| @c Copyright (C) 1988-2021 Free Software Foundation, Inc. |
| @c This is part of the GCC manual. |
| @c For copying conditions, see the file gccint.texi. |
| |
| @node Host Config |
| @chapter Host Configuration |
| @cindex host configuration |
| |
| Most details about the machine and system on which the compiler is |
| actually running are detected by the @command{configure} script. Some |
| things are impossible for @command{configure} to detect; these are |
| described in two ways, either by macros defined in a file named |
| @file{xm-@var{machine}.h} or by hook functions in the file specified |
| by the @var{out_host_hook_obj} variable in @file{config.gcc}. (The |
| intention is that very few hosts will need a header file but nearly |
| every fully supported host will need to override some hooks.) |
| |
| If you need to define only a few macros, and they have simple |
| definitions, consider using the @code{xm_defines} variable in your |
| @file{config.gcc} entry instead of creating a host configuration |
| header. @xref{System Config}. |
| |
| @menu |
| * Host Common:: Things every host probably needs implemented. |
| * Filesystem:: Your host cannot have the letter `a' in filenames? |
| * Host Misc:: Rare configuration options for hosts. |
| @end menu |
| |
| @node Host Common |
| @section Host Common |
| @cindex host hooks |
| @cindex host functions |
| |
| Some things are just not portable, even between similar operating systems, |
| and are too difficult for autoconf to detect. They get implemented using |
| hook functions in the file specified by the @var{host_hook_obj} |
| variable in @file{config.gcc}. |
| |
| @deftypefn {Host Hook} void HOST_HOOKS_EXTRA_SIGNALS (void) |
| This host hook is used to set up handling for extra signals. The most |
| common thing to do in this hook is to detect stack overflow. |
| @end deftypefn |
| |
| @deftypefn {Host Hook} {void *} HOST_HOOKS_GT_PCH_GET_ADDRESS (size_t @ |
| @var{size}, int @var{fd}) |
| This host hook returns the address of some space that is likely to be |
| free in some subsequent invocation of the compiler. We intend to load |
| the PCH data at this address such that the data need not be relocated. |
| The area should be able to hold @var{size} bytes. If the host uses |
| @code{mmap}, @var{fd} is an open file descriptor that can be used for |
| probing. |
| @end deftypefn |
| |
| @deftypefn {Host Hook} int HOST_HOOKS_GT_PCH_USE_ADDRESS (void * @var{address}, @ |
| size_t @var{size}, int @var{fd}, size_t @var{offset}) |
| This host hook is called when a PCH file is about to be loaded. |
| We want to load @var{size} bytes from @var{fd} at @var{offset} |
| into memory at @var{address}. The given address will be the result of |
| a previous invocation of @code{HOST_HOOKS_GT_PCH_GET_ADDRESS}. |
| Return @minus{}1 if we couldn't allocate @var{size} bytes at @var{address}. |
| Return 0 if the memory is allocated but the data is not loaded. Return 1 |
| if the hook has performed everything. |
| |
| If the implementation uses reserved address space, free any reserved |
| space beyond @var{size}, regardless of the return value. If no PCH will |
| be loaded, this hook may be called with @var{size} zero, in which case |
| all reserved address space should be freed. |
| |
| Do not try to handle values of @var{address} that could not have been |
| returned by this executable; just return @minus{}1. Such values usually |
| indicate an out-of-date PCH file (built by some other GCC executable), |
| and such a PCH file won't work. |
| @end deftypefn |
| |
| @deftypefn {Host Hook} size_t HOST_HOOKS_GT_PCH_ALLOC_GRANULARITY (void); |
| This host hook returns the alignment required for allocating virtual |
| memory. Usually this is the same as getpagesize, but on some hosts the |
| alignment for reserving memory differs from the pagesize for committing |
| memory. |
| @end deftypefn |
| |
| @node Filesystem |
| @section Host Filesystem |
| @cindex configuration file |
| @cindex @file{xm-@var{machine}.h} |
| |
| GCC needs to know a number of things about the semantics of the host |
| machine's filesystem. Filesystems with Unix and MS-DOS semantics are |
| automatically detected. For other systems, you can define the |
| following macros in @file{xm-@var{machine}.h}. |
| |
| @ftable @code |
| @item HAVE_DOS_BASED_FILE_SYSTEM |
| This macro is automatically defined by @file{system.h} if the host |
| file system obeys the semantics defined by MS-DOS instead of Unix. |
| DOS file systems are case insensitive, file specifications may begin |
| with a drive letter, and both forward slash and backslash (@samp{/} |
| and @samp{\}) are directory separators. |
| |
| @item DIR_SEPARATOR |
| @itemx DIR_SEPARATOR_2 |
| If defined, these macros expand to character constants specifying |
| separators for directory names within a file specification. |
| @file{system.h} will automatically give them appropriate values on |
| Unix and MS-DOS file systems. If your file system is neither of |
| these, define one or both appropriately in @file{xm-@var{machine}.h}. |
| |
| However, operating systems like VMS, where constructing a pathname is |
| more complicated than just stringing together directory names |
| separated by a special character, should not define either of these |
| macros. |
| |
| @item PATH_SEPARATOR |
| If defined, this macro should expand to a character constant |
