Re: [avr-gcc-list] Support for ATtiny416/417/816/817 ?

[Georg-Johann Lay]

On 05.05.2017 07:53, Pitchumani Sivanupandi wrote:
> On Wednesday 03 May 2017 08:01 PM, Georg-Johann Lay wrote:
> > Hi, the devices in $subject are not yet supported by the tools, mainly
> > because of missing Binutils support.
> >
> > Are there plans to add the needed emulation to Binutils?
>
> These devices are belongs to existing avrxmega2 family.

This emulation might be used but will result in suboptimal code.

For the mentioned devices, we want .rodata to be *not* a part of
data because just like avrtiny, what's definitely preferred is

From avrtiny.x:

__RODATA_PM_OFFSET__ = DEFINED(__RODATA_PM_OFFSET__) ? 
__RODATA_PM_OFFSET__ : 0x4000;

...

  .text :
  {
    ...
  }  > text

  .rodata  ADDR(.text) + SIZEOF (.text) + __RODATA_PM_OFFSET__ :
  {
    *(.rodata)
    *(.rodata*)
    *(.gnu.linkonce.r*)
  } AT> text

  .data :
  {
    PROVIDE (__data_start = .) ;
    *(.data)
    *(.data*)
    *(.gnu.linkonce.d*)
    . = ALIGN(2);
    _edata = . ;
    PROVIDE (__data_end = .) ;
  } > data AT> text


whereas avrxmega2 reads:


  .text :
  {
    ...
  }  > text

  .data :
  {
     PROVIDE (__data_start = .) ;
    *(.data)
    *(.data*)
    *(.rodata)  /* We need to include .rodata here if gcc is used */
    *(.rodata*) /* with -fdata-sections.  */
    *(.gnu.linkonce.d*)
    . = ALIGN(2);
    _edata = . ;
    PROVIDE (__data_end = .) ;
  } > data AT> text


This part of avrtiny.x is what we also want to use for ATtiny816 and
friends, and the canonical way to provide it is to supply a new
emulation for "avrxmega2 + .rodata in flash".


Or are you saying that avrxmega2 like ATXmega16A4 also come with a
linear memory?  I skimmed the data sheet but I found no reference
to that feature.  Maybe the data sheets are outdated or bogus?

The data sheet I found is from June 2013.

Johann