On Thu, Jan 11, 2001 at 05:26:43PM +0000, Toby Jaffey wrote:
When I played with pppd in 2.4 I had some problems with it not being able to "set line discipline". Basically, I think that pppd could not swap it's connection to /dev/ttySx to a pty once dialling up. Maybe?
The line line discipline determines how a tty device behaves - how characters that pass through the device in each direction get changed or translated and if any other side effects happen as certain special characters are spotted.
The default line discipline is the one that gives us what we would regard as normal tty behaviour including CR and NL translations, erase (backspace) character processing and generating the tty originated signals (SIGINT, SIGTSTP, SIGQUIT etc.)
When pppd wants to use that same tty device to talk PPP it wants to change the rules on how the device behaves and tells the kernel to use a different line discipline - one suited for PPP. The code to implement the line discipline for PPP is in the kernel PPP modules so if the kernel can't load these, or they don't work as expected, the kernel reports back to the pppd that it couldn't set the line discipline as requested, hence the error message.
Steve