m68k-coff: Unused memory region included in output file?

Toralf Lund toralf@procaptura.com
Tue Oct 26 15:00:00 GMT 2004

I've been using the following memory region setup for applications 
running on our custom M68K board:

  reserved (rwx) : ORIGIN = 0x000000, LENGTH = 4K
  ram (rwx) : ORIGIN = 0x001000, LENGTH = 1M-4K
  rom (rx) : ORIGIN = 0xF00000, LENGTH = 128K
  user (rx) : ORIGIN = 0xF20000, LENGTH = 768K
  registers (rx): ORIGIN = 0xFE0000, LENGTH = 16K
  sio (rx): ORIGIN = 0xFE4000, LENGTH = 16K
  ivhc (rx): ORIGIN = 0xFE8000, LENGTH = 16K
  vme (rx): ORIGIN = 0xFF0000, LENGTH = 64K

Of these I actually only use "ram", i.e. all sections have "> ram"; the 
rest are included mainly as a reminder of what the memory looks like. 
When building with gcc-2.95.3, it looks like only data from ram is 
included in the output file, but with 3.3.3 it's different - the 
"reserved" region seems to be written, too, even though no output data 
is directed to it. Or at least, the .text segment, which is written to 
the start of "ram" appears at offset 0x1000 of the actual program data 
within the file, while it used to start at the very beginning.

If I change "reserved (rwx)" to "reserved (rx)" this no longer happens. 
Actually that's the way it should have been set up from the beginning, 
and it may not even be such a great idea to include unused regions in 
the first place, but the point is that *something* has changed between 
gcc 2 and 3, and I'd like to know what.

Can anyone enlighten me?

- Toralf

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