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Info file ./gdb.info, produced by Makeinfo, -*- Text -*- from input file gdb-all.texi. START-INFO-DIR-ENTRY * Gdb: (gdb). The GNU debugger. END-INFO-DIR-ENTRY This file documents the GNU debugger GDB. This is Edition 4.04, March 1992, of `Using GDB: A Guide to the GNU Source-Level Debugger' for GDB Version 4.5. Copyright (C) 1988, 1989, 1990, 1991, 1992 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU General Public License" is included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the section entitled "GNU General Public License" may be included in a translation approved by the Free Software Foundation instead of in the original English. File: gdb.info, Node: Output, Prev: Command Files, Up: Sequences Commands for Controlled Output ============================== During the execution of a command file or a user-defined command, normal GDB output is suppressed; the only output that appears is what is explicitly printed by the commands in the definition. This section describes three commands useful for generating exactly the output you want. `echo TEXT' Print TEXT. Nonprinting characters can be included in TEXT using C escape sequences, such as `\n' to print a newline. *No newline will be printed unless you specify one.* In addition to the standard C escape sequences, a backslash followed by a space stands for a space. This is useful for outputting a string with spaces at the beginning or the end, since leading and trailing spaces are otherwise trimmed from all arguments. To print ` and foo = ', use the command `echo \ and foo = \ '. A backslash at the end of TEXT can be used, as in C, to continue the command onto subsequent lines. For example, echo This is some text\n\ which is continued\n\ onto several lines.\n produces the same output as echo This is some text\n echo which is continued\n echo onto several lines.\n `output EXPRESSION' Print the value of EXPRESSION and nothing but that value: no newlines, no `$NN = '. The value is not entered in the value history either. *Note Expressions: Expressions, for more information on expressions. `output/FMT EXPRESSION' Print the value of EXPRESSION in format FMT. You can use the same formats as for `print'; *note Output formats::., for more information. `printf STRING, EXPRESSIONS...' Print the values of the EXPRESSIONS under the control of STRING. The EXPRESSIONS are separated by commas and may be either numbers or pointers. Their values are printed as specified by STRING, exactly as if your program were to execute printf (STRING, EXPRESSIONS...); For example, you can print two values in hex like this: printf "foo, bar-foo = 0x%x, 0x%x\n", foo, bar-foo The only backslash-escape sequences that you can use in the format string are the simple ones that consist of backslash followed by a letter. File: gdb.info, Node: Emacs, Next: GDB Bugs, Prev: Sequences, Up: Top Using GDB under GNU Emacs ************************* A special interface allows you to use GNU Emacs to view (and edit) the source files for the program you are debugging with GDB. To use this interface, use the command `M-x gdb' in Emacs. Give the executable file you want to debug as an argument. This command starts GDB as a subprocess of Emacs, with input and output through a newly created Emacs buffer. Using GDB under Emacs is just like using GDB normally except for two things: * All "terminal" input and output goes through the Emacs buffer. This applies both to GDB commands and their output, and to the input and output done by the program you are debugging. This is useful because it means that you can copy the text of previous commands and input them again; you can even use parts of the output in this way. All the facilities of Emacs' Shell mode are available for interacting with your program. In particular, you can send signals the usual way--for example, `C-c C-c' for an interrupt, `C-c C-z' for a stop. * GDB displays source code through Emacs. Each time GDB displays a stack frame, Emacs automatically finds the source file for that frame and puts an arrow (`=>') at the left margin of the current line. Emacs uses a separate buffer for source display, and splits the window to show both your GDB session and the source. Explicit GDB `list' or search commands still produce output as usual, but you probably will have no reason to use them. *Warning:* If the directory where your program resides is not your current directory, it can be easy to confuse Emacs about the location of the source files, in which case the auxiliary display buffer will not appear to show your source. GDB can find programs by searching your environment's `PATH' variable, so the GDB input and output session will proceed normally; but Emacs does not get enough information back from GDB to locate the source files in this situation. To avoid this problem, either start GDB mode from the directory where your program resides, or specify a full path name when prompted for the `M-x gdb' argument. A similar confusion can result if you use the GDB `file' command to