RE: [avrdude-dev] avrdude elf implimentation

[Eric Weddington]

> -----Original Message-----
> From: Colin O'Flynn [mailto:address@hidden 
> Sent: Tuesday, March 20, 2007 8:24 AM
> To: Eric Weddington
> Cc: address@hidden; 'Joerg Wunsch'
> Subject: Re: [avrdude-dev] avrdude elf implimentation
> 
> Hey Eric,
> 
> You need to 
> modify the following file in the binutils source:
> 
> binutils/ld/scripttempl/avr.sc
> 
> In the MEMORY section it becomes:
> 
> MEMORY
> {
>   text   (rx)   : ORIGIN = 0, LENGTH = $TEXT_LENGTH
>   data   (rw!x) : ORIGIN = 0x800060, LENGTH = $DATA_LENGTH
>   eeprom (rw!x) : ORIGIN = 0x810000, LENGTH = 64K
>   lfuse  (r!w!x): ORIGIN = 0x820000, LENGTH = 1
>   hfuse  (r!w!x): ORIGIN = 0x820010, LENGTH = 1
>   efuse  (r!w!x): ORIGIN = 0x820020, LENGTH = 1
> }
> 
> and in the SECTION you have to add:
> 
>   .lfuse ${RELOCATING-0} (NOLOAD):
>   {
>     *(.lfuse*)
>   } ${RELOCATING+ > lfuse}
> 
>   .hfuse ${RELOCATING-0} (NOLOAD):
>   {
>     *(.lfuse*)
>   } ${RELOCATING+ > hfuse}
> 
>   .efuse ${RELOCATING-0} (NOLOAD):
>   {
>     *(.lfuse*)
>   } ${RELOCATING+ > efuse}
> 

One small change needs to be done. You have the same input section,
*(.lfuse*), going to all output sections. As a suggestion, I would also add
another input section if we want to create a section for the older AVRs that
just have one fuse byte, and we want to have a separately named .fuse
section. The changes would be:


   .lfuse ${RELOCATING-0} (NOLOAD):
   {
     *(.lfuse*)
     *(.fuse*)
   } ${RELOCATING+ > lfuse}
 
   .hfuse ${RELOCATING-0} (NOLOAD):
   {
     *(.hfuse*)
   } ${RELOCATING+ > hfuse}
 
   .efuse ${RELOCATING-0} (NOLOAD):
   {
     *(.efuse*)
   } ${RELOCATING+ > efuse}


> I'm not 100% sure everything I've done is 'kosher', as I 
> haven't worked with 
> GCC linker scripts before. 

No worries. I'm still a novice myself. But from what I can tell, the above
looks good.

> At any rate it is a binutils 
> change, which takes a 
> while to get officially rolled into the project I take it?

True. But, if everyone agrees, we can certainly start trying it out with
patches in the distros.
 
> As well this change doesn't include anything for the older 
> AVR's that just 
> have a fuse, none of this lfuse/hfuse/efuse fanciness.

See change above.
 
> The idea of having a symbol defined in the ELF file that 
> tells you what AVR 
> you should have is a great idea to me as well... not sure if 
> we need a new 
> section for that?

Let's consider that in another thread. Right now the "architecture" is
already in the elf file. But I agree that the device name in the elf file is
needed. I just don't know if a separate section is needed, or what.

Thanks again for putting this together!

Joerg, what are your thoughts on the matter? Any objection to the direction
that this is going?

Eric