[U-Boot] [PATCH] mpc83xx: Add -fpic relocation support

[Joakim Tjernlund]

Scott Wood <scottwood at freescale.com> wrote on 2010/10/12 17:52:58:
> 
> On Tue, 12 Oct 2010 15:04:31 +0200
> Joakim Tjernlund <joakim.tjernlund at transmode.se> wrote:
> 
> > _GLOBAL_OFFSET_TABLE_ is a predefined symbol that the linker defines 
to
> > be in the middle of the -fpic GOT table. It marks the end of the GOT 
table
> > as far as we are concerned(u-boot does not generate so many relocs 
that 
> > the
> > linker needs to use the space above _GLOBAL_OFFSET_TABLE_)
> > 
> > There is no predefined symbol that marks the start of fpic relocs so
> > one is added(_GOT_TABLE_) by me to the linker script.
> 
> Maybe call it _GOT_START_ or similar?  _GLOBAL_OFFSET_TABLE_ and
> _GOT_TABLE_[1] look like synonyms.

hmm, the other reloc syms are named _GOT2_TABLE_ and
_FIXUP_TABLE_ so I think I should follow that.

> 
> -Scott
> 
> [1] Global offset table table? :-)

 :)

Figured I should mention that I have added -msingle-pic-base(from ARM) 
which
works nicely with -fpic(not sure if -fPIC is possible) and reduces size 
even more:
 
size u-boot-before
   text    data     bss     dec     hex filename
 230595    6580   24228  261403   3fd1b u-boot
size u-boot-after
   text    data     bss     dec     hex filename
 222779    6580   24228  253587   3de93 u-boot

If you have 8 KB free DPRAM/cache one can move the GOT tables there
while in flash and create true PIC 

 Jocke