switch to debugging a program in some other location, from an existing GDB buffer in Emacs. By default, `M-x gdb' calls the program called `gdb'. If you need to call GDB by a different name (for example, if you keep several configurations around, with different names) you can set the Emacs variable `gdb-command-name'; for example, (setq gdb-command-name "mygdb") (preceded by `ESC ESC', or typed in the `*scratch*' buffer, or in your `.emacs' file) will make Emacs call the program named "`mygdb'" instead. In the GDB I/O buffer, you can use these special Emacs commands in addition to the standard Shell mode commands: `C-h m' Describe the features of Emacs' GDB Mode. `M-s' Execute to another source line, like the GDB `step' command; also update the display window to show the current file and location. `M-n' Execute to next source line in this function, skipping all function calls, like the GDB `next' command. Then update the display window to show the current file and location. `M-i' Execute one instruction, like the GDB `stepi' command; update display window accordingly. `M-x gdb-nexti' Execute to next instruction, using the GDB `nexti' command; update display window accordingly. `C-c C-f' Execute until exit from the selected stack frame, like the GDB `finish' command. `M-c' Continue execution of your program, like the GDB `continue' command. *Warning:* In Emacs v19, this command is `C-c C-p'. `M-u' Go up the number of frames indicated by the numeric argument (*note Numeric Arguments: (emacs)Arguments.), like the GDB `up' command. *Warning:* In Emacs v19, this command is `C-c C-u'. `M-d' Go down the number of frames indicated by the numeric argument, like the GDB `down' command. *Warning:* In Emacs v19, this command is `C-c C-d'. `C-x &' Read the number where the cursor is positioned, and insert it at the end of the GDB I/O buffer. For example, if you wish to disassemble code around an address that was displayed earlier, type `disassemble'; then move the cursor to the address display, and pick up the argument for `disassemble' by typing `C-x &'. You can customize this further on the fly by defining elements of the list `gdb-print-command'; once it is defined, you can format or otherwise process numbers picked up by `C-x &' before they are inserted. A numeric argument to `C-x &' will both indicate that you wish special formatting, and act as an index to pick an element of the list. If the list element is a string, the number to be inserted is formatted using the Emacs function `format'; otherwise the number is passed as an argument to the corresponding list element. In any source file, the Emacs command `C-x SPC' (`gdb-break') tells GDB to set a breakpoint on the source line point is on. If you accidentally delete the source-display buffer, an easy way to get it back is to type the command `f' in the GDB buffer, to request a frame display; when you run under Emacs, this will recreate the source buffer if necessary to show you the context of the current frame. The source files displayed in Emacs are in ordinary Emacs buffers which are visiting the source files in the usual way. You can edit the files with these buffers if you wish; but keep in mind that GDB communicates with Emacs in terms of line numbers. If you add or delete lines from the text, the line numbers that GDB knows will cease to correspond properly to the code. File: gdb.info, Node: GDB Bugs, Next: Renamed Commands, Prev: Emacs, Up: Top Reporting Bugs in GDB ********************* Your bug reports play an essential role in making GDB reliable. Reporting a bug may help you by bringing a solution to your problem, or it may not. But in any case the principal function of a bug report is to help the entire community by making the next version of GDB work better. Bug reports are your contribution to the maintenance of GDB. In order for a bug report to serve its purpose, you must include the information that enables us to fix the bug. * Menu: * Bug Criteria:: Have You Found a Bug? * Bug Reporting:: How to Report Bugs File: gdb.info, Node: Bug Criteria, Next: Bug Reporting, Prev: GDB Bugs, Up: GDB Bugs Have You Found a Bug? ===================== If you are not sure whether you have found a bug, here are some guidelines: * If the debugger gets a fatal signal, for any input whatever, that is a GDB bug. Reliable debuggers never crash. * If GDB produces an error message for valid input, that is a bug. * If GDB does not produce an error message for invalid input, that is a bug. However, you should note that your idea of "invalid input" might be our idea of "an extension" or "support for traditional practice". * If you are an experienced user of debugging tools, your suggestions for improvement of GDB are welcome in any case. File: gdb.info, Node: Bug Reporting, Prev: Bug Criteria, Up: GDB Bugs How to Report Bugs ================== A number of companies and individuals offer support for GNU products. If you obtained GDB from a support organization, we recommend you contact that organization first. Contact information for many support companies and individuals is available in the file `etc/SERVICE' in the GNU Emacs distribution. In any event, we also recommend that you send bug reports for GDB to one of these addresses: bug-gdb@prep.ai.mit.edu {ucbvax|mit-eddie|uunet}!prep.ai.mit.edu!bug-gdb *Do not send bug reports to `info-gdb', or to `help-gdb', or to any newsgroups.