NetMos 9835 serial port card

Asad · 03-24-2005, 12:26 AM

I have just bought a 2 serial ports card NM 9835cv and am having a problem installing it under knoppix 3.7 hard disk installed.

If I boot the system with 2.4 kernel and modeprobe parport_serial it detects ttyS4 & ttyS5 ok. Works ok under 2.4 kernel.

But under 2.6.9 kernel modeprobe parport_serial doesnot detect the ports. Is there an updated parport_serial driver that i can install to detect these extra ports.

Another thing that i have seen somewhere while searching that Linux only support 4 serial ports Is this true. I have seen cards with maybe 8 ports, will these work under linux

DaHammer · 03-26-2005, 01:26 AM

Yes, Linux can theoretically support as many serial ports as you want. But the options to do so are controlled via the kernel, so you must enable support for more than the default 4 in your kernel. I booted up Knoppix 3.7 and took a peak at the kernel config files. It's 2.4.27 kernel has support for more than 4 enabled, but the 2.6.9 kernel does not. That's why you only have access to ttyS0 - ttyS3 under it. You'll need to rebuild the kernel to enable it. The 2 options you need are CONFIG_SERIAL_8250_EXTENDED and CONFIG_SERIAL_8250_MANY_PORTS. You can find them at:

Code:

Device Drivers  --->
   Character devices  --->
      Serial drivers  --->
         Extended 8250/16550 serial driver options
           Support more than 4 legacy serial ports (NEW)

in the kernel configuration menu. You may also want to enable some of the other options under the extended options, such as sharing serial interrupts and etc. You may also need to set:

Code:

Device Drivers  --->
   Character devices  --->
      Serial drivers  --->
        (4)   Maximum number of non-legacy 8250/16550 serial ports

to more than 4.

Just curious, are the netmos cards working well? Reason I ask is I bought one a year or so ago, the 4 port variety, and it burned out within days. I replaced it with a 2 port card, also netmos chipset, and ended up throwing it in the junk draw. Neither of them liked 115200 baud very well. Even under Windows. I don't recall if they were 9835 chipset'ed though and they have several different versions I see. But the cards were you're standard El'cheapo brand, forget the name, which probably had alot to do with it.