Julian Elischer wrote: > Poul-Henning Kamp wrote: >> In message <20080526161608.GE64397_at_hoeg.nl>, Ed Schouten writes: >> >>> The new TTY layer should still support line disciplines, [...] >> >> Actually... I think it shouldn't. >> >> Line-disc's were introduced to interface weird-ass hardware like >> digitizing tablets that had very high data rates, but very little >> information (16 bit X, 16 bit Y and a couple of buttons, like modern >> mice) which would cost inordinate amounts of CPU time to support >> in userland on a VAX computer. >> >> If_slip.c happened in the kernel because there was no tun device, >> people cranked the speed up all they could (Hands up: who has changed >> the Xtal on a VAX serial port for faster SLIP ?) >> >> if_ppp happened because that was how if_slip did it. >> >> Today there is no longer a market for line disciplines and in >> practice we have only one: the POSIX mandated "termios", which also >> emulates the older "termio" ioctls. >> >> Anybody who cares to browse the three pages of text that RFC1055 >> contains, will see that implementing SLIP in userland using tun(4) >> and the code on the other three pages of RFC1055 is a trivial task >> not even worthy of a SoC student. >> >> PPP over async is already much better handled in ppp(8) thanks >> to Brians valiant effort back in the stoneage of the internet. >> >> We should summarily kill the concept of line disciplines as a >> modular component and decide that TTYs can be used with termios(4) >> or raw mode and leave it at that. >> >> Poul-Henning >> > > > However the line discipline was a very convenient place for netgraph to > hook in without leaving the kernel. If you can supply an equally > effective way to hook into a serial device in such a way that it appears > to be a source/sink of bits then I don't care about > line disciplins, but until you have a suggested replacement then leave > them alone. There are MANY people using mpd with the netgraph ppp moduel > hooked directly to the serial port via the netgraph line discipline. p.s "do it in userland" is not the right answer, but it should be able to hook into netgraph without all the requirements that were needed for a line discipline. let me contact you independently and we 'll see what can be done. > > _______________________________________________ > freebsd-net_at_freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "freebsd-net-unsubscribe_at_freebsd.org"Received on Tue May 27 2008 - 06:06:11 UTC
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