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Re: bug in get_wchan ...

To: Florian Lohoff <flo@rfc822.org>
Subject: Re: bug in get_wchan ...
From: Ralf Baechle <ralf@oss.sgi.com>
Date: Fri, 21 Apr 2000 14:28:07 -0700
Cc: linux@cthulhu.engr.sgi.com
In-reply-to: <20000420182522.B7304@paradigm.rfc822.org>; from flo@rfc822.org on Thu, Apr 20, 2000 at 06:25:22PM +0200
References: <20000420182522.B7304@paradigm.rfc822.org>
Sender: owner-linuxmips@oss.sgi.com
On Thu, Apr 20, 2000 at 06:25:22PM +0200, Florian Lohoff wrote:

> What does "thread_saved_pc(&p->thread);" return ? Does it really
> return the exact address of the schedule functions as assumed in
> 205-214 ?

It's supposed to return the address at which a currently non-executing
process will continue it's execution.

> Most other architectures search the stack page for the calling function
> but it seems their asmlinkage is more strict in the means of 
> location of the return address on the stack.

Yep, unwinding MIPS stackframes is not possible for the general case unless
you use debug information.  We don't want that, so have to use an
alternative solution that is fairly fragile and you're observing yet another
case of this.

Fixing ...

  Ralf

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