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Re: [PATCH 2.5] r4k_switch task_struct/thread_info fixes

To: Vivien Chappelier <vivienc@nerim.net>
Subject: Re: [PATCH 2.5] r4k_switch task_struct/thread_info fixes
From: Jun Sun <jsun@mvista.com>
Date: Fri, 7 Feb 2003 10:40:20 -0800
Cc: Ralf Baechle <ralf@oss.sgi.com>, linux-mips@linux-mips.org, jsun@mvista.com
In-reply-to: <Pine.LNX.4.21.0302071019550.1913-100000@melkor>; from vivienc@nerim.net on Fri, Feb 07, 2003 at 10:29:16AM +0100
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20030206163647.F13258@mvista.com> <Pine.LNX.4.21.0302071019550.1913-100000@melkor>
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On Fri, Feb 07, 2003 at 10:29:16AM +0100, Vivien Chappelier wrote:
> On Thu, 6 Feb 2003, Jun Sun wrote:
> 
> > Actually the following hunks are not right.  ST_OFF
> > should be applied against the task_struct, which is a0,
> > not thread_info (t3).
> 
> In 2.4 yes, not in 2.5.
> 

You are right.  I got misled.  I thought task struct has 2 page 
size and thread_info is allocated from slab.  It should be reverse.

> include/linux/sched.h:469
> > union thread_union {
> >         struct thread_info thread_info;
> >         unsigned long stack[INIT_THREAD_SIZE/sizeof(long)];
> > };
> 
> That means the top of the stack is actually at (task->thread_info +
> KERNEL_STACK_SIZE) in 2.5. See for example arch/mips64/kernel/ptrace.c:107
> 
> > Also see my next email before you rush into trying :-)
> 
> Ok, I'll look at it later.
>

It turns I made a rather stupid comment there as well.  See it there.  :-)

Jun

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