Message-ID: <3FB93EF6.807@steudten.com>
Date: Mon, 17 Nov 2003 22:34:46 +0100
From: Thomas Steudten <alpha@steudten.com>
Reply-To: alpha@steudten.com
Organization: STEUDTEN ENGINEERING
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To: Falk Hueffner <falk.hueffner@student.uni-tuebingen.de>
CC: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
       linux-alpha@vger.kernel.org
Subject: Re: BUG: Kernel Panic: kernel-2.6.0-test9-bk21  for alpha in scsi
 context ll_rw_blk.c
References: <3FB92938.8040906@steudten.com> <87r806d6n6.fsf@student.uni-tuebingen.de>
In-Reply-To: <87r806d6n6.fsf@student.uni-tuebingen.de>
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On http://steudten.com/alpha/perf.php4 you can read:
See prefetch section:
The Alpha 21264 initiates a prefetch operation by executing one of the load 
instructions as summarized in the table below. Note that the destination 
register is R31 or F31. When used as a source register, R31 and F31 return 
integer zero and floating point zero, respectively. When used as a 
destination register as shown below, R31 and F31 denote the purpose of 
these instructions as a prefetch operation. Earlier Alpha implementations 
ignore these instructions. Some care must be taken as a prefetch with an 
invalid address must be dismissed by firmware and a prefetch can cause an 
alignment trap.

Tom


Falk Hueffner wrote:

> Thomas Steudten <alpha@steudten.com> writes:
> 
> 
>>-> 0xfffffc0000476cb8 <__make_request+152>:        lds     $f31,0(t2)
> 
> 
> The kernel is stupid, this is a prefetch, it should be totally ignored
> if it is faulty. This is already handled for userspace accesses
> IIRC... (I wonder why the PALcode doesn't already do that. Oh well.)
> 

-- 
Tom

LINUX user since kernel 0.99.x 1994.
RPM Alpha packages at http://alpha.steudten.com/packages
Want to know what S.u.S.E 1995 cdrom-set contains?


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