* Most users of GDB do not want to receive bug reports. Those that do, have arranged to receive `bug-gdb'. The mailing list `bug-gdb' has a newsgroup `gnu.gdb.bug' which serves as a repeater. The mailing list and the newsgroup carry exactly the same messages. Often people think of posting bug reports to the newsgroup instead of mailing them. This appears to work, but it has one problem which can be crucial: a newsgroup posting often lacks a mail path back to the sender. Thus, if we need to ask for more information, we may be unable to reach you. For this reason, it is better to send bug reports to the mailing list. As a last resort, send bug reports on paper to: GNU Debugger Bugs Free Software Foundation 545 Tech Square Cambridge, MA 02139 The fundamental principle of reporting bugs usefully is this: *report all the facts*. If you are not sure whether to state a fact or leave it out, state it! Often people omit facts because they think they know what causes the problem and assume that some details do not matter. Thus, you might assume that the name of the variable you use in an example does not matter. Well, probably it does not, but one cannot be sure. Perhaps the bug is a stray memory reference which happens to fetch from the location where that name is stored in memory; perhaps, if the name were different, the contents of that location would fool the debugger into doing the right thing despite the bug. Play it safe and give a specific, complete example. That is the easiest thing for you to do, and the most helpful. Keep in mind that the purpose of a bug report is to enable us to fix the bug if it is new to us. It is not as important as what happens if the bug is already known. Therefore, always write your bug reports on the assumption that the bug has not been reported previously. Sometimes people give a few sketchy facts and ask, "Does this ring a bell?" Those bug reports are useless, and we urge everyone to *refuse to respond to them* except to chide the sender to report bugs properly. To enable us to fix the bug, you should include all these things: * The version of GDB. GDB announces it if you start with no arguments; you can also print it at any time using `show version'. Without this, we will not know whether there is any point in looking for the bug in the current version of GDB. * The type of machine you are using, and the operating system name and version number. * What compiler (and its version) was used to compile GDB--e.g. "gcc-2.0". * What compiler (and its version) was used to compile the program you are debugging--e.g. "gcc-2.0". * The command arguments you gave the compiler to compile your example and observe the bug. For example, did you use `-O'? To guarantee you will not omit something important, list them all. A copy of the Makefile (or the output from make) is sufficient. If we were to try to guess the arguments, we would probably guess wrong and then we might not encounter the bug. * A complete input script, and all necessary source files, that will reproduce the bug. * A description of what behavior you observe that you believe is incorrect. For example, "It gets a fatal signal." Of course, if the bug is that GDB gets a fatal signal, then we will certainly notice it. But if the bug is incorrect output, we might not notice unless it is glaringly wrong. We are human, after all. You might as well not give us a chance to make a mistake. Even if the problem you experience is a fatal signal, you should still say so explicitly. Suppose something strange is going on, such as, your copy of GDB is out of synch, or you have encountered a bug in the C library on your system. (This has happened!) Your copy might crash and ours would not. If you told us to expect a crash, then when ours fails to crash, we would know that the bug was not happening for us. If you had not told us to expect a crash, then we would not be able to draw any conclusion from our observations. * If you wish to suggest changes to the GDB source, send us context diffs. If you even discuss something in the GDB source, refer to it by context, not by line number. The line numbers in our development sources will not match those in your sources. Your line numbers would convey no useful information to us. Here are some things that are not necessary: * A description of the envelope of the bug. Often people who encounter a bug spend a lot of time investigating which changes to the input file will make the bug go away and which changes will not affect it. This is often time consuming and not very useful, because the way we will find the bug is by running a single example under the debugger with breakpoints, not by pure deduction from a series of examples. We recommend that you save your time for