Re: [avr-gcc-list] Broken R_AVR_16 relocation? Or is my compiler wrong?

[Senthil Kumar Selvaraj]

On Thu, Jan 07, 2016 at 10:55:33PM +1300, Dylan McKay wrote:
> Hello there,
> 
> I am generating AVR executables with my own compiler, but linking them with
> AVR-GCC.
> 
> Here is an example of a C file, which avr-as compiles fine. I made sure to
> first use my compiler to generate assembly from this file, and then
> assemble this using my compiler and gcc so that they are both using the
> same assembly source file.
> 
> void foo();int bar = 2;int abc = 2;
> int jmp __attribute__((section(".vectors"))) = 0x940C;void (*ptr)()
> __attribute__((section(".vectors"))) = (&foo);
> void milan() { }void foo(){}void inter() { }
> int qwerty = 2;
> 
> The .vectors section is generated fine. The correct jmp instruction is
> placed. Both compilers generate R_AVR_16 relocations for this.
> 
> GCC however generates this (avr-objdump output):
> 
> RELOCATION RECORDS FOR [.vectors]:
> OFFSET   TYPE              VALUE
> 00000004 R_AVR_16          .text+0x00000004
> 
> Note that .text+0x00000004 does point to foo in the object file.
> 
> Whereas my compiler generates this:
> 
> RELOCATION RECORDS FOR [.vectors]:
> OFFSET   TYPE              VALUE
> 00000002 R_AVR_16          foo
> 
> The problem is that GCC???s hardcoded section+offset works, but my symbol
> does not. avr-ld correctly relocates GCC code to foo in the executable, but
> relocates my code to _etext+0x2.
> 
> Am I doing something wrong, or is not just not properly supported?
> ???

Hmm, I remember seeing code in gas turning symbol relocs into
sectionstart+offset ones. Give me a day to dig that up.

Regards
Senthil