Re: [U-Boot-Users] Relocation of code/data in a dynamic linker absent system.

12 Jun 2003


      In message 005e01c33108$6140c540$6706a8c0@SPLENDOR you wrote:
...
I would like to start a discussion on the various techniques of
relocation of data & code w.r.t to a non-O.S (no dynamic linker) system.
The idea is to compare different thoughts and bring out the best
possibility.
The "best" solution often depends on  your  requirements.  Maybe  you
should first define what you intend to do...
I understand that you are  talking  about  statically  linked  images
only, right?
...
To start with,I myself know of a relocation technique, as used by GNU
toochians : The concept of VMA/LMA... We link the code in such a way
that we have a different execution address(VMA) and a load address(LMA).
All we need to do in our initializaton code is to copy the data/text
from LMA to VMA before we really start using the data/text.
Actually this is NOT what we call relocation.
Relocation means to modify the instruction and relocation fileds in a
relocatable, executable or shared object file to create an executable
or shared object file.
See the System V ABI  /  PowerPC  Processor  Supplement  for  deatils
(setion 4-3 Relocation, section 5-4 Dynamic Linking).
Best regards,
Wolfgang Denk
-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
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