powerpc-unknown-eabi rom relocation

Vaughan Hillman hillman_97@yahoo.com
Wed Sep 2 20:52:00 GMT 1998


Ive got a cross compiler for the powerpc-eabi 
hosted on under sunos.  I am trying to build
a rom image that when loaded to the bootprom will move its data
sections to ram.  I have compiled all source files with
-mrelocatable-lib (not sure if this flag directly relates to what Im
trying to accomplish).  For testing purposes I have been trying to
relocate the .sdata section by using the following line in my linker
file.

.sdata 0x10000 : AT (0x50000) { *(*.sdata) }

My understanding of what this line means is the following.  .sdata
will be put at address 0x10000 in 
the rom image but all references to this area (by code) will point to
address offset 0x50000.  My code would then be responsible for copying
this data from rom address to 0x10000 out to ram address 0x50000.  The
map
file indicates that all variables in this section as being from offset
0x10000 but it also says that the sections load area is at 0x50000. 
When looking at the code from the debugger all references to variables
from this section seem to be from 0x10000 and not the expected
0x50000.  When looking at the assembly the relocatable code seems to
be getting the offset of the .sdata section from an offset of the
value returned by the ld register. It just seems that the offset
0x50000 is not being put there.


I have sifted through all the documentation for the linker file and
gcc options at the Cygnus site and still seem to be stuck.  

Are my assumptions on how the AT tag work correct?
Is the -mrelocatable-lib flag supposed to be helping
me with relocating this section?

Any help would be greatly appreciated,

Thanks,
	Vaughan 
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