Re: Forcing processor...

[Bill Studenmund <skippy%macro.stanford.edu@localhost>]

On Thu, 6 Feb 1997 fear%athenet.net@localhost wrote:

> >     if I understod You correct, You would like to force switch into 
> > supervisor
> >mode from user task (running under NetBSD). If so - there's no way because 
> >kernel 
> >cannot let You to do it.

There should be a way, just not a direct way. :-) One thing which comes to
mind is an lkm which basically just lets you take over. This idea is why
you can't load lkm's if the security level is > 0. :-)

> >     In general right way is to set appropriate bit in MSW. Look at PowerPC
> >documentation for details.

But can you do this manipulation when you're in user mode?? I thought
you're not supposed to be able to just arbitrarily activate the supervisor
bit.

> Actually, I'm in MacOS, in a user task.  I have a theory on changing the 
> bus error vector and then causing a bus error... but I'm not completely 
> sure.

I think that's the right idea, but you might think about using a different
vector. I'm not sure what ones are available, but there might be other,
more-benign one ones. I'm not familiar-enough w/ ppc asm code, but isn't
there one for /0? Try it. 

Take care,

Bill