Date: Fri, 20 Aug 1999 12:33:13 -0700 From: Kent Stewart <kstewart@3-cities.com> To: Morten Seeberg <morten@seeberg.dk> Cc: questions@FreeBSD.ORG Subject: Re: 4 seriel ports Message-ID: <37BDAD79.59D1A945@3-cities.com> References: <001401beeb3e$21389a90$1600000a@SOS>
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Morten Seeberg wrote: > > Hi, AFAIR it is possible on x86 systems (or atleast windows and dos :) ) to > have 4 serial ports, which share 2 IRQs?? (I have 2 onboard serieal ports > and an xtra I/O card. > How is this done on BSD? And which restrictions would I have, in DOS i > remember, that it wasnt a good idea to put a mouse and a modem on 2 serial > ports, which share IRQ, maybe this problem is solved on newer computers. > > So that: > COM1 IRQ4 > COM2 IRQ3 > COM3 IRQ4 > COM4 IRQ3 > > This doesnt seem possible with the SIO driver (the man says so). But I hope > that it is possible? And where should I look? > > I tried it with the following parameters: > options "COM_MULTIPORT" > device sio0 at isa? port "IO_COM1" tty > device sio1 at isa? port "IO_COM2" tty > device sio2 at isa? port "IO_COM3" tty > device sio3 at isa? port "IO_COM4" tty > > This is the result: > DMESG: > sio0 at 0x3f8-0x3ff on isa > sio0: type 16550A > sio1 at 0x2f8-0x2ff on isa > sio1: type 16550A > sio2 at 0x3e8-0x3ef on isa > sio2: type 16450 > sio3 at 0x2e8-0x2ef on isa > sio3: type 16450 > ----- > fw.home:/root#cu -l /dev/cuaa2 > Connected. > atz > Aug 20 18:21:29 fw /kernel: sio2: 1 more silo overflow (total 2) > Aug 20 18:21:29 fw /kernel: sio2: 1 more silo overflow (total 2) This could be because of how you are sharing interrupts. At some point in my distant past, you could share interrupts but they had to be on the same card. So the add on card would be com2 and com4, which could share an interrupt and com1 and com3 on the PC. You will have problems at some line speed above 9.6kb because you don't have a 16550A on your addon ports, which can cause overflows because the 450 doesn't have the FIFO. Kent > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > /\/\orten $eeberg, Systems Consultant @ > Merkantildata CMA - Enterprise Solutions > #echo 'System Administrators suck :)' > /dev/console > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-questions" in the body of the message -- Kent Stewart Richland, WA mailto:kstewart@3-cities.com http://www.3-cities.com/~kstewart/index.html SETI (Search for Extraterrestrial Intelligence) @ Home http://setiathome.ssl.berkeley.edu/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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