[U-Boot-Users] why jump at absolute address in start.S

[Murray Jensen <Murray.Jensen@csiro.au>]

On Fri, 03 Jan 2003 09:23:17 +0100, Wolfgang Denk <wd@denx.de> writes:
>> ... my understanding of this ...
...
>
>The "-mrelocatable" thingy has nothing to do with this  part  of  the
>code.  Also,  "-mrelocatable"  does _not_ mean that you can just copy
>the code to a new address and jump into it - it just means  that  the
>compiler  will  generate  enough  information (especially the GOT) so
>that you can relocate the code _manually_.

OK, my understanding was slightly flawed - thank you for pointing out
my error (and in such a friendly manner too). I thought the code needed
"-mrelocatable" for this "execute anywhere" trick, but of course since
it is assembly code there, you simply don't write non-relocatable code.

>> The bit of code above is special - at this point the CPU will be executing
>> at whatever address the reset configuration dictates (for 8xx I think the CP
>U
>...
>> This code jumps to the address that the boot device will appear at after you
>> program the memory controller registers, so that the boot device will not
>> disappear out from underneath you.
>
>_This_ is the correct explanation.

Nice to know I got something right. I wonder if it actually helped anyone
or if I just wasted my time.

>Ummm...
>
>> 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 interferenc
>e.
>> 
>> 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.
>
>Can you please shut off this crap when posting to public mailing lists?

Believe me - I would like to. But I am using CSIRO computers and networks
to post and they have demanded that this disclaimer appear on all external
email - I have to respect their wishes. If I was using their stupid exchange
email system, it would simply append it for me without any choice. At least
with mh-mail I have the option - but I have to be responsible otherwise I
just give them ammunition to shut me down and force me to use their exchange
system (they don't realise that they can't actually stop me short of pulling
the network cable out, but I'm not going to tell them that).

I will of course not post to the list anymore, if you say so. 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.