What is R_X86_64_GOTPLT64 used for?

[Richard Henderson]

On 11/13/2014 03:55 PM, H.J. Lu wrote:
> x86-64 psABI has
> 
> name@GOT: specifies the offset to the GOT entry for the symbol name
> from the base of the GOT.
> 
> name@GOTPLT: specifies the offset to the GOT entry for the symbol name
> from the base of the GOT, implying that there is a corresponding PLT entry.
> 
> But GCC never generates name@GOTPLT and assembler fails to assemble
> it:
> 
> [hjl@gnu-6 pr17598]$ cat x.S
> movabs $foo@GOTPLT,%rax
> [hjl@gnu-6 pr17598]$ gcc -c x.S
> x.S: Assembler messages:
> x.S:1: Error: relocated field and relocation type differ in signedness

Presumably that's a bug, since it does work with .quad.

> Does anyone remember what it was supposed to be used for?

Presumably some sort of non-C language where you need a non-local function
pointer, but it need not be canonical, and thus could be lazily bound.

But I don't know exactly when that would be.


r~