131 lines
6.0 KiB
Plaintext
131 lines
6.0 KiB
Plaintext
@c Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
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@c 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
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@c This is part of the GCC manual.
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@c For copying conditions, see the file gcc.texi.
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@node Host Config
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@chapter Host Configuration Headers
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@cindex configuration file
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@cindex @file{xm-@var{machine}.h}
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Host configuration headers contain macro definitions that describe the
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machine and system on which the compiler is running. They are usually
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unnecessary. Most of the things GCC needs to know about the host
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system can be deduced by the @command{configure} script.
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If your host does need a special configuration header, it should be
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named @file{xm-@var{machine}.h}, where @var{machine} is a short mnemonic
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for the machine. Here are some macros which this header can define.
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@ftable @code
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@item VMS
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Define this macro if the host system is VMS@.
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@item FATAL_EXIT_CODE
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A C expression for the status code to be returned when the compiler
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exits after serious errors. The default is the system-provided macro
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@samp{EXIT_FAILURE}, or @samp{1} if the system doesn't define that
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macro. Define this macro only if these defaults are incorrect.
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@item SUCCESS_EXIT_CODE
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A C expression for the status code to be returned when the compiler
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exits without serious errors. (Warnings are not serious errors.) The
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default is the system-provided macro @samp{EXIT_SUCCESS}, or @samp{0} if
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the system doesn't define that macro. Define this macro only if these
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defaults are incorrect.
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@item USE_C_ALLOCA
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Define this macro if GCC should use the C implementation of @code{alloca}
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provided by @file{libiberty.a}. This only affects how some parts of the
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compiler itself allocate memory. It does not change code generation.
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When GCC is built with a compiler other than itself, the C @code{alloca}
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is always used. This is because most other implementations have serious
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bugs. You should define this macro only on a system where no
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stack-based @code{alloca} can possibly work. For instance, if a system
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has a small limit on the size of the stack, GCC's builtin @code{alloca}
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will not work reliably.
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@item HAVE_DOS_BASED_FILE_SYSTEM
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Define this macro if the host file system obeys the semantics defined by
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MS-DOS instead of Unix. DOS file systems are case insensitive, file
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specifications may begin with a drive letter, and both forward slash and
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backslash (@samp{/} and @samp{\}) are directory separators. If you
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define this macro, you probably need to define the next three macros too.
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@item PATH_SEPARATOR
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If defined, this macro should expand to a character constant specifying
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the separator for elements of search paths. The default value is a
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colon (@samp{:}). DOS-based systems usually use semicolon (@samp{;}).
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@item DIR_SEPARATOR
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@itemx DIR_SEPARATOR_2
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If defined, these macros expand to character constants specifying
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separators for directory names within a file specification. They are
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used somewhat inconsistently throughout the compiler. If your system
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behaves like Unix (only forward slash separates pathnames), define
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neither of them. If your system behaves like DOS (both forward and
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backward slash can be used), define @code{DIR_SEPARATOR} to @samp{/}
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and @code{DIR_SEPARATOR_2} to @samp{\}.
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@item HOST_OBJECT_SUFFIX
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Define this macro to be a C string representing the suffix for object
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files on your host machine. If you do not define this macro, GCC will
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use @samp{.o} as the suffix for object files.
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@item HOST_EXECUTABLE_SUFFIX
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Define this macro to be a C string representing the suffix for
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executable files on your host machine. If you do not define this macro,
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GCC will use the null string as the suffix for executable files.
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@item HOST_BIT_BUCKET
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A pathname defined by the host operating system, which can be opened as
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a file and written to, but all the information written is discarded.
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This is commonly known as a @dfn{bit bucket} or @dfn{null device}. If
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you do not define this macro, GCC will use @samp{/dev/null} as the bit
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bucket. If the host does not support a bit bucket, define this macro to
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an invalid filename.
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@item COLLECT2_HOST_INITIALIZATION
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If defined, a C statement (sans semicolon) that performs host-dependent
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initialization when @code{collect2} is being initialized.
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@item GCC_DRIVER_HOST_INITIALIZATION
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If defined, a C statement (sans semicolon) that performs host-dependent
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initialization when a compilation driver is being initialized.
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@item UPDATE_PATH_HOST_CANONICALIZE (@var{path})
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If defined, a C statement (sans semicolon) that performs host-dependent
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canonicalization when a path used in a compilation driver or
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preprocessor is canonicalized. @var{path} is a malloc-ed path to be
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canonicalized. If the C statement does canonicalize @var{path} into a
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different buffer, the old path should be freed and the new buffer should
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have been allocated with malloc.
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@item DUMPFILE_FORMAT
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Define this macro to be a C string representing the format to use for
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constructing the index part of debugging dump file names. The resultant
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string must fit in fifteen bytes. The full filename will be the
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concatenation of: the prefix of the assembler file name, the string
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resulting from applying this format to an index number, and a string
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unique to each dump file kind, e.g. @samp{rtl}.
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If you do not define this macro, GCC will use @samp{.%02d.}. You should
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define this macro if using the default will create an invalid file name.
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@item SMALL_ARG_MAX
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Define this macro if the host system has a small limit on the total
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size of an argument vector. This causes the driver to take more care
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not to pass unnecessary arguments to subprocesses.
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@end ftable
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In addition, if @command{configure} generates an incorrect definition of
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any of the macros in @file{auto-host.h}, you can override that
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definition in a host configuration header. If you need to do this,
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first see if it is possible to fix @command{configure}.
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If you need to define only a few of these macros, and they have simple
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definitions, consider using the @code{xm_defines} variable in your
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@file{config.gcc} entry instead of creating a host configuration header.
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@xref{System Config}.
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