On Fri, 31 May 2002, Jake Burkholder wrote:
> Apparently, On Fri, May 31, 2002 at 05:49:59PM -0700,
> Julian Elischer said words to the effect of;
>
> > interesting but not exactly brief.. :-)
> >
> >
> > On Fri, 31 May 2002, Jake Burkholder wrote:
> >
> > >
> > > The system call stubs in libc are leaf functions; basically just a
> > > trap instruction followed by a return. They do not touch the stack
> > > at all, or change the stack pointer. One of the first few instructions
> > > on entry to the kernel is a save, which rotates the register window
> > > and logically saves the call-safe registers onto the user stack
> > > (the outs become the ins, and the kernel gets new ins and locals,
> > > with the old ones being saved to the user stack once a flush is
> > > performed or they get spilled out).
> >
> > the question is "when does it switch to the kernel stack?"
> > (and back?)
>
> This is not done by the hardware. Its done by the trap code after
> the save is executed.
so if the software did it in the opposite order,
you'd save to the kernel stack?
(I doubt it but I have to ask..)
>
> >
> >
> > >
> > > Here is a reference: http://www.sparc.com/standards/v9.ps.Z
> >
> > downloaded... 300+ pages.. hmm.
> >
> >
> > >
> > > Jake
> > >
>
> To Unsubscribe: send mail to [EMAIL PROTECTED]
> with "unsubscribe freebsd-current" in the body of the message
>
To Unsubscribe: send mail to [EMAIL PROTECTED]
with "unsubscribe freebsd-current" in the body of the message
