.\" Copyright 1992, 1993 Rickard E. Faith (faith@cs.unc.edu).\" May be distributed under the GNU General Public License.\" Portions of this text are from the README in setserial-2.01.tar.z,.\" but I can't figure out who wrote that document.  If anyone knows,.\" please tell me.\".\" [tytso:19940519.2239EDT]  I did... - Ted Ts'o (tytso@mit.edu).\".TH SETSERIAL 8 "@RELEASE_MONTH@ @RELEASE_YEAR@" "Setserial @RELEASE_VERSION@.SH NAMEsetserial \- get/set Linux serial port information.SH SYNOPSIS.B setserial.B "[ \-abqvVWz ]"device.BR "[ " parameter1 " [ " arg " ] ] ...".B "setserial -g".B "[ \-abGv ]"device1 ....SH DESCRIPTION.B setserialis a program designed to set and/or report the configuration informationassociated with a serial port.  This information includes what I/Oport and IRQ a particular serial port is using, and whether or not thebreak key should be interpreted as the Secure Attention Key, and soon.During the normal bootup process, only COM ports 1-4 are initialized,using the default I/O ports and IRQ values, as listed below.  In orderto initialize any additional serial ports, or to change the COM 1-4ports to a nonstadard configuration, the.B setserial program should be used.  Typically it is called from an.I rc.serialscript, which is usually run out of .IR /etc/rc.local .The.I deviceargument or arguments specifies the serial device which should be configured orinterrogated.  It will usually have the following form:.BR /dev/cua[0-3] .If no parameters are specified,.B setserialwill print out the port type (i.e., 8250, 16450, 16550, 16550A, etc.), thehardware I/O port, the hardware IRQ line, its "baud base," and some ofits operational flags.If the.B \-goption is given, the arguments to setserial are interpreted as a listof devices for which the characteristics of those devices should beprinted.  Without the .B \-goption, the first argument to setserial is interpreted as the deviceto be modified or characteristics to be printed, and any additionalarguments are interpreted as parameters which should be assignedto that serial device.For the most part, superuser privilege is required to set theconfiguration parameters of a serial port.  A few serial port parameterscan be set by normal users, however, and these will be noted asexceptions in this manual page..SH OPTIONS.B Setserialaccepts the following options:.TP.B \-aWhen reporting the configuration of a serial device, print allavailable information..TP.B \-bWhen reporting the configuration of a serial device, print a summaryof the device's configuration, which might be suitable for printingduring the bootup process, during the /etc/rc script..TP.B \-GPrint out the configuration information of the serial port in a form whichcan be fed back to setserial as command-line arguments..TP.B \-qBe quiet.  .B Setserialwill print fewer lines of output..TP.B \-vBe verbose..B Setserialwill print additional status output..TP.B \-VDisplay version and exit..TP.B \-WDo wild interrupt initialization and exit.  This option is no longer relevant in Linux kernels after version 2.1..TP.B \-zZero out the serial flags before starting to set flags.  This is relatedto the automatic saving of serial flags using the \-G flag..SH PARAMETERSThe following parameters can be assigned to a serial port.All argument values are assumed to be in decimal unless preceeded by "0x"..TP.BR port " port_number"The.B portoption sets the I/O port, as described above..TP.BR irq " irq_number"The.B irqoption sets the hardware IRQ, as described above..TP.BR uart " uart_type"This option is used to set the UART type.  The permitted types are.BR none ,8250, 16450, 16550, 16550A, 16650, 16650V2, 16654, 16750, 16850, 16950, and16954.Using UART type.B nonewill disable the port.Some internal modems are billed as having a "16550A UART with a 1kbuffer".  This is a lie.  They do not have really have a 16550Acompatible UART; instead what they have is a 16450 compatible UARTwith a 1k receive buffer to prevent receiver overruns.  This isimportant, because they do not have a transmit FIFO.  Hence, they arenot compatible with a 16550A UART, and the autoconfiguration processwill correctly identify them as 16450's.  If you attempt to overridethis using the .B uartparameter, you will see dropped characters during file transmissions.These UART's usually have other problems: the.B skip_testparameter also often must be specified..TP.B autoconfigWhen this parameter is given, .B setserialwill ask the kernel to attempt to automatically configure the serialport.  The I/O port must be correctly set; the kernel will attempt todetermine the UART type, and if the.B auto_irq parameter is set, Linux will attempt to automatically determine theIRQ.  The.B autoconfigparameter should be given after the.BR port , auto_irq ", and " skip_testparameters have been specified..TP.B auto_irqDuring autoconfiguration, try to determine the IRQ.  This feature isnot guaranteed to always produce the correct result; some hardwareconfigurations will fool the Linux kernel.  It is generally safer notto use the .B auto_irqfeature, but rather to specify the IRQ to be used explicitly, usingthe.B irq parameter..TP.B ^auto_irqDuring autoconfiguration, do.I nottry to determine the IRQ..TP.B skip_testDuring autoconfiguration, skip the UART test.  Some internal modems donot have National Semiconductor compatible UART's, but have cheapimitations instead.  Some of these cheasy imitations UART's do notfully support the loopback detection mode, which is used by the kernelto make sure there really is a UART at a particular address beforeattempting to configure it.  So for certain internal modems you willneed to specify this parameter so Linux can initialize the UARTcorrectly..TP.B ^skip_testDuring autoconfiguration, do.I notskip the UART test..TP.BR baud_base " baud_base"This option sets the base baud rate, which is the clock frequency dividedby 16.  Normally this value is 115200, which is also the fastest baudrate which the UART can support. .TP.Bspd_hiUse 57.6kb when the application requests 38.4kb.  This parameter may be specified by a non-privileged user..TP.B spd_vhiUse 115kb when the application requests 38.4kb.This parameter may be specified by a non-privileged user..TP.B spd_shiUse 230kb when the application requests 38.4kb.This parameter may be specified by a non-privileged user..TP.B spd_warpUse 460kb when the application requests 38.4kb.This parameter may be specified by a non-privileged user..TP.B spd_custUse the custom divisor to set the speed when the application requests38.4kb.  In this case, the baud rate is the.B baud_basedivided by the.BR divisor .This parameter may be specified by a non-privileged user..TP.B spd_normalUse 38.4kb when the application requests 38.4kb.This parameter may be specified by a non-privileged user..TP.BR divisor " divisor"This option sets the custom divison.  This divisor will be used then the.B spd_custoption is selected and the serial port is set to 38.4kb by theapplication.This parameter may be specified by a non-privileged user..TP.B sakSet the break key at the Secure Attention Key..TP.B ^sakdisable the Secure Attention Key..TP.B fourportConfigure the port as an AST Fourport card..TP.B ^fourportDisable AST Fourport configuration..TP.BR close_delay " delay"Specify the amount of time, in hundredths of a second, that DTR shouldremain low on a serial line after the callout device is closed, beforethe blocked dialin device raises DTR again.  The default value of thisoption is 50, or a half-second delay..TP.BR closing_wait " delay"Specify the amount of time, in hundredths of a second, that the kernelshould wait for data to be transmitted from the serial port whileclosing the port.  If "none" isspecified, no delay will occur. If "infinite" is specified the kernel will wait indefinitely  for the buffered data to be transmitted.  The default setting is 3000 or 30 seconds of delay.  This default is generally appropriate for most devices.  If too long a delay is selected, thenthe serial port may hang for a long time if when a serial port whichis not connected, and has data pending, is closed.  If too short a