Date: Tue, 9 May 1995 23:15:11 +1000 From: Bruce Evans <bde@zeta.org.au> To: current@FreeBSD.org Subject: misadventures with parallel port tcp/ip Message-ID: <199505091315.XAA08055@godzilla.zeta.org.au>
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I tried the parallel port tcp/ip interface and found the following problems: 1) The BIOS probe fails if lp0 is up at the other end. I have two printer ports and lpt0 configured with `port?' so this caused lp0 to take turns working on the port that was not connected at boot time. 2) The system paniced with a null pointer trap in ifa_ifwithaddr() when I tried the following misconfiguration: ifconfig lp0 inet a0 b0 # a0 and b0 are in /etc/hosts route add b0 a0 # back to front route change a0 A NULL gateway was passed from route_output(). 3) Too much is done at a high ipl. I tried replacing the splhigh()s by splimp()s and everything continued to work even with 39000 interrupts/sec in the background (16000 from pcaudio, 2 * 11500 from 16450's). Ping latency increased from 2ms to 9-20ms with all these interrupts on a 486DX/33. 4) net_imask isn't initialized right in isa.c unless SLIP or PPP is configured. It needs to contain the lpt bit or perhaps all of tty_imask if lpt and INET are configured, at least while lp0 is up. This is approximately always. Bruce
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