177 lines
2.9 KiB
HTML
177 lines
2.9 KiB
HTML
<HTML
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><HEAD
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><TITLE
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>Boot loaders are vulnerable to line noise</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Remote Serial Console HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Bugs and annoyances"
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HREF="bugs.html"><LINK
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REL="PREVIOUS"
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TITLE="Boot loader has no flow control"
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HREF="bugs-bootloaderflow.html"><LINK
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REL="NEXT"
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TITLE="Advanced Power Management"
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HREF="bugs-apm.html"></HEAD
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><BODY
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CLASS="SECTION"
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BGCOLOR="#FFFFFF"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Remote Serial Console HOWTO</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="bugs-bootloaderflow.html"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Appendix A. Bugs and annoyances</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="bugs-apm.html"
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>Next</A
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECTION"
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><H1
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CLASS="SECTION"
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><A
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NAME="BUGS-BOOTLOADERNOISE"
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></A
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>A.9. Boot loaders are vulnerable to line noise</H1
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><P
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>Most boot loaders will sit at their prompt forever after
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receiving a single character of line noise.</P
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><P
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>Some modems will let the <SPAN
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CLASS="ACRONYM"
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>RS-232</SPAN
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> signals
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"float", sending noise when there is no caller. Because the modem
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is not asserting Data Carrier Detect it expects the receiver to
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discard the noise characters.</P
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><P
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>The combination of an unfortunate boot loader with an
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unfortunate modem can result in a machine that will regularly hang
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during booting.</P
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><P
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>If you cannot configure your boot loader to obey
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<SPAN
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CLASS="ACRONYM"
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>DCD</SPAN
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> then be careful to test any modem you intend
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to purchase to ensure that it does not generate characters when
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their is no caller. At the present only
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<SPAN
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CLASS="APPLICATION"
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>SYSLINUX</SPAN
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> implements full
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<SPAN
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CLASS="ACRONYM"
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>RS-232</SPAN
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> status signals.</P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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ALIGN="LEFT"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="bugs-bootloaderflow.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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HREF="bugs-apm.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>Boot loader has no flow control</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="bugs.html"
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ACCESSKEY="U"
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>Up</A
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><SPAN
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CLASS="PRODUCTNAME"
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>Advanced Power Management</SPAN
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></TD
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></TR
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></TABLE
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></BODY
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></HTML
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> |