Date: Sun, 10 Sep 2006 09:33:07 -0700
From: Andrew Morton <akpm@osdl.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <ak@suse.de>, Laurent Riffard <laurent.riffard@free.fr>,
       Arjan van de Ven <arjan@infradead.org>,
       Kernel development list <linux-kernel@vger.kernel.org>,
       Jeremy Fitzhardinge <jeremy@xensource.com>
Subject: Re: 2.6.18-rc6-mm1: GPF loop on early boot
Message-Id: <20060910093307.a011b16f.akpm@osdl.org>
In-Reply-To: <20060910132614.GA29423@elte.hu>
References: <20060908011317.6cb0495a.akpm@osdl.org>
	<200609101032.17429.ak@suse.de>
	<20060910115722.GA15356@elte.hu>
	<200609101334.34867.ak@suse.de>
	<20060910132614.GA29423@elte.hu>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1536
Lines: 32

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?
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/