system call numbers

[Matthias Brugger]

Hi all,

I'm looking into the avr32 architecture implementation, as compiling the 
kernel gives you several warnings about system calls which are missing.

I had a look in the unistd.h file I realized that system call numbers 
differ widely from other architectures (I had a look at arm and x86).
Are the system call numbers platform specific. As far as I understand, 
the system calls are "wrapped" in libc. So I wonder if [g,e,uC]libc uses 
a different system call number each architecture.
A look in the source of uClibc didn't helped me to clear my doubts.

If not all system calls are implemented for avr32:
- is there a problem at all, or does libc implementation take care of 
not implemented system calls?
- if I want to add a system call, what are the steps needed?

Best regards,
Matthias