From: "H. Peter Anvin" <hpa@zytor.com>
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
Date: Fri, 30 Jan 2009 16:35:20 -0800 [thread overview]
Message-ID: <49839CC8.7060502@zytor.com> (raw)
In-Reply-To: <49838F39.6060603@zytor.com>
H. Peter Anvin wrote:
> 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)?
>
Thinking about it some more, I think this makes sense under
#ifdef CONFIG_FRAME_POINTER
... since if we're not building with frame pointers, this is pretty
pointless, and if we are, we're adding these all over the place anyway.
Does this work for you? Let me know and I'll get it in if so.
-hpa
next prev parent reply other threads:[~2009-01-31 0:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-01-30 16:50 [PATCH] x86: push old stack address on irqstack for unwinder Martin Hicks
2009-01-30 23:37 ` H. Peter Anvin
2009-01-31 0:35 ` H. Peter Anvin [this message]
2009-01-31 0:39 ` Ingo Molnar
2009-01-31 0:47 ` H. Peter Anvin
2009-01-31 0:50 ` Ingo Molnar
2009-01-31 17:45 ` Martin Hicks
2009-02-03 5:18 ` H. Peter Anvin
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