gdbint.info: Host Definition

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Host Definition

With the advent of Autoconf, it's rarely necessary to have host
definition machinery anymore.  The following information is provided,
mainly, as an historical reference.

Adding a New Host

GDB's host configuration support normally happens via Autoconf.  New
host-specific definitions should not be needed.  Older hosts GDB still
use the host-specific definitions and files listed below, but these
mostly exist for historical reasons, and will eventually disappear.
`gdb/config/ARCH/XYZ.mh'
     This file once contained both host and native configuration
     information (*note Native Debugging::) for the machine XYZ.  The
     host configuration information is now handed by Autoconf.
     Host configuration information included a definition of
     `XM_FILE=xm-XYZ.h' and possibly definitions for `CC',
     `SYSV_DEFINE', `XM_CFLAGS', `XM_ADD_FILES', `XM_CLIBS',
     `XM_CDEPS', etc.; see `Makefile.in'.
     New host only configurations do not need this file.
`gdb/config/ARCH/xm-XYZ.h'
     This file once contained definitions and includes required when
     hosting gdb on machine XYZ.  Those definitions and includes are now
     handled by Autoconf.
     New host and native configurations do not need this file.
     _Maintainer's note: Some hosts continue to use the `xm-xyz.h' file
     to define the macros HOST_FLOAT_FORMAT, HOST_DOUBLE_FORMAT and
     HOST_LONG_DOUBLE_FORMAT.  That code also needs to be replaced with
     either an Autoconf or run-time test._

Generic Host Support Files

There are some "generic" versions of routines that can be used by
various systems.  These can be customized in various ways by macros
defined in your `xm-XYZ.h' file.  If these routines work for the XYZ
host, you can just include the generic file's name (with `.o', not
`.c') in `XDEPFILES'.
   Otherwise, if your machine needs custom support routines, you will
need to write routines that perform the same functions as the generic
file.  Put them into `XYZ-xdep.c', and put `XYZ-xdep.o' into
`XDEPFILES'.
`ser-unix.c'
     This contains serial line support for Unix systems.  This is always
     included, via the makefile variable `SER_HARDWIRE'; override this
     variable in the `.mh' file to avoid it.
`ser-go32.c'
     This contains serial line support for 32-bit programs running
     under DOS, using the DJGPP (a.k.a. GO32) execution environment.
`ser-tcp.c'
     This contains generic TCP support using sockets.

Host Conditionals

When GDB is configured and compiled, various macros are defined or left
undefined, to control compilation based on the attributes of the host
system.  These macros and their meanings (or if the meaning is not
documented here, then one of the source files where they are used is
indicated) are:
`GDBINIT_FILENAME'
     The default name of GDB's initialization file (normally
     `.gdbinit').
`NO_STD_REGS'
     This macro is deprecated.
`NO_SYS_FILE'
     Define this if your system does not have a `<sys/file.h>'.
`SIGWINCH_HANDLER'
     If your host defines `SIGWINCH', you can define this to be the name
     of a function to be called if `SIGWINCH' is received.
`SIGWINCH_HANDLER_BODY'
     Define this to expand into code that will define the function
     named by the expansion of `SIGWINCH_HANDLER'.
`ALIGN_STACK_ON_STARTUP'
     Define this if your system is of a sort that will crash in
     `tgetent' if the stack happens not to be longword-aligned when
     `main' is called.  This is a rare situation, but is known to occur
     on several different types of systems.
`CRLF_SOURCE_FILES'
     Define this if host files use `\r\n' rather than `\n' as a line
     terminator.  This will cause source file listings to omit `\r'
     characters when printing and it will allow `\r\n' line endings of
     files which are "sourced" by gdb.  It must be possible to open
     files in binary mode using `O_BINARY' or, for fopen, `"rb"'.
`DEFAULT_PROMPT'
     The default value of the prompt string (normally `"(gdb) "').
`DEV_TTY'
     The name of the generic TTY device, defaults to `"/dev/tty"'.
`FCLOSE_PROVIDED'
     Define this if the system declares `fclose' in the headers included
     in `defs.h'.  This isn't needed unless your compiler is unusually
     anal.
`FOPEN_RB'
     Define this if binary files are opened the same way as text files.
`GETENV_PROVIDED'
     Define this if the system declares `getenv' in its headers included
     in `defs.h'.  This isn't needed unless your compiler is unusually
     anal.
`HAVE_MMAP'
     In some cases, use the system call `mmap' for reading symbol
     tables.  For some machines this allows for sharing and quick
     updates.
`HAVE_TERMIO'
     Define this if the host system has `termio.h'.
`INT_MAX'
`INT_MIN'
`LONG_MAX'
`UINT_MAX'
`ULONG_MAX'
     Values for host-side constants.
`ISATTY'
     Substitute for isatty, if not available.
`LONGEST'
     This is the longest integer type available on the host.  If not
     defined, it will default to `long long' or `long', depending on
     `CC_HAS_LONG_LONG'.
`CC_HAS_LONG_LONG'
     Define this if the host C compiler supports `long long'.  This is
     set by the `configure' script.
`PRINTF_HAS_LONG_LONG'
     Define this if the host can handle printing of long long integers
     via the printf format conversion specifier `ll'.  This is set by
     the `configure' script.
`HAVE_LONG_DOUBLE'
     Define this if the host C compiler supports `long double'.  This is
     set by the `configure' script.
`PRINTF_HAS_LONG_DOUBLE'
     Define this if the host can handle printing of long double
     float-point numbers via the printf format conversion specifier
     `Lg'.  This is set by the `configure' script.
`SCANF_HAS_LONG_DOUBLE'
     Define this if the host can handle the parsing of long double
     float-point numbers via the scanf format conversion specifier
     `Lg'.  This is set by the `configure' script.
`LSEEK_NOT_LINEAR'
     Define this if `lseek (n)' does not necessarily move to byte number
     `n' in the file.  This is only used when reading source files.  It
     is normally faster to define `CRLF_SOURCE_FILES' when possible.
`L_SET'
     This macro is used as the argument to `lseek' (or, most commonly,
     `bfd_seek').  FIXME, should be replaced by SEEK_SET instead, which
     is the POSIX equivalent.
`NORETURN'
     If defined, this should be one or more tokens, such as `volatile',
     that can be used in both the declaration and definition of
     functions to indicate that they never return.  The default is
     already set correctly if compiling with GCC.  This will almost
     never need to be defined.
`ATTR_NORETURN'
     If defined, this should be one or more tokens, such as
     `__attribute__ ((noreturn))', that can be used in the declarations
     of functions to indicate that they never return.  The default is
     already set correctly if compiling with GCC.  This will almost
     never need to be defined.
`SEEK_CUR'
`SEEK_SET'
     Define these to appropriate value for the system `lseek', if not
     already defined.
`STOP_SIGNAL'
     This is the signal for stopping GDB.  Defaults to `SIGTSTP'.
     (Only redefined for the Convex.)
`USE_O_NOCTTY'
     Define this if the interior's tty should be opened with the
     `O_NOCTTY' flag.  (FIXME: This should be a native-only flag, but
     `inflow.c' is always linked in.)
`USG'
     Means that System V (prior to SVR4) include files are in use.
     (FIXME: This symbol is abused in `infrun.c', `regex.c', and
     `utils.c' for other things, at the moment.)
`lint'
     Define this to help placate `lint' in some situations.
`volatile'
     Define this to override the defaults of `__volatile__' or `/**/'.