[U-Boot-Users] relocate_code

[YanMin Qiao <sepherosa@sohu.com>]

Thank you for your detail answer :) , I see them now.

Best regards


Murray Jensen wrote:

>On Sat, 04 Jan 2003 10:45:27 +0800, YanMin Qiao <sepherosa@sohu.com> writes:
>  
>
>>   First thanks for your answer, howerever, my question is
>>   Why we copy _forward_ when  _memory address_ <CFG_MONITOR_BASE, but 
>>when _memory address_>=CFG_MONITOR_BASE we will have to _copy backword_? 
>>Is it because some overlapping problem when copy?
>>    
>>
>
>Yes. It is generic memory copying code - if it is at all possible that the
>copy might overwrite the destination then it goes backwards, instead of
>forwards. It shouldn't make a lot of difference either way (I guess I can
>imagine a scenario where it stuffs up some fancy pre-fetching in the CPU,
>which might make it go half or a third of the speed, but its not likely).
>
>  
>
>>>Be careful with the first "bge" above - it isn't testing the result of the
>>>previous instruction, it is testing the result of the "cmplw" done quite a
>>>few instructions beforehand and stored in "cr1" i.e. it will branch if "r3"
>>>(the destination address) is >= "r4" (the source address) i.e. if it is
>>>possible that the copy will overwrite the source.
>>>
>>>      
>>>
>>   thanks, I know
>>    
>>
>
>OK, I was just trying to be thorough. Cheers!
>								Murray...
>--
>Murray Jensen, CSIRO Manufacturing & Infra. Tech.      Phone: +61 3 9662 7763
>Locked Bag No. 9, Preston, Vic, 3072, Australia.         Fax: +61 3 9662 7853
>Internet: Murray.Jensen at csiro.au
>
>Hymod project: http://www.msa.cmst.csiro.au/projects/Hymod/
>
>To the extent permitted by law, CSIRO does not represent, warrant and/or
>guarantee that the integrity of this communication has been maintained or
>that the communication is free of errors, virus, interception or interference.
>
>The information contained in this e-mail may be confidential or privileged.
>Any unauthorised use or disclosure is prohibited. If you have received this
>e-mail in error, please delete it immediately and notify Murray Jensen on
>+61 3 9662 7763. Thank you.
>
>
>  
>