Christian writes: > Hi List (James:-) > > I have still some issues with my litle project. Let me explain for short > what i'm doing: > > > Application (synchdlc) <---> Stdin/Stdout <----> pppd (synchdlc) That diagram doesn't make sense to me. Standard input and output can be open on a pseudoterminal (pty), and pppd will work that way, but ptys accept only async data, not sync. Ptys emulate terminals, which are devices attached to the system by way of asynchronous ports. They don't emulate synchronous interfaces. You'll need to invent your own sort of pty-like driver if you want to run synchronous. > to ensure boundaries i have hacked pppd to add framing for stdin/stdout, > so that packets in pppd transmitted to stdout contain headers and > packets received contain headers as well. That sounds like a brutal hack. What are you trying to do? > My problem is the following: > > I don't understand where exactly the PPP(IP) frames are read in pppd > and transmitted to the master_pty. It is certainly not (only) in > read_packet. I have found out that the kernel writes correct packets > with copy_to_user to the userspace. pppd reads them and somehow > transmits them to the master_fd. At this point the boundaries got lost. > > I have tried to read the pppd code for a while, but i think i can't see > the forest anymore because of all the trees. It's still not at all clear to me what you're trying to do, or why you're doing it. You're using async devices here -- ptys -- so why are you expecting synchronous behavior? -- James Carlson 42.703N 71.076W <carlsonj@xxxxxxxxxxxxxxx> - 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