something else. Of course, if you can find a simpler example to report *instead* of the original one, that is a convenience for us. Errors in the output will be easier to spot, running under the debugger will take less time, etc. However, simplification is not vital; if you do not want to do this, report the bug anyway and send us the entire test case you used. * A patch for the bug. A patch for the bug does help us if it is a good one. But do not omit the necessary information, such as the test case, on the assumption that a patch is all we need. We might see problems with your patch and decide to fix the problem another way, or we might not understand it at all. Sometimes with a program as complicated as GDB it is very hard to construct an example that will make the program follow a certain path through the code. If you do not send us the example, we will not be able to construct one, so we will not be able to verify that the bug is fixed. And if we cannot understand what bug you are trying to fix, or why your patch should be an improvement, we will not install it. A test case will help us to understand. * A guess about what the bug is or what it depends on. Such guesses are usually wrong. Even we cannot guess right about such things without first using the debugger to find the facts. File: gdb.info, Node: Renamed Commands, Next: Formatting Documentation, Prev: GDB Bugs, Up: Top Renamed Commands **************** The following commands were renamed in GDB 4, in order to make the command set as a whole more consistent and easier to use and remember: OLD COMMAND NEW COMMAND --------------- ------------------------------- add-syms add-symbol-file delete environment unset environment info convenience show convenience info copying show copying info directories show directories info editing show commands info history show values info targets help target info values show values info version show version info warranty show warranty set/show addressprint set/show print address set/show array-max set/show print elements set/show arrayprint set/show print array set/show asm-demangle set/show print asm-demangle set/show caution set/show confirm set/show demangle set/show print demangle set/show history write set/show history save set/show prettyprint set/show print pretty set/show screen-height set/show height set/show screen-width set/show width set/show sevenbit-strings set/show print sevenbit-strings set/show unionprint set/show print union set/show vtblprint set/show print vtbl unset [No longer an alias for delete] File: gdb.info, Node: Formatting Documentation, Next: Installing GDB, Prev: Renamed Commands, Up: Top Formatting the Documentation **************************** The GDB 4 release includes an already-formatted reference card, ready for printing on a PostScript or GhostScript printer, in the `gdb' subdirectory of the main source directory--in `gdb-4.5/gdb/refcard.ps' of the version 4.5 release. If you have a PostScript or GhostScript printer, you can print the reference card by just sending `refcard.ps' to the printer. The release also includes the source for the reference card. You can format it, using TeX, by typing: make refcard.dvi The GDB reference card is designed to print in landscape mode on US "letter" size paper; that is, on a sheet 11 inches wide by 8.5 inches high. You will need to specify this form of printing as an option to your DVI output program. All the documentation for GDB comes as part of the machine-readable distribution. The documentation is written in Texinfo format, which is a documentation system that uses a single source file to produce both on-line information and a printed manual. You can use one of the Info formatting commands to create the on-line version of the documentation and TeX (or `texi2roff') to typeset the printed version. GDB includes an already formatted copy of the on-line Info version of this manual in the `gdb' subdirectory. The main Info file is `gdb-VERSION-NUMBER/gdb/gdb.info', and it refers to subordinate files matching `gdb.info*' in the same directory. If you want to format these Info files yourself, you need one of the Info formatting programs, such as `texinfo-format-buffer' or `makeinfo'. If you have `makeinfo' installed, and are in the top level GDB source directory (`gdb-4.5', in the case of version 4.5), you can make the Info file by typing: cd gdb make gdb.info If you want to typeset and print copies of this manual, you need TeX, a printing program such as `lpr', and `texinfo.tex', the Texinfo definitions file. TeX is typesetting program; it does not print files directly, but produces output files called DVI files. To print a typeset document, you need a program to print DVI files. If your system has TeX installed, chances are it has such a program. The precise command to use depends on your system; `lpr -d' is common; another is `dvips'. The DVI print command may require a file name without any extension or a `.dvi' extension. TeX also requires a macro definitions file called `texinfo.tex'. This file tells TeX how to typeset a document