Referring to a specific symbol in a static library with gold

[Pierre Olivier <polivier at vt dot edu>]

Hello,

First of all this is my first time posting on this mailing list, please forgive
me if somehow I'm doing something wrong.

When laying out symbols in the address space using a linker script, ld allows to
refer to a specific symbol coming from a specific object file inside a static
library with the following syntax:

archive.a:object_file.o(.section.symbol_name)

Using gold rather than ld, it seems that such a directive is ignored. The
linking process succeeds. However, when using this instruction to put a specific
symbol at a specific location with gold and checking the resulting
symbols layout
using nm or having a look at the Map file, the symbol is not in the expected
location.

I made a small test case using a dummy hello world program statically compiled
in its entirety with gcc 5.4.0. The C library is musl libc (last commit on the
master branch from the official git repository). For binutils, I also use the
last commit on the master branch from the official git repository.

I use the linker script to place a specific symbol (.text.exit) from a static
library (musl C library: libc.a) at a specific location in the address space
which is: the first position in the .text section. I'm doing this using the
linker script attached to this email. I also attach my Makefile and the C
program (it's a trivial hello world).

After compiling and linking I'm checking the map file (obtained using the -Map
ld/gold flag) to have a look at the location of .text.exit. Using ld as the
linker, it is indeed in the first position of the text section. Using gold, it
is not (it is present farther in the address space, as if my directive was not
taken into account).

Now, while neither of these work with gold:
musl/lib/libc.a:exit.o(.text.exit);
musl/lib/libc.a(.text.exit);

This works:
*(.text.exit);

Is that a missing feature in gold? or am I doing something wrong, maybe there is
another way to refer to a specific symbol of a specific object file in an
archive using gold?

Thank you very much,

Pierre

Attachment: linker-script.x
Description: Binary data

Attachment: Makefile
Description: Binary data

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
	printf("hello world\n");
	return 0;
}