| specifying the separator for elements of search paths. The default |
| value is a colon (@samp{:}). DOS-based systems usually, but not |
| always, use semicolon (@samp{;}). |
| |
| @item VMS |
| Define this macro if the host system is VMS@. |
| |
| @item HOST_OBJECT_SUFFIX |
| Define this macro to be a C string representing the suffix for object |
| files on your host machine. If you do not define this macro, GCC will |
| use @samp{.o} as the suffix for object files. |
| |
| @item HOST_EXECUTABLE_SUFFIX |
| Define this macro to be a C string representing the suffix for |
| executable files on your host machine. If you do not define this macro, |
| GCC will use the null string as the suffix for executable files. |
| |
| @item HOST_BIT_BUCKET |
| A pathname defined by the host operating system, which can be opened as |
| a file and written to, but all the information written is discarded. |
| This is commonly known as a @dfn{bit bucket} or @dfn{null device}. If |
| you do not define this macro, GCC will use @samp{/dev/null} as the bit |
| bucket. If the host does not support a bit bucket, define this macro to |
| an invalid filename. |
| |
| @item UPDATE_PATH_HOST_CANONICALIZE (@var{path}) |
| If defined, a C statement (sans semicolon) that performs host-dependent |
| canonicalization when a path used in a compilation driver or |
| preprocessor is canonicalized. @var{path} is a malloc-ed path to be |
| canonicalized. If the C statement does canonicalize @var{path} into a |
| different buffer, the old path should be freed and the new buffer should |
| have been allocated with malloc. |
| |
| @item DUMPFILE_FORMAT |
| Define this macro to be a C string representing the format to use for |
| constructing the index part of debugging dump file names. The resultant |
| string must fit in fifteen bytes. The full filename will be the |
| concatenation of: the prefix of the assembler file name, the string |
| resulting from applying this format to an index number, and a string |
| unique to each dump file kind, e.g.@: @samp{rtl}. |
| |
| If you do not define this macro, GCC will use @samp{.%02d.}. You should |
| define this macro if using the default will create an invalid file name. |
| |
| @item DELETE_IF_ORDINARY |
| Define this macro to be a C statement (sans semicolon) that performs |
| host-dependent removal of ordinary temp files in the compilation driver. |
| |
| If you do not define this macro, GCC will use the default version. You |
| should define this macro if the default version does not reliably remove |
| the temp file as, for example, on VMS which allows multiple versions |
| of a file. |
| |
| @item HOST_LACKS_INODE_NUMBERS |
| Define this macro if the host filesystem does not report meaningful inode |
| numbers in struct stat. |
| @end ftable |
| |
| @node Host Misc |
| @section Host Misc |
| @cindex configuration file |
| @cindex @file{xm-@var{machine}.h} |
| |
| @ftable @code |
| @item FATAL_EXIT_CODE |
| A C expression for the status code to be returned when the compiler |
| exits after serious errors. The default is the system-provided macro |
| @samp{EXIT_FAILURE}, or @samp{1} if the system doesn't define that |
| macro. Define this macro only if these defaults are incorrect. |
| |
| @item SUCCESS_EXIT_CODE |
| A C expression for the status code to be returned when the compiler |
| exits without serious errors. (Warnings are not serious errors.) The |
| default is the system-provided macro @samp{EXIT_SUCCESS}, or @samp{0} if |
| the system doesn't define that macro. Define this macro only if these |
| defaults are incorrect. |
| |
| @item USE_C_ALLOCA |
| Define this macro if GCC should use the C implementation of @code{alloca} |
| provided by @file{libiberty.a}. This only affects how some parts of the |
| compiler itself allocate memory. It does not change code generation. |
| |
| When GCC is built with a compiler other than itself, the C @code{alloca} |
| is always used. This is because most other implementations have serious |
| bugs. You should define this macro only on a system where no |
| stack-based @code{alloca} can possibly work. For instance, if a system |
| has a small limit on the size of the stack, GCC's builtin @code{alloca} |
| will not work reliably. |
| |
| @item COLLECT2_HOST_INITIALIZATION |
| If defined, a C statement (sans semicolon) that performs host-dependent |
| initialization when @code{collect2} is being initialized. |
| |
| @item GCC_DRIVER_HOST_INITIALIZATION |
| If defined, a C statement (sans semicolon) that performs host-dependent |
| initialization when a compilation driver is being initialized. |
| |
| @item HOST_LONG_LONG_FORMAT |
| If defined, the string used to indicate an argument of type @code{long |
| long} to functions like @code{printf}. The default value is |
| @code{"ll"}. |
| |
| @item HOST_LONG_FORMAT |
| If defined, the string used to indicate an argument of type @code{long} |
| to functions like @code{printf}. The default value is @code{"l"}. |
| |
| @item HOST_PTR_PRINTF |
| If defined, the string used to indicate an argument of type @code{void *} |
| to functions like @code{printf}. The default value is @code{"%p"}. |
| @end ftable |
| |
| In addition, if @command{configure} generates an incorrect definition of |
| any of the macros in @file{auto-host.h}, you can override that |
| definition in a host configuration header. If you need to do this, |
| first see if it is possible to fix @command{configure}. |