Re: 64-bit syscall ABI issue

[David Miller <davem@davemloft.net>]

From: "Joseph S. Myers" <joseph@codesourcery.com>
Date: Mon, 4 Jun 2007 20:56:57 +0000 (UTC)

[ added linux-arch which is a great place to discuss these
  kinds of issues. ]

> What should the kernel syscall ABI be in such cases (any case where the 
> syscall implementations expect arguments narrower than registers, so 
> mainly 32-bit arguments on 64-bit platforms)?  There are two obvious 
> possibilities:

In general we've taken the stance that the syscall dispatch
should create the proper calling environment for C code
implementing the system calls, and this thus means properly
sign and zero extending the arguments as expected by the C
calling convention.