Message-ID: <49838F39.6060603@zytor.com>
Date: Fri, 30 Jan 2009 15:37:29 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Martin Hicks <mort@sgi.com>
CC: tglx@linutronix.de, mingo@redhat.com, heukelum@mailshack.com,
       linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: push old stack address on irqstack for unwinder
References: <20090130165053.GE7872@alcatraz.americas.sgi.com>
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Martin Hicks wrote:
> Hi,
> 
> KDB was using this information.  Could this be pushed towards 2.6.29 please?
> 
> This re-adds the old stack pointer to the top of the irqstack to help
> with unwinding.  It was removed in commit d99015b1abbad743aa049b439c1e1dede6d0fa49
> as part of the save_args out-of-line work.
> 

This bothers me... why should we add even a single instruction to what 
is arguably the single hottest path in the kernel to support an 
out-of-tree debugger, especially if kgdb (which is in-tree) doesn't need it?

What does kgdb do differently (or is kgdb broken too)?

	-hpa
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