Re: [PATCH] hw/net: move allocation to the heap due to very large stack frame

[Elena Afanasova]

On Tue, 2020-10-13 at 16:32 +1100, David Gibson wrote:
> On Mon, Oct 12, 2020 at 03:45:02PM +0200, Paolo Bonzini wrote:
> > On 12/10/20 12:44, Thomas Huth wrote:
> > > I think this is one of the tasks from:
> > > 
> > >  
> > > https://wiki.qemu.org/Contribute/BiteSizedTasks#Compiler-driven_cleanups
> > > 
> > > It has been added by Paolo in 2016:
> > > 
> > >  
> > > https://wiki.qemu.org/index.php?title=Contribute/BiteSizedTasks&diff=5368&oldid=5367
> > > 
> > > ... so maybe Paolo can comment on the size that has been chosen
> > > here...?
> > 
> > I used 16K, mostly because it is a nice round number.  8k is too
> > small
> > due to PATH_MAX-sized variables.  16k seemed to be plenty and
> > triggered
> > in few-enough places that the cleanup is viable.
> 
> Ok.  Why are large stack frames bad in qemu?
> 

I think that the main issue here is alloca() because it can lead to UB.