Hi Matthias,

El Thu, Nov 22, 2012 at 09:44:37AM +0100 Matthias Brugger ha dit:

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.

yes, the system call numbers are architecture specific

Documentation/ABI/stable/syscalls:

Note that this interface is different for every architecture
that Linux supports.  Please see the architecture-specific
documentation for details on the syscall numbers that are to
be mapped to each syscall

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?

there are several sources out there explaining this, one is
http://www.ibm.com/developerworks/library/l-system-calls/

best regards

-- 
Matthias Kaehlcke
Embedded Linux Developer
Amsterdam

            There is nothing so useless as doing efficiently
                 that which should not be done at all
                           (Peter Drucker)
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