written in Texinfo format. On its own, TeX cannot read, much less typeset a Texinfo file. `texinfo.tex' is distributed with GDB and is located in the `gdb-VERSION-NUMBER/texinfo' directory. If you have TeX and a DVI printer program installed, you can typeset and print this manual. First switch to the the `gdb' subdirectory of the main source directory (for example, to `gdb-4.5/gdb') and then type: make gdb.dvi File: gdb.info, Node: Installing GDB, Next: Copying, Prev: Formatting Documentation, Up: Top Installing GDB ************** GDB comes with a `configure' script that automates the process of preparing GDB for installation; you can then use `make' to build the program. The GDB distribution includes all the source code you need for GDB in a single directory, whose name is usually composed by appending the version number to `gdb'. For example, the GDB version 4.5 distribution is in the `gdb-4.5' directory. That directory contains: `gdb-4.5/configure (and supporting files)' script for configuring GDB and all its supporting libraries. `gdb-4.5/gdb' the source specific to GDB itself `gdb-4.5/bfd' source for the Binary File Descriptor library `gdb-4.5/include' GNU include files `gdb-4.5/libiberty' source for the `-liberty' free software library `gdb-4.5/readline' source for the GNU command-line interface `gdb-4.5/glob' source for the GNU filename pattern-matching subroutine `gdb-4.5/mmalloc' source for the GNU memory-mapped malloc package The simplest way to configure and build GDB is to run `configure' from the `gdb-VERSION-NUMBER' source directory, which in this example is the `gdb-4.5' directory. First switch to the `gdb-VERSION-NUMBER' source directory if you are not already in it; then run `configure'. Pass the identifier for the platform on which GDB will run as an argument. For example: cd gdb-4.5 ./configure HOST make where HOST is an identifier such as `sun4' or `decstation', that identifies the platform where GDB will run. This sequence of `configure' and `make' builds the `bfd', `readline', `mmalloc', and `libiberty' libraries, then `gdb' itself. The configured source files, and the binaries, are left in the corresponding source directories. `configure' is a Bourne-shell (`/bin/sh') script; if your system does not recognize this automatically when you run a different shell, you may need to run `sh' on it explicitly: sh configure HOST If you run `configure' from a directory that contains source directories for multiple libraries or programs, such as the `gdb-4.5' source directory for version 4.5, `configure' creates configuration files for every directory level underneath (unless you tell it not to, with the `--norecursion' option). You can run the `configure' script from any of the subordinate directories in the GDB distribution, if you only want to configure that subdirectory; but be sure to specify a path to it. For example, with version 4.5, type the following to configure only the `bfd' subdirectory: cd gdb-4.5/bfd ../configure HOST You can install `gdb' anywhere; it has no hardwired paths. However, you should make sure that the shell on your path (named by the `SHELL' environment variable) is publicly readable. Remember that GDB uses the shell to start your program--some systems refuse to let GDB debug child processes whose programs are not readable. * Menu: * Separate Objdir:: Compiling GDB in another directory * Config Names:: Specifying names for hosts and targets * configure Options:: Summary of options for configure File: gdb.info, Node: Separate Objdir, Next: Config Names, Prev: Installing GDB, Up: Installing GDB Compiling GDB in Another Directory ================================== If you want to run GDB versions for several host or target machines, you'll need a different `gdb' compiled for each combination of host and target. `configure' is designed to make this easy by allowing you to generate each configuration in a separate subdirectory, rather than in the source directory. If your `make' program handles the `VPATH' feature (GNU `make' does), running `make' in each of these directories then builds the `gdb' program specified there. To build `gdb' in a separate directory, run `configure' with the `--srcdir' option to specify where to find the source. (You'll also need to specify a path to find `configure' itself from your working directory. If the path to `configure' would be the same as the argument to `--srcdir', you can leave out the `--srcdir' option; it will be assumed.) For example, with version 4.5, you can build GDB in a separate directory for a Sun 4 like this: cd gdb-4.5 mkdir ../gdb-sun4 cd ../gdb-sun4 ../gdb-4.5/configure sun4 make When `configure' builds a configuration using a remote source directory, it creates a tree for the binaries with the same structure (and using the same names) as the tree under the source directory. In the example, you'd find the Sun 4 library `libiberty.a' in the directory `gdb-sun4/libiberty', and GDB itself in `gdb-sun4/gdb'. One popular use for building several GDB configurations in separate directories is to configure GDB