<HTML ><HEAD ><TITLE >Modem hangs up upon reboot</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="Remote Serial Console HOWTO" HREF="index.html"><LINK REL="UP" TITLE="Bugs and annoyances" HREF="bugs.html"><LINK REL="PREVIOUS" TITLE="BIOSs, keyboards and video cards" HREF="bugs-video.html"><LINK REL="NEXT" TITLE="init and syslog output does not display on secondary consoles" HREF="bugs-monitor.html"></HEAD ><BODY CLASS="SECTION" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Remote Serial Console HOWTO</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="bugs-video.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" >Appendix A. Bugs and annoyances</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="bugs-monitor.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECTION" ><H1 CLASS="SECTION" ><A NAME="BUGS-REBOOT" ></A >A.4. Modem hangs up upon reboot</H1 ><P >During reboot the serial controller is reset. This drops the modem control line Data Terminal Ready. This in turn instructs the modem to hang up.</P ><P >Avoid the temptation to configure the modem to ignore <SPAN CLASS="ACRONYM" >DTR</SPAN >. This leads to a worse bug, where the telephone line does not clear down correctly, the modem is engaged, and there is no way to clear it. Ignoring <SPAN CLASS="ACRONYM" >DTR</SPAN > also gives no way to clear hostile callers from the line.</P ><P >You may wish to record the amount of time that the computer takes from <TT CLASS="COMPUTEROUTPUT" >Restarting system</TT > to the boot loader prompt.</P ><P >The modem may also hang up during the boot process (as the serial chip is reset) or when the <SPAN CLASS="APPLICATION" >init</SPAN > run level is changed (as <SPAN CLASS="APPLICATION" >getty</SPAN > is restarted).</P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="bugs-video.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="bugs-monitor.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><SPAN CLASS="ACRONYM" >BIOS</SPAN >s, keyboards and video cards</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="bugs.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><SPAN CLASS="APPLICATION" >init</SPAN > and <SPAN CLASS="APPLICATION" >syslog</SPAN > output does not display on secondary consoles</TD ></TR ></TABLE ></DIV ></BODY ></HTML >
