On 13/03/2015 11:41, Dr. David Alan Gilbert wrote: >>> > > +#ifdef HOST_X86_64 >>> > > +#ifndef __NR_userfaultfd >>> > > +#define __NR_userfaultfd 323 >> > >> > Sholdn't this come from the kernel headers imported in the previous >> > patch? Rather than having an arch-specific hack. > The header, like the rest of the kernel headers, just provides > the constant and structure definitions for the call; the syscall numbers > come from arch specific headers. I guess in the final world I wouldn't > need this at all since it'll come from the system headers; but what's > the right way to put this in for new syscalls? >
You would just require new _installed_ kernel headers. Then you can use linux/userfaultfd.h and syscall.h (the latter from glibc, includes asm/unistd.h to get syscall numbers). linux-headers/ is useful for APIs that do not require system calls, or for APIs that are extensible. However, if a system call is required (and mandatory) it's simpler to just use installed headers. Paolo
