mingw/info/gdbint/Host-Definition.html

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  19 <h2 class="chapter">Host Definition</h2>
  20
  21    <p>With the advent of Autoconf, it's rarely necessary to have host
  22 definition machinery anymore.  The following information is provided,
  23 mainly, as an historical reference.
  24
  25 <h3 class="section">Adding a New Host</h3>
  26
  27    GDB's host configuration support normally happens via Autoconf.
  28 New host-specific definitions should not be needed.  Older hosts
  29 GDB still use the host-specific definitions and files listed
  30 below, but these mostly exist for historical reasons, and will
  31 eventually disappear.
  32
  33      <dl>
  34 <dt><code>gdb/config/</code><var>arch</var><code>/</code><var>xyz</var><code>.mh</code>
  35      <dd>This file once contained both host and native configuration information
  36 (see <a href="Native-Debugging.html#Native%20Debugging">Native Debugging</a>) for the machine <var>xyz</var>.  The host
  37 configuration information is now handed by Autoconf.
  38
  39      <p>Host configuration information included a definition of
  40 <code>XM_FILE=xm-</code><var>xyz</var><code>.h</code> and possibly definitions for <code>CC</code>,
  41 <code>SYSV_DEFINE</code>, <code>XM_CFLAGS</code>, <code>XM_ADD_FILES</code>,
  42 <code>XM_CLIBS</code>, <code>XM_CDEPS</code>, etc.; see <code>Makefile.in</code>.
  43
  44      <p>New host only configurations do not need this file.
  45
  46      <br><dt><code>gdb/config/</code><var>arch</var><code>/xm-</code><var>xyz</var><code>.h</code>
  47      <dd>This file once contained definitions and includes required when hosting
  48 gdb on machine <var>xyz</var>.  Those definitions and includes are now
  49 handled by Autoconf.
  50
  51      <p>New host and native configurations do not need this file.
  52
  53      <p><em>Maintainer's note: Some hosts continue to use the </em><code>xm-xyz.h</code><em>
  54 file to define the macros </em><var>HOST_FLOAT_FORMAT</var><em>,
  55 </em><var>HOST_DOUBLE_FORMAT</var><em> and </em><var>HOST_LONG_DOUBLE_FORMAT</var><em>.  That code
  56 also needs to be replaced with either an Autoconf or run-time test.</em>
  57
  58    </dl>
  59
  60 <h4 class="subheading">Generic Host Support Files</h4>
  61
  62    <p>There are some "generic" versions of routines that can be used by
  63 various systems.  These can be customized in various ways by macros
  64 defined in your <code>xm-</code><var>xyz</var><code>.h</code> file.  If these routines work for
  65 the <var>xyz</var> host, you can just include the generic file's name (with
  66 <code>.o</code>, not <code>.c</code>) in <code>XDEPFILES</code>.
  67
  68    <p>Otherwise, if your machine needs custom support routines, you will need
  69 to write routines that perform the same functions as the generic file.
  70 Put them into <code></code><var>xyz</var><code>-xdep.c</code>, and put <code></code><var>xyz</var><code>-xdep.o</code>
  71 into <code>XDEPFILES</code>.
  72
  73      <dl>
  74 <dt><code>ser-unix.c</code>
  75      <dd>This contains serial line support for Unix systems.  This is always
  76 included, via the makefile variable <code>SER_HARDWIRE</code>; override this
  77 variable in the <code>.mh</code> file to avoid it.
  78
  79      <br><dt><code>ser-go32.c</code>
  80      <dd>This contains serial line support for 32-bit programs running under DOS,
  81 using the DJGPP (a.k.a. GO32) execution environment.
  82
  83      <br><dt><code>ser-tcp.c</code>
  84      <dd>This contains generic TCP support using sockets.
  85 </dl>
  86
  87 <h3 class="section">Host Conditionals</h3>
  88
  89    <p>When GDB is configured and compiled, various macros are
  90 defined or left undefined, to control compilation based on the
  91 attributes of the host system.  These macros and their meanings (or if
  92 the meaning is not documented here, then one of the source files where
  93 they are used is indicated) are:
  94
  95      <dl>
  96 <dt><code>GDBINIT_FILENAME</code>
  97      <dd>The default name of GDB's initialization file (normally
  98 <code>.gdbinit</code>).
  99
 100      <br><dt><code>NO_STD_REGS</code>
 101      <dd>This macro is deprecated.
 102
 103      <br><dt><code>NO_SYS_FILE</code>
 104      <dd>Define this if your system does not have a <code>&lt;sys/file.h&gt;</code>.
 105
 106      <br><dt><code>SIGWINCH_HANDLER</code>
 107      <dd>If your host defines <code>SIGWINCH</code>, you can define this to be the name
 108 of a function to be called if <code>SIGWINCH</code> is received.
