stack frame (this would
be possible on an ARM for example).

Regarding the compiler optimising away the whole stack
touching code, it clearly shouldn't do this if it assumes
the code can have side effects, i.e. if the array is
declared volatile.


Ciao,

-- 
FA

1300195408.12983_0.ltw:2,a <20110315132314.GA17058 at linuxaudio dot org>