Socket options for different architectures (a short question)

Hello, netdev list,

I have a short question about socket options:
why does each architecture has a list of the socket options
it supports in a separate socket.h header ? it seems to me that the list
of these options is identical (I did not verified this though)
Is there a case when some specific platform/platforms define socket
options in a different way ?
Is there a case when some platform supports only part of the socket
options ?
For example, for

SO_DEBUG,SO_REUSEADDR, SO_SNDBUF, etc, we have the same definitions in

 arch/ia64/include/asm/socket.h, arch/xtensa/include/asm/socket.h,
 arch/x86/include/asm/socket.h ,arch/powerpc/include/asm/socket.h and so on.

Regards,
 Kevin