Subject: Re: random signals kill my processes with -current
To: None <firstname.lastname@example.org>
From: Chris G. Demetriou <cgd@CS.cmu.edu>
Date: 01/27/1997 17:37:19
> > > At least, though, we might learn that we need to expand the stack by a
> > > page, or that we have a kernel bug wasting kernel stack. I prefer to
> > > know than not knowing.
> > Actually, what we'd end up seeing is spontaneous reboots.
> > figuring out what's causing an apparently- spontaneous reboot can
> > be ... difficult. 8-)
> No way at all to gracefully deal with the fault when we hit the
> unmapped page?
This is processor-dependent, but on many processors (i'd say "most"
that we run on), the answer is no.
the operative question is "where would the processor put the fault's
stack frame?" it can't put it on the stack, since the next page of
the stack is unmapped (which is the cause of the fault to begin
Some processors support multiple stacks for multiple types of faults.
(i'm pretty sure m68k falls into that category.) That can make this
easier to handle, but it can't be done on all CPU families, and i'm
not even sure about whether or not it can be done on all members of
the m68k family.