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381 lines
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<!-- Created on March, 27 2008 by texi2html 1.64 -->
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<!--
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Written by: Lionel Cons <Lionel.Cons@cern.ch> (original author)
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Karl Berry <karl@freefriends.org>
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Olaf Bachmann <obachman@mathematik.uni-kl.de>
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and many others.
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Maintained by: Olaf Bachmann <obachman@mathematik.uni-kl.de>
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Send bugs and suggestions to <texi2html@mathematik.uni-kl.de>
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<HEAD>
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<TITLE>Debugging with GDB: GDB Bugs</TITLE>
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<META NAME="description" CONTENT="Debugging with GDB: GDB Bugs">
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<META NAME="keywords" CONTENT="Debugging with GDB: GDB Bugs">
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<META NAME="resource-type" CONTENT="document">
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<META NAME="distribution" CONTENT="global">
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<META NAME="Generator" CONTENT="texi2html 1.64">
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</HEAD>
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<BODY LANG="" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#800080" ALINK="#FF0000">
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<A NAME="SEC654"></A>
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<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
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<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_26.html#SEC653"> < </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC655"> > </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_4.html#SEC14"> << </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb.html#SEC_Top"> Up </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_28.html#SEC657"> >> </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb.html#SEC_Top">Top</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_toc.html#SEC_Contents">Contents</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_38.html#SEC764">Index</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_abt.html#SEC_About"> ? </A>]</TD>
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</TR></TABLE>
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<H1> 26. Reporting Bugs in GDB </H1>
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<!--docid::SEC654::-->
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<P>
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Your bug reports play an essential role in making GDB reliable.
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</P><P>
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Reporting a bug may help you by bringing a solution to your problem, or it
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may not. But in any case the principal function of a bug report is to help
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the entire community by making the next version of GDB work better. Bug
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reports are your contribution to the maintenance of GDB.
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</P><P>
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In order for a bug report to serve its purpose, you must include the
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information that enables us to fix the bug.
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</P><P>
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<BLOCKQUOTE><TABLE BORDER=0 CELLSPACING=0>
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<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="gdb_27.html#SEC655">26.1 Have You Found a Bug?</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">Have you found a bug?</TD></TR>
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<TR><TD ALIGN="left" VALIGN="TOP"><A HREF="gdb_27.html#SEC656">26.2 How to Report Bugs</A></TD><TD> </TD><TD ALIGN="left" VALIGN="TOP">How to report bugs</TD></TR>
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</TABLE></BLOCKQUOTE>
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<P>
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<A NAME="Bug Criteria"></A>
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<HR SIZE="6">
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<A NAME="SEC655"></A>
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<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
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<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC654"> < </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC656"> > </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC654"> << </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC654"> Up </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_28.html#SEC657"> >> </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb.html#SEC_Top">Top</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_toc.html#SEC_Contents">Contents</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_38.html#SEC764">Index</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_abt.html#SEC_About"> ? </A>]</TD>
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</TR></TABLE>
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<H2> 26.1 Have You Found a Bug? </H2>
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<!--docid::SEC655::-->
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<P>
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If you are not sure whether you have found a bug, here are some guidelines:
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</P><P>
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<UL>
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<A NAME="IDX1326"></A>
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<A NAME="IDX1327"></A>
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<A NAME="IDX1328"></A>
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<LI>
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If the debugger gets a fatal signal, for any input whatever, that is a
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GDB bug. Reliable debuggers never crash.
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<P>
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<A NAME="IDX1329"></A>
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<LI>
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If GDB produces an error message for valid input, that is a
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bug. (Note that if you're cross debugging, the problem may also be
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somewhere in the connection to the target.)
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<P>
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<A NAME="IDX1330"></A>
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<LI>
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If GDB does not produce an error message for invalid input,
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that is a bug. However, you should note that your idea of
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"invalid input" might be our idea of "an extension" or "support
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for traditional practice".
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<P>
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<LI>
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If you are an experienced user of debugging tools, your suggestions
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for improvement of GDB are welcome in any case.
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</UL>
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<P>
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<A NAME="Bug Reporting"></A>
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<HR SIZE="6">
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<A NAME="SEC656"></A>
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<TABLE CELLPADDING=1 CELLSPACING=1 BORDER=0>
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<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC655"> < </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_28.html#SEC657"> > </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC654"> << </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC654"> Up </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_28.html#SEC657"> >> </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb.html#SEC_Top">Top</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_toc.html#SEC_Contents">Contents</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_38.html#SEC764">Index</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_abt.html#SEC_About"> ? </A>]</TD>
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</TR></TABLE>
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<H2> 26.2 How to Report Bugs </H2>
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<!--docid::SEC656::-->
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<P>
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A number of companies and individuals offer support for GNU products.
