+19200, 38400, 57600, or 115200. The hardware implementation of your
+serial interface card may limit your choice of baud rates. To be precise: the
+frequency of the baud rate clock signal fed into the NSxx50 chips determines
+which baudrates you can select, not the NSxx50 chips themselves.
+.Pp
+All I/O addresses and IRQ levels listed in the config file must
+exactly match the actual setup of the hardware. Note that the AT bus
+does not support multiple cards on a single IRQ line.
+.Pp
+For multiport cards the
+.Nm flags
+keyword in the kernel configuration file determines which device of
+your multiport card is the master device and also indicates that the
+device is part of a multiport card. The master device is the device which
+has the register through which all interrupts of the card are funneled.
+All devices of a multiport card report pending interrupts using this single
+register.
+.sp
+The master device is indicated
+.Nm bitwise
+using bits 8-15. All sio entries in the kernel config file that are part of a
+multiport card must include the correct
+.Nm flags
+specification. The requirement to have a
+.Nm flags
+value on each sio line entry for a multiport card device allows multiple
+multiport cards to be configured in one system. It does
+.Nm not
+imply that the hardware can share the same physical interrupt line!
+.sp
+In the synopsis
+.Nm flags 0x0701
+means that the device with minor number
+.Nm 7
+is the multiport card's master
+device (so the MSB of the flags), and that the devices are on a
+multiport card (the LSB of the flags, actually only the LS
+.Nm bit
+) is used to indicate this. So, in this example the last device of the
+multiport card is the masterdevice.
+.sp
+Note that if you also have non-multiport serial devices controlled by sio,
+as in the
+.Nm Synopsis
+, they do not require
+.Nm flags
+entries but
+.Nm do
+count as serial devices for the calculation of the multiport card's master
+device.
+.sp
+Which device the master device is depends on the card type. Consult
+the hardware documentation of your card to obtain this info.
+.sp
+If you want to disable the FIFO buffers on a sio line with a NS16550A
+chip, you can specify a
+.Nm flags
+value of 0x0002 for a non-multiport line, or OR 0x0002 to the
+.Nm flags
+entry of a multiport line. You can specify this also for a device
+that has no FIFO buffers and it will simply have no effect.
+.sp
+Serial devices controlled by the
+.Nm sio
+driver can be used for both dialin and dialout. Use
+.Nm comcontrol
+command to enable/disable bidirectional use of the
+.Nm sio
+devices. The minor number of the dialout
+device is 128 higher than that of the corresponding dialin device. Use
+.Nm stty(1)
+to enable or disable modem control as required by your setup.
projects / unix-history / blobdiff