On Tue, May 06, 2008 at 11:49:29AM +0800, cyx_mail@xxxxxxxxxxx wrote: > in generic_establish_ppp(): > ioctl(fd, PPPIOCATTCHAN, &chindex) > 1.fd, is the parameter fd a channel's file descriptor or the file > descriptor for "/dev/ppp0"? In the PPPIOCATTCHAN, it is the fd opened from /dev/ppp, but in the PPPIOCGCHAN just prior it is the fd of the tty. The same variable is re-used. > 2.chindex, is this a output parameter or input parameter? what is meaning? At that time, input. In the previous ioctl, it is output. This is obvious because of the error messages in each return status check, and because it is used uninitialised first. You would need to read the kernel source to be certain. Read the Documentation/networking/ppp_generic.txt file. Focus on the definition of channels. Then read the ppp_generic.c source, concentrating on the PPPIOCGCHAN and PPPIOCATTCHAN matches. -- James Cameron http://ftp.hp.com.au/sigs/jc/ -- To unsubscribe from this list: send the line "unsubscribe linux-ppp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