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If you obtained GDB from a support organization, we recommend you
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contact that organization first.
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</P><P>
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You can find contact information for many support companies and
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individuals in the file <TT>`etc/SERVICE'</TT> in the GNU Emacs
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distribution.
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</P><P>
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In any event, we also recommend that you submit bug reports for
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GDB. The preferred method is to submit them directly using
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<A HREF="http://www.gnu.org/software/gdb/bugs/">GDB's Bugs web
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page</A>. Alternatively, the <A HREF="mailto:bug-gdb@gnu.org">e-mail gateway</A> can
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be used.
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</P><P>
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<STRONG>Do not send bug reports to <SAMP>`info-gdb'</SAMP>, or to
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<SAMP>`help-gdb'</SAMP>, or to any newsgroups.</STRONG> Most users of GDB do
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not want to receive bug reports. Those that do have arranged to receive
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<SAMP>`bug-gdb'</SAMP>.
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</P><P>
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The mailing list <SAMP>`bug-gdb'</SAMP> has a newsgroup <SAMP>`gnu.gdb.bug'</SAMP> which
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serves as a repeater. The mailing list and the newsgroup carry exactly
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the same messages. Often people think of posting bug reports to the
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newsgroup instead of mailing them. This appears to work, but it has one
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problem which can be crucial: a newsgroup posting often lacks a mail
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path back to the sender. Thus, if we need to ask for more information,
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we may be unable to reach you. For this reason, it is better to send
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bug reports to the mailing list.
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</P><P>
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The fundamental principle of reporting bugs usefully is this:
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<STRONG>report all the facts</STRONG>. If you are not sure whether to state a
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fact or leave it out, state it!
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</P><P>
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Often people omit facts because they think they know what causes the
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problem and assume that some details do not matter. Thus, you might
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assume that the name of the variable you use in an example does not matter.
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Well, probably it does not, but one cannot be sure. Perhaps the bug is a
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stray memory reference which happens to fetch from the location where that
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name is stored in memory; perhaps, if the name were different, the contents
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of that location would fool the debugger into doing the right thing despite
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the bug. Play it safe and give a specific, complete example. That is the
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easiest thing for you to do, and the most helpful.
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</P><P>
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Keep in mind that the purpose of a bug report is to enable us to fix the
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bug. It may be that the bug has been reported previously, but neither
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you nor we can know that unless your bug report is complete and
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self-contained.
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</P><P>
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Sometimes people give a few sketchy facts and ask, "Does this ring a
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bell?" Those bug reports are useless, and we urge everyone to
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<EM>refuse to respond to them</EM> except to chide the sender to report
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bugs properly.
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</P><P>
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To enable us to fix the bug, you should include all these things:
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</P><P>
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<UL>
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<LI>
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The version of GDB. GDB announces it if you start
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with no arguments; you can also print it at any time using <CODE>show
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version</CODE>.
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<P>
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Without this, we will not know whether there is any point in looking for
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the bug in the current version of GDB.
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</P><P>
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<LI>
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The type of machine you are using, and the operating system name and
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version number.
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<P>
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<LI>
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What compiler (and its version) was used to compile GDB---e.g.
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"gcc--2.8.1".
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<P>
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<LI>
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What compiler (and its version) was used to compile the program you are
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debugging--e.g. "gcc--2.8.1", or "HP92453-01 A.10.32.03 HP
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C Compiler". For GCC, you can say <KBD>gcc --version</KBD>
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to get this information; for other compilers, see the documentation for
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those compilers.
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<P>
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<LI>
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The command arguments you gave the compiler to compile your example and
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observe the bug. For example, did you use <SAMP>`-O'</SAMP>? To guarantee
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you will not omit something important, list them all. A copy of the
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Makefile (or the output from make) is sufficient.
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<P>
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If we were to try to guess the arguments, we would probably guess wrong
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and then we might not encounter the bug.
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</P><P>
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<LI>
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A complete input script, and all necessary source files, that will
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reproduce the bug.
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<P>
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<LI>
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A description of what behavior you observe that you believe is
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incorrect. For example, "It gets a fatal signal."
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<P>
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Of course, if the bug is that GDB gets a fatal signal, then we
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will certainly notice it. But if the bug is incorrect output, we might
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not notice unless it is glaringly wrong. You might as well not give us
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a chance to make a mistake.