 109
 110      <br><dt><code>SIGWINCH_HANDLER_BODY</code>
 111      <dd>Define this to expand into code that will define the function named by
 112 the expansion of <code>SIGWINCH_HANDLER</code>.
 113
 114      <br><dt><code>ALIGN_STACK_ON_STARTUP</code>
 115      <dd>Define this if your system is of a sort that will crash in
 116 <code>tgetent</code> if the stack happens not to be longword-aligned when
 117 <code>main</code> is called.  This is a rare situation, but is known to occur
 118 on several different types of systems.
 119
 120      <br><dt><code>CRLF_SOURCE_FILES</code>
 121      <dd>Define this if host files use <code>\r\n</code> rather than <code>\n</code> as a
 122 line terminator.  This will cause source file listings to omit <code>\r</code>
 123 characters when printing and it will allow <code>\r\n</code> line endings of files
 124 which are "sourced" by gdb.  It must be possible to open files in binary
 125 mode using <code>O_BINARY</code> or, for fopen, <code>"rb"</code>.
 126
 127      <br><dt><code>DEFAULT_PROMPT</code>
 128      <dd>The default value of the prompt string (normally <code>"(gdb) "</code>).
 129
 130      <br><dt><code>DEV_TTY</code>
 131      <dd>The name of the generic TTY device, defaults to <code>"/dev/tty"</code>.
 132
 133      <br><dt><code>FCLOSE_PROVIDED</code>
 134      <dd>Define this if the system declares <code>fclose</code> in the headers included
 135 in <code>defs.h</code>.  This isn't needed unless your compiler is unusually
 136 anal.
 137
 138      <br><dt><code>FOPEN_RB</code>
 139      <dd>Define this if binary files are opened the same way as text files.
 140
 141      <br><dt><code>GETENV_PROVIDED</code>
 142      <dd>Define this if the system declares <code>getenv</code> in its headers included
 143 in <code>defs.h</code>.  This isn't needed unless your compiler is unusually
 144 anal.
 145
 146      <br><dt><code>HAVE_MMAP</code>
 147      <dd>In some cases, use the system call <code>mmap</code> for reading symbol
 148 tables.  For some machines this allows for sharing and quick updates.
 149
 150      <br><dt><code>HAVE_TERMIO</code>
 151      <dd>Define this if the host system has <code>termio.h</code>.
 152
 153      <br><dt><code>INT_MAX</code>
 154      <dd><dt><code>INT_MIN</code>
 155      <dd><dt><code>LONG_MAX</code>
 156      <dd><dt><code>UINT_MAX</code>
 157      <dd><dt><code>ULONG_MAX</code>
 158      <dd>Values for host-side constants.
 159
 160      <br><dt><code>ISATTY</code>
 161      <dd>Substitute for isatty, if not available.
 162
 163      <br><dt><code>LONGEST</code>
 164      <dd>This is the longest integer type available on the host.  If not defined,
 165 it will default to <code>long long</code> or <code>long</code>, depending on
 166 <code>CC_HAS_LONG_LONG</code>.
 167
 168      <br><dt><code>CC_HAS_LONG_LONG</code>
 169      <dd>Define this if the host C compiler supports <code>long long</code>.  This is set
 170 by the <code>configure</code> script.
 171
 172      <br><dt><code>PRINTF_HAS_LONG_LONG</code>
 173      <dd>Define this if the host can handle printing of long long integers via
 174 the printf format conversion specifier <code>ll</code>.  This is set by the
 175 <code>configure</code> script.
 176
 177      <br><dt><code>HAVE_LONG_DOUBLE</code>
 178      <dd>Define this if the host C compiler supports <code>long double</code>.  This is
 179 set by the <code>configure</code> script.
 180
 181      <br><dt><code>PRINTF_HAS_LONG_DOUBLE</code>
 182      <dd>Define this if the host can handle printing of long double float-point
 183 numbers via the printf format conversion specifier <code>Lg</code>.  This is
 184 set by the <code>configure</code> script.
 185
 186      <br><dt><code>SCANF_HAS_LONG_DOUBLE</code>
 187      <dd>Define this if the host can handle the parsing of long double
 188 float-point numbers via the scanf format conversion specifier
 189 <code>Lg</code>.  This is set by the <code>configure</code> script.
 190
 191      <br><dt><code>LSEEK_NOT_LINEAR</code>
 192      <dd>Define this if <code>lseek (n)</code> does not necessarily move to byte number
 193 <code>n</code> in the file.  This is only used when reading source files.  It
 194 is normally faster to define <code>CRLF_SOURCE_FILES</code> when possible.
