[U-Boot-Users] Fixup entries

[Kenneth Johansson]

On Wed, 2008-04-09 at 13:23 +0200, Joakim Tjernlund wrote:
> On Wed, 2008-04-09 at 11:32 +0200, Kenneth Johansson wrote:
> > What is the fixup section used for ?
> > 
> > of the 274 cards that build on my MAKEALL not one has any entries into
> > this section.
> 
> These are needed for relocation of function pointers(and possible some
> think more). There was an attempt by Grant Likely to enable this
> functionalty, but some toolchains had problems with so the function
> was disabled. If you undo commit
> 1c3dd43338a077165e7e0309cb3994e65d2bdbf8 you will enable it again for
> powerpc.
> 
>  Jocke

aaahhaa so that is how it's working. 

I remember having problem understanding this when I did the command
section and ended up doing a manual relocation of the command table. But
compiling with -mrelocatable and going over the .fixup section instead I
can now remove that extra code and it works fine.

It's not easy to understand the ABI.

I removed the -fPIC and only used -mrelocatable and that works too.

Wonder if there is something else in u-boot that use function pointers
and work by accident due to the fact that the old address in flash is
still valid. 

---
`-mrelocatable'
`-mno-relocatable'
     On embedded PowerPC systems generate code that allows (does not
     allow) the program to be relocated to a different address at
     runtime.  If you use `-mrelocatable' on any module, all objects
     linked together must be compiled with `-mrelocatable' or
     `-mrelocatable-lib'.