Re: Linking images at one address, but loading them at another.

[Richard Earnshaw <rearnsha at arm dot com>]

> Hi Richard,
> 
> > However, this image contains symbols, if I try to strip the image
> > (eg to  remove debug data):
> > 
> > arm-elf-strip -g -o os os.gdb 
> > BFD: netbsd: warning: allocated section `.text' not in segment
> 
> Not sure about this one.  It sounds like a bug in strip.  Can you
> create a small example for us to test ?

Attached below.  Should work with pretty much any ELF toolchain.  Note, 
however, that the example is not executable.

Compile with

gcc -g t.c

link with 

ld -T ldscript.sample -o t.gdb t.o

strip with

strip -g -o t t.gdb

> 
> > Is there some other way of setting the load address of a segment 
> > symbolically?
> 
> This sounds like a job for memory regions.  For example this script:

OK, I'll give this a go.  Thanks for the tip.

Richard
PHDRS
{
  headers PT_PHDR PHDRS ;
  text PT_LOAD AT (0x10000) ;
  data PT_LOAD ;
}
SECTIONS
{
  .lotext	0x10000 : { *(.lotext) } :text
  .text		(0xa0110000 + SIZEOF (.lotext)) :
	AT ( LOADADDR(.lotext) + SIZEOF ( .lotext ) ) 
  {
    *(.text)
    *(.glue_7t) *(.glue_7)
  } :text =0
  . = ALIGN(256) + (. & (256 - 1));
  .data    : AT ( LOADADDR(.text) + SIZEOF ( .text ) ) 
  {
    *(.data)
  } :data
  .bss       :
  {
   *(.bss)
   *(COMMON)
   . = ALIGN(32 / 8);
  }
  . = ALIGN(32 / 8);
}
void highfunc(void);
void (*func)(void) = highfunc;

void start() __attribute__((section(".lotext")));

void start()
{
  (*func)();
}

void highfunc()
{
}