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RE: Saving arguments on the stack

To: "Ralf Baechle" <ralf@linux-mips.org>
Subject: RE: Saving arguments on the stack
From: "Knittel, Brian" <Brian.Knittel@powertv.com>
Date: Wed, 23 Nov 2005 10:36:31 -0800
Cc: <linux-mips@linux-mips.org>, "Dominic Sweetman" <dom@mips.com>
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
Thread-index: AcXwE/B0diNaHx97QjigLmJi1z4CvAAR57vG
Thread-topic: Saving arguments on the stack
Hi Ralf,
 
I've worked out the backtrace. Changing the compiler is probably not an option. 
One colleague has suggested that with systems with reasonable size caches, not 
saving the arguments on the stack does not provide significant performance 
improvement. I'm sure that depends upon what you are doing, but I suspect he is 
right for the most part. 
 
Comments, anyone?
 
Thanks,
--Brian

        -----Original Message----- 
        From: Ralf Baechle [mailto:ralf@linux-mips.org] 
        Sent: Wed 11/23/2005 1:54 AM 
        To: Knittel, Brian 
        Cc: linux-mips@linux-mips.org; Dominic Sweetman 
        Subject: Re: Saving arguments on the stack
        
        

        On Tue, Nov 22, 2005 at 10:24:09AM -0800, Knittel, Brian wrote:
        
        > We'd like to add arguments to the backtrace in Oops messages to make
        > debugging from these reports more efficient. It is particularly useful
        > for determining where the problem was generated, particularly when bad
        > pointers are passed in. This is for production embedded devices with
        > optimized code and which reboot immediately after storing or sending 
the
        > Oops message. Performance is an issue, but the overhead of storing the
        > arguments on the stack is likely worth the added debug info.
        
        In this case you would probably have to modify the compiler to save all
        arguments.  Another issue is actually finding the stackframe.  For a
        debugger using debug information this is possible but short of that it's
        hard on MIPS to produce a meaningful backtrace.  Or having something
        as complicate as on ia64 ...
        
          Ralf
        

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