Linker Script: Put a particular file at a later position

问题

I'd like to write a linker script looking something like this:

SECTIONS {
  . = 0x0;
  .startup . : { startup.o(.text) }
  .text : { *(.text) }
  .data : { *(.data) }
  .bss : { *(.bss COMMON) }
  . = 0x4000;
  other.text : { other.o(.text) }
  other.data : { other.o(.data) }
  other.bss : { other.o(.bss) }
}

My intention here is to have, in this order:

a section with the .text from startup.o
.text, .data and .bss containing those sections from all other input files besides other.o
the .text, .data and .bss sections from other.o

Of course there is a problem with the script I've given: other.o is included in the * wildcards used previously, so it doesn't get put in the output section other.

Besides manually listing all the input object files bar other.o in place of the *s, is there a way I can achieve what I want here?

回答1:

You can use section attributes to solve this. Suppose you add the following attribute when declaring functions in that file (or any other file):

void foo() __attribute__ ((section(".specialmem")));

And a similar section definition in your linker script:

.specialmem:
{
    *(.specialmem)
}

You can do the same thing with data/bss (global variables) as well. Assuming you want some files/functions to end up in a specific memory location, it is a good practice to define these memory blocks in your linker file as well and then place them there like:

.specialmem:
{
    *(.specialmem)
} >specialMemBlock

回答2:

You may want to try EXCLUDE_FILE

Something like this: *(EXCLUDE_FILE (other.o) .text .text. )

回答3:

Partial solution: * wildcards are fully-fledged file wildcards. If you're lucky enough that other.o is in a different directory from the other input files, this will work:

SECTIONS {
  . = 0x0;
  .startup . : { foo/startup.o(.text) }
  .text : { foo/*(.text) }
  .data : { foo/*(.data) }
  .bss : { foo/*(.bss COMMON) }
  . = 0x4000;
  other.text : { bar/other.o(.text) }
  other.data : { bar/other.o(.data) }
  other.bss : { bar/other.o(.bss) }
}

来源：https://stackoverflow.com/questions/21418593/linker-script-put-a-particular-file-at-a-later-position

标签

linker

embedded

bare-metal