recent 8250 serial driver changes in 2.6.x kernels

I purchased a 16c2850 based rs232 four port card and cannot make it work. the vendor says it works in the 2.6.11 kernel but I cannot even compile a kernel that old in my environment: asm errors... The key problem seems to center around the CONFIG_SERIAL_8250_MULTIPORT option that existed in the old kernels but no longer exists in 2.6.17 and up. Now there seems to be a plethora of hardware specific driver modules that replace the MULTIPORT option.

When I try to do a

setserial /dev/ttyS4 port 0x120 irq 12 autoconfig I get the invalid parameter error from setserial. This is after adding nr_uarts=16 to the kernel startup. If I insmod one of the hardware specific drivers then the ttyS4 through ttyS15 become available but none seems to control my hardware correctly.

Any clues? It is a Diamond systems Emerald-MM-Opto four port RS232 and DIO card.

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The default number of serial ports supported in the kernelconfig is (was) four ports. You need to set number of serial ports in the kernel config. You are trying to access the fifth serial port. (/dev/ttyS0, /dev/ttyS1,.../dev/ttyS4). I usually set the kernel config to support 16 serial ports.

You should set "Maximum number of serial ports" and "Maxmum number of serial ports to register at runtime."

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Espen Myrland

You should also enable


This was linux-2-6-18-

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Espen Myrland

been there...done that


The problem is that the MULTIPORTS option went away and now the serial ports above ttyS3 don't seem to exist unless I specifically load a driver for an intelligent multiport that doesn't exist and doesn't match my hardware.

setserial /dev/ttyS4 port 0x120 irq 12 autoconfig ^fourport yields the infamous setserial invalid parameter error even though an isadump shows the uart registers are visible at 0x120-0x13f and an ISR of


the vendor says it worked under 2.6.11 but they won't test or support anything more recent and I can't back down to a kernel two years old.

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