[U-Boot] Two confusing questions about relocation of code on MPC8548CDS board

[hank peng]

After code is relocated, cpu jumped from flash to RAM, I have two
questions I can't understand. Any help will be appreciated greatly.

1. Because TEXT_BASE=0xfff80000 which points to flash space, after
code is copied from flash to RAM and start to run from RAM, how can
u-boot make sure code
is place independent?
For example, what if I write such code as follows:
<code>
lis r0, LABEL at h
ori r0, r0, LABEL at l
mtlr r0
blr
</code>
Here, symbol "LABEL" must be a value which also points to flash space.
After "blr" is executed, we go back to flash, right?

2. Similar as question 1, if I define a global variable like this in a C file:
static int my_global = 1;
powerpc-linux-readelf command shows that my_global located in .data
section and its symbol value also points to flash space. When running
in RAM, if I want to change its value:
my_global = 2;
I don't know how compilor translate this C code into assembly, if it
uses absolute address to locate my_global, I think writing can't be
operated, so does compilor use relative address to locate my_global?
But how?


-- 
The simplest is not all best but the best is surely the simplest!