Re: 2.6.18-rc6-mm1: GPF loop on early boot

Andrew Morton
2006-09-10T16:33:33Z

On Sun, 10 Sep 2006 15:26:14 +0200
Ingo Molnar <mingo@elte.hu> wrote:

> * Andi Kleen <ak@suse.de> wrote:
>
> > > Basically, non-atomic setup of basic architecture state _is_ going to be
> > > a nightmare, lockdep or not, especially if it uses common infrastructure
> > > like 'current', spin_lock() or even something as simple as C functions.
> > > (for example the stack-footprint tracer was once hit by this weakness of
> > > the x86_64 code)
> >
> > I disagree with that. The nightmare is putting stuff that needs so
> > much infrastructure into the most basic operations.
>
> ugh, "having a working current" is "so much infrastructure" ?? Lockdep
> uses a very low amount of infrastructure, considering its complexity: it
> has its own allocator, uses raw spinlocks, raw irq flags ops, it
> basically implements its own infrastructure for everything. Being able
> to access a per-task data area (current) is a quite fundamental thing
> for kernel code.

I must say that having an unreliable early-current is going to be quite a
pita for evermore. Things like mcount-based tricks and
basic-block-profiling-based tricks, for example.

Is it really going to be too messy to fake up some statically-defined gdt
which points at init_task, install that before we call any C at all?