From Bugzilla Helper:
User-Agent: Mozilla/4.76 [en] (X11; U; Linux 2.4.2-2 i686)

Description of problem:
The fconfigure command is not accepting the -mode option. It reports that
the option isn't supported. This is used to setup serial line parameters in
tcl scripts. 

How reproducible:
Always

Steps to Reproduce:
This code from gpsman package:

proc OpenSerialFailed {baud} {
    # open serial port at given baud rate, and log file if needs be
    # return 1 on failure
    global MESS SRLFILE SERIALPORT InBuff Polling Eof tcl_platform \
	    NotLogging LogFile SERIALLOG

    if { [catch "set SRLFILE [open $SERIALPORT r+]"] } {
	GMMessage [format $MESS(badserial) $SERIALPORT]
	return 1
    }
    switch $tcl_platform(platform) {
	unix {
	    set Polling 0 ; set InBuff ""
	    fconfigure $SRLFILE -blocking 0 -mode $baud,n,8,1 \
		    -translation binary
	    fileevent $SRLFILE readable ReadChar
	}
	windows {
	    # Tcl/Tk 8.0p2 does not support I/O from/to serial ports
	    set Polling 1 ; set InBuff ""
	    fconfigure $SRLFILE -blocking 0 -mode $baud,n,8,1 \
		    -translation binary
	    after 0 ReadChar
	}
	default {
	    GMMessage $MESS(badplatform)
	    return 1
	}
    }
    set Eof 0
    if {! $NotLogging && "$LogFile" == "" } { set LogFile [open $SERIALLOG
w] }
    return 0
}

	

Additional info:

My understanding is that there is a unix capabilities option to compile tcl
that isn't set. 
I read on a newsgroup that this is fixed in Mandrake's tcltk package.