On 30/03/2015 16:07, Dr. David Alan Gilbert wrote: >>> > > >> > >> > 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. > OK, so then I could check for ifdef __NR_userfault and then > do the include and I think that would be safe.
I think it's okay. First include syscall.h, then include linux/userfaultfd.h under #ifdef. > Although then what's the best way to tell people to try it out > without an updated libc? They don't need an updated libc, just an updated kernel. syscall.h is just a wrapper around Linux headers. Paolo > Or is it best to modify ./configure to detect it?
