On Sun, Apr 01, 2007 at 12:56:26PM -0400, Robert P. J. Day wrote: > > he describes what are pretty clearly userspace calls such as > llseek(), read(), aio_read() and so on as "system calls". that's not > what i understand by the phrase "system calls." > > i've always used that description to refer to what love talks about > in ch 5, "system calls." from my perspective, an actual system call > from userspace would look like what love has on p. 73: > > #define __NR_foo 283 > __syscall0(long, foo) > ... > An actual one would be something like (sys_exit in example): movl $1, %eax # exit() syscall number movl $0, %ebx # the parameter int 0x80 # interrupt vector for syscalls. > and so on; that is, it *explicitly* uses the _syscalln() macros. > IMHO, a simple call to something like read() and write() is simply a > userspace call which *eventually* invokes the corresponding system > call. > read(), write() from userspace are just libc wrappers for appropriate kernel system calls. Remember the last discussion on LKML about adding a new syscall fallocate() ?. They gonna break the parameters in the kernel interface but this will be invisible in the userspace land by using libc wrappers. Regards, -- Ahmed S. Darwish http://darwish.07.googlepages.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
