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RE: RM7k cache_flush_sigtramp

To: "'Fuxin Zhang'" <fxzhang@ict.ac.cn>, Ralf Baechle <ralf@linux-mips.org>
Subject: RE: RM7k cache_flush_sigtramp
From: Adam Kiepul <Adam_Kiepul@pmc-sierra.com>
Date: Fri, 1 Aug 2003 08:42:33 -0700
Cc: MAKE FUN PRANK CALLS <linux-mips@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
Hi Fuxin,

Could you please provide me with the _original_ Kernel code disassembly snippet 
around the point where your SYNC patch applies?
Also, can you check what RM7000 part revision is on your board? You can find it 
out by reading the PrID register.

I will check if there is an erratum that the code could trigger.

By the way, are you aware of any other ev64240 board that would exhibit the 
same behavior?

I would be quite careful drawing any conclusions at the moment since we can not 
preclude the possibility that it is simply a "bad CPU on the board" case. 
Please note that the SYNC instruction changes a lot in the manner things 
physically happen in the CPU so it can often mask off various problems, such as 
a bad part.

Thank you,

Adam


-----Original Message-----
From: Fuxin Zhang [mailto:fxzhang@ict.ac.cn]
Sent: Thursday, July 31, 2003 9:59 PM
To: Ralf Baechle
Cc: Adam Kiepul; MAKE FUN PRANK CALLS
Subject: Re: RM7k cache_flush_sigtramp


I am using a slightly modified 2.4.21-pre4,based on cvs of early this 
month(?).
We have merged with latest cvs, I will run it and report the result tonight.


Ralf Baechle wrote:

>Adam,
>
>On Fri, Aug 01, 2003 at 08:40:14AM +0800, Fuxin Zhang wrote:
>
>  
>
>>Current linux code does exactly this. But I was seeing all kinds of 
>>faults occuring around the
>>sigreturn point on the stack without a sync? And a sync does greatly 
>>improve the stablity.
>>
>>    
>>
>>>The ordering does matter however since the Hit_Invalidate_I makes sure the 
>>>write buffer is flushed.
>>>      
>>>
>
>could there be an errata explaining Fuxin's findings?
>
>Fuxin, what version are you running?
>
>  Ralf
>
>
>  
>

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