On Fri, 29 Sep 2006, Jason Thorpe wrote:

> > Log Message:
> > Add -mapcs-frame -fno-omit-frame-pointer to acorn26 kernel builds.  This
> > is necessary to ensure that GCC saves R14_svc on entry to every function,
> > and thus that page faults within the kernel are safe (since they corrupt
> > R14_svc).  I think this used to be the default, but it's not any more.
> 
> Then it sounds like we need to fix the NetBSD/arm GCC4 configuration.

For userland code, and for arm32 kernel code, the current configuration is 
fine.  It's just arm26 kernel code that needs special handling of R14.  A 
special option that just ensured that R14 was saved before any accesses 
to non-stack memory might be nice, but I'm not sure it would be worth the 
maintenance effort.  If we were to need to cope with page faults on stack 
accesses or on kernel code that would be different, but I hope that won't 
turn out to be necessary.

-- 
Ben Harris                                                   <bjh21@NetBSD.org>
Portmaster, NetBSD/acorn26               <http://www.NetBSD.org/Ports/acorn26/>