for cross-compiling (where GDB runs on one machine--the host--while debugging programs that run on another machine--the target). You specify a cross-debugging target by giving the `--target=TARGET' option to `configure'. When you run `make' to build a program or library, you must run it in a configured directory--whatever directory you were in when you called `configure' (or one of its subdirectories). The `Makefile' generated by `configure' for each source directory also runs recursively. If you type `make' in a source directory such as `gdb-4.5' (or in a separate configured directory configured with `--srcdir=PATH/gdb-4.5'), you will build all the required libraries, then build GDB. When you have multiple hosts or targets configured in separate directories, you can run `make' on them in parallel (for example, if they are NFS-mounted on each of the hosts); they will not interfere with each other. File: gdb.info, Node: Config Names, Next: configure Options, Prev: Separate Objdir, Up: Installing GDB Specifying Names for Hosts and Targets ====================================== The specifications used for hosts and targets in the `configure' script are based on a three-part naming scheme, but some short predefined aliases are also supported. The full naming scheme encodes three pieces of information in the following pattern: ARCHITECTURE-VENDOR-OS For example, you can use the alias `sun4' as a HOST argument or in a `--target=TARGET' option, but the equivalent full name is `sparc-sun-sunos4'. The following table shows all the architectures, hosts, and OS prefixes that `configure' recognizes in GDB version 4.5. Entries in the "OS prefix" column ending in a `*' may be followed by a release number. ARCHITECTURE VENDOR OS prefix ------------+--------------------------+--------------------------- | | 580 | altos hp | aix* msdos* a29k | amd ibm | amigados newsos* alliant | amdahl intel | aout nindy* arm | aout isi | bout osf* c1 | apollo little | bsd* sco* c2 | att mips | coff sunos* cray2 | bcs motorola | ctix* svr4 h8300 | bout ncr | dgux* sym* i386 | bull next | dynix* sysv* i860 | cbm nyu | ebmon ultrix* i960 | coff sco | esix* unicos* m68000 | convergent sequent | hds unos* m68k | convex sgi | hpux* uts m88k | cray sony | irix* v88r* mips | dec sun | isc* vms* ns32k | encore unicom | kern vxworks* pyramid | gould utek | mach* romp | hitachi wrs | rs6000 | | sparc | | tahoe | | tron | | vax | | xmp | | ymp | | *Warning:* `configure' can represent a very large number of combinations of architecture, vendor, and OS. There is by no means support available for all possible combinations! The `configure' script accompanying GDB does not provide any query facility to list all supported host and target names or aliases. `configure' calls the Bourne shell script `config.sub' to map abbreviations to full names; you can read the script, if you wish, or you can use it to test your guesses on abbreviations--for example: % sh config.sub sun4 sparc-sun-sunos4 % sh config.sub sun3 m68k-sun-sunos4 % sh config.sub decstation mips-dec-ultrix % sh config.sub hp300bsd m68k-hp-bsd % sh config.sub i386v i386-none-sysv % sh config.sub i786v *** Configuration "i786v" not recognized `config.sub' is also distributed in the GDB source directory (`gdb-4.5', for version 4.5). File: gdb.info, Node: configure Options, Prev: Config Names, Up: Installing GDB `configure' Options =================== Here is a summary of all the `configure' options and arguments that you might use for building GDB: configure [--srcdir=PATH] [--norecursion] [--rm] [--target=TARGET] HOST You may introduce options with a single `-' rather than `--' if you prefer; but you may abbreviate option names if you use `--'. `--srcdir=PATH' *Warning: using this option requires GNU `make', or another `make' that implements the `VPATH' feature.* Use this option to make configurations in directories separate from the GDB source directories. Among other things, you can use this to build (or maintain) several configurations simultaneously, in separate directories. `configure' writes configuration specific files in the current directory, but arranges for them to use the source in the directory PATH. `configure' will create directories under the working directory in parallel to the source directories below PATH. `--norecursion' Configure only the directory level where `configure' is executed; do not propagate configuration to subdirectories. `--rm' Remove the configuration that the other arguments specify. `--target=TARGET' Configure GDB for cross-debugging programs running on the specified TARGET. Without this option, GDB is configured to debug programs that run on the same machine (HOST) as GDB itself. There is no convenient way to generate a list of all available targets. `HOST ...' Configure GDB to run on the specified HOST. There is no convenient way to generate a list of all available hosts. `configure' accepts other options, for compatibility with configuring other GNU tools recursively; but these are the only options that affect GDB or its supporting libraries.