 195
 196      <br><dt><code>L_SET</code>
 197      <dd>This macro is used as the argument to <code>lseek</code> (or, most commonly,
 198 <code>bfd_seek</code>).  FIXME, should be replaced by SEEK_SET instead,
 199 which is the POSIX equivalent.
 200
 201      <br><dt><code>MMAP_BASE_ADDRESS</code>
 202      <dd>When using HAVE_MMAP, the first mapping should go at this address.
 203
 204      <br><dt><code>MMAP_INCREMENT</code>
 205      <dd>when using HAVE_MMAP, this is the increment between mappings.
 206
 207      <br><dt><code>NORETURN</code>
 208      <dd>If defined, this should be one or more tokens, such as <code>volatile</code>,
 209 that can be used in both the declaration and definition of functions to
 210 indicate that they never return.  The default is already set correctly
 211 if compiling with GCC.  This will almost never need to be defined.
 212
 213      <br><dt><code>ATTR_NORETURN</code>
 214      <dd>If defined, this should be one or more tokens, such as
 215 <code>__attribute__ ((noreturn))</code>, that can be used in the declarations
 216 of functions to indicate that they never return.  The default is already
 217 set correctly if compiling with GCC.  This will almost never need to be
 218 defined.
 219
 220      <br><dt><code>USE_GENERIC_DUMMY_FRAMES</code>
 221      <dd>Define this to 1 if the target is using the generic inferior function
 222 call code.  See <code>blockframe.c</code> for more information.
 223
 224      <br><dt><code>USE_MMALLOC</code>
 225      <dd>GDB will use the <code>mmalloc</code> library for memory allocation
 226 for symbol reading if this symbol is defined.  Be careful defining it
 227 since there are systems on which <code>mmalloc</code> does not work for some
 228 reason.  One example is the DECstation, where its RPC library can't
 229 cope with our redefinition of <code>malloc</code> to call <code>mmalloc</code>.
 230 When defining <code>USE_MMALLOC</code>, you will also have to set
 231 <code>MMALLOC</code> in the Makefile, to point to the <code>mmalloc</code> library.  This
 232 define is set when you configure with <code>--with-mmalloc</code>.
 233
 234      <br><dt><code>NO_MMCHECK</code>
 235      <dd>Define this if you are using <code>mmalloc</code>, but don't want the overhead
 236 of checking the heap with <code>mmcheck</code>.  Note that on some systems,
 237 the C runtime makes calls to <code>malloc</code> prior to calling <code>main</code>, and if
 238 <code>free</code> is ever called with these pointers after calling
 239 <code>mmcheck</code> to enable checking, a memory corruption abort is certain
 240 to occur.  These systems can still use <code>mmalloc</code>, but must define
 241 <code>NO_MMCHECK</code>.
 242
 243      <br><dt><code>MMCHECK_FORCE</code>
 244      <dd>Define this to 1 if the C runtime allocates memory prior to
 245 <code>mmcheck</code> being called, but that memory is never freed so we don't
 246 have to worry about it triggering a memory corruption abort.  The
 247 default is 0, which means that <code>mmcheck</code> will only install the heap
 248 checking functions if there has not yet been any memory allocation
 249 calls, and if it fails to install the functions, GDB will issue a
 250 warning.  This is currently defined if you configure using
 251 <code>--with-mmalloc</code>.
 252
 253      <br><dt><code>NO_SIGINTERRUPT</code>
 254      <dd>Define this to indicate that <code>siginterrupt</code> is not available.
 255
 256      <br><dt><code>SEEK_CUR</code>
 257      <dd><dt><code>SEEK_SET</code>
 258      <dd>Define these to appropriate value for the system <code>lseek</code>, if not already
 259 defined.
 260
 261      <br><dt><code>STOP_SIGNAL</code>
 262      <dd>This is the signal for stopping GDB.  Defaults to
 263 <code>SIGTSTP</code>.  (Only redefined for the Convex.)
 264
 265      <br><dt><code>USE_O_NOCTTY</code>
 266      <dd>Define this if the interior's tty should be opened with the <code>O_NOCTTY</code>
 267 flag.  (FIXME: This should be a native-only flag, but <code>inflow.c</code> is
 268 always linked in.)
 269
 270      <br><dt><code>USG</code>
 271      <dd>Means that System V (prior to SVR4) include files are in use.  (FIXME:
 272 This symbol is abused in <code>infrun.c</code>, <code>regex.c</code>,
 273 <code>remote-nindy.c</code>, and <code>utils.c</code> for other things, at the
 274 moment.)
 275
 276      <br><dt><code>lint</code>
 277      <dd>Define this to help placate <code>lint</code> in some situations.
 278
 279      <br><dt><code>volatile</code>
 280      <dd>Define this to override the defaults of <code>__volatile__</code> or
 281 <code>/**/</code>.
 282 </dl>
 283
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