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From: Keith Owens <kaos@sgi.com>
To: linux-ia64@vger.kernel.org
Subject: Re: 2.6.5 unwind problem with rp <- r0
Date: Tue, 04 May 2004 02:07:25 +0000	[thread overview]
Message-ID: <6895.1083636445@kao2.melbourne.sgi.com> (raw)
In-Reply-To: <4885.1083211711@kao2.melbourne.sgi.com>

On Mon, 3 May 2004 15:28:18 -0700, 
David Mosberger <davidm@napali.hpl.hp.com> wrote:
>>>>>> On Thu, 29 Apr 2004 14:08:31 +1000, Keith Owens <kaos@sgi.com> said:
>
>  Keith> Unwinding through a kernel thread, we hit
>  Keith> kernel_thread_helper which is called from start_kernel_thread
>  Keith> with unwind data
>
>  Keith>         .save rp, r0 // this is the end of the call-chain
>
>  Keith> The kernel unwinder does not handle this correctly, it spits
>  Keith> unwind.pt_regs_off: bad scratch reg r0 and keeps unwinding,
>  Keith> generating garbage.
>
>For now, I think the best solution is to avoid the idiom.  I don't
>want to make too many changes to the existing kernel unwinder anymore.
>That is, I'd rather spend time on a libunwind-based kernel unwinder.

David, you wanted rp <- r0 to get a clean termination of the unwind
chain.  Without that clean termination, unwind wanders off into nowhere
generating garbage.  This has already confused at least two people.


  parent reply	other threads:[~2004-05-04  2:07 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2004-04-29  4:08 2.6.5 unwind problem with rp <- r0 Keith Owens
2004-05-03 22:28 ` David Mosberger
2004-05-04  2:07 ` Keith Owens [this message]
2004-05-04 16:40 ` David Mosberger
2004-05-05  0:04 ` Keith Owens
2004-05-05 23:38 ` David Mosberger
2004-05-06  0:08 ` Keith Owens
2004-05-06  0:19 ` David Mosberger
2004-05-06  2:04 ` Keith Owens
2004-05-06  3:42 ` David Mosberger
2004-05-07  8:12 ` Keith Owens
2004-05-11  7:03 ` David Mosberger
2004-05-11 11:32 ` Keith Owens
2004-05-11 16:55 ` David Mosberger

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