RE: newlib with avr-libc support

["Weddington, Eric" <Eric dot Weddington at atmel dot com>]

> -----Original Message-----
> From: newlib-owner@sourceware.org 
> [mailto:newlib-owner@sourceware.org] On Behalf Of Ralf Corsepius
> Sent: Tuesday, June 02, 2009 5:45 AM
> To: Joel Sherrill
> Cc: josh.switnicki@utoronto.ca; newlib@sources.redhat.com
> Subject: Re: newlib with avr-libc support

Hi Ralf,
 
> >> In RTEMS, stuff like interrupts etc. belong into RTEMS, 
> not into newlib.
> >>
> >>   
> > Ralf, the .h files he is merging include all the CPU model
> > ifdef's and IO register names and bit definitions.  avr-libc
> > provides them and you need them to write device drivers,
> => device drivers == RTEMS

The AVR is often used without any kind of OS. Do you have a constructive suggestion on how this functionality should be organized within newlib?


> > bring their setjmp/longjmp over and to write the RTEMS
> > context switch and interrupt vectoring code.
> setjmp/longjmp are supposed to be machine independent and in newlib.
> 
> > The problem he is having is that we need machine/avr/include/XXX
> > to get picked up and installed where XXX is a non-standard
> > directory.  sys/linux does this but it looks like the method has
> > changed since I last looked at it.
> sys/linux is a hack

So, we need another hack. This whole thing is going to be a hack. 

We're trying to cobble together functionality from 3 different projects because,
- We want RTEMS to support the AVR.
- Newlib supports RTEMS.
- Newlib does not have (useful) AVR support.
- AVR-LibC has complete AVR support.
- AVR-LibC does not currently support RTEMS.

There have been two suggested approaches to get RTEMS to support AVR:
- Add functionality from AVR-LibC to Newlib, so Newlib has better AVR support
- Add functionality from Newlib to AVR-LibC, so AVR-Libc has better RTEMS support

Joel has suggested the first. I have suggested the latter. We're both helping out Josh who is working on this as a GSoC project. I know that AVR-LibC (as a project) seems to have a lot more flexibility. But I'm ok if the first route is tried.

Let us know if you have suggestions.