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</P><P>
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Even if the problem you experience is a fatal signal, you should still
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say so explicitly. Suppose something strange is going on, such as, your
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copy of GDB is out of synch, or you have encountered a bug in
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the C library on your system. (This has happened!) Your copy might
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crash and ours would not. If you told us to expect a crash, then when
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ours fails to crash, we would know that the bug was not happening for
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us. If you had not told us to expect a crash, then we would not be able
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to draw any conclusion from our observations.
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</P><P>
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<A NAME="IDX1331"></A>
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<A NAME="IDX1332"></A>
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To collect all this information, you can use a session recording program
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such as <CODE>script</CODE>, which is available on many Unix systems.
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Just run your GDB session inside <CODE>script</CODE> and then
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include the <TT>`typescript'</TT> file with your bug report.
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</P><P>
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Another way to record a GDB session is to run GDB
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inside Emacs and then save the entire buffer to a file.
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</P><P>
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<LI>
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If you wish to suggest changes to the GDB source, send us context
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diffs. If you even discuss something in the GDB source, refer to
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it by context, not by line number.
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<P>
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The line numbers in our development sources will not match those in your
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sources. Your line numbers would convey no useful information to us.
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</P><P>
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</UL>
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<P>
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Here are some things that are not necessary:
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</P><P>
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<UL>
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<LI>
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A description of the envelope of the bug.
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<P>
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Often people who encounter a bug spend a lot of time investigating
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which changes to the input file will make the bug go away and which
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changes will not affect it.
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</P><P>
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This is often time consuming and not very useful, because the way we
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will find the bug is by running a single example under the debugger
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with breakpoints, not by pure deduction from a series of examples.
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We recommend that you save your time for something else.
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</P><P>
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Of course, if you can find a simpler example to report <EM>instead</EM>
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of the original one, that is a convenience for us. Errors in the
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output will be easier to spot, running under the debugger will take
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less time, and so on.
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</P><P>
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However, simplification is not vital; if you do not want to do this,
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report the bug anyway and send us the entire test case you used.
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</P><P>
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<LI>
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A patch for the bug.
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<P>
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A patch for the bug does help us if it is a good one. But do not omit
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the necessary information, such as the test case, on the assumption that
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a patch is all we need. We might see problems with your patch and decide
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to fix the problem another way, or we might not understand it at all.
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</P><P>
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Sometimes with a program as complicated as GDB it is very hard to
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construct an example that will make the program follow a certain path
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through the code. If you do not send us the example, we will not be able
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to construct one, so we will not be able to verify that the bug is fixed.
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</P><P>
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And if we cannot understand what bug you are trying to fix, or why your
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patch should be an improvement, we will not install it. A test case will
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help us to understand.
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</P><P>
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<LI>
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A guess about what the bug is or what it depends on.
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<P>
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Such guesses are usually wrong. Even we cannot guess right about such
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things without first using the debugger to find the facts.
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</UL>
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<P>
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<A NAME="Command Line Editing"></A>
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<HR SIZE="6">
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<TR><TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_27.html#SEC654"> << </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_28.html#SEC657"> >> </A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT"> <TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb.html#SEC_Top">Top</A>]</TD>
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<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_toc.html#SEC_Contents">Contents</A>]</TD>
|
|
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_38.html#SEC764">Index</A>]</TD>
|
|
<TD VALIGN="MIDDLE" ALIGN="LEFT">[<A HREF="gdb_abt.html#SEC_About"> ? </A>]</TD>
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</TR></TABLE>
|
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<BR>
|
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<FONT SIZE="-1">
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<address>
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<p>Please send FSF & GNU inquiries & questions to <a
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href="mailto:gnu@gnu.org">gnu@gnu.org</a>. There are also <a
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href="http://www.gnu.org/home.html#ContactInfo">other ways to
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contact</a> the FSF.</p>
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<p>These pages are maintained by <a
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href="http://www.gnu.org/software/gdb/">the GDB developers</a>.</p>
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<p>Copyright Free Software Foundation, Inc., 59 Temple Place - Suite
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330, Boston, MA 02111, USA.</p>
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<p>Verbatim copying and distribution of this entire article is
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permitted in any medium, provided this notice is preserved.</p>
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</address>
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This document was generated
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by <I>GDB Administrator</I> on <I>March, 27 2008</I>
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using <A HREF="http://www.mathematik.uni-kl.de/~obachman/Texi2html
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"><I>texi2html</I></A>
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