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Diffstat (limited to 'gcc/doc/fragments.texi')
| -rw-r--r-- | gcc/doc/fragments.texi | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/gcc/doc/fragments.texi b/gcc/doc/fragments.texi index f53df29603e..28cef689f15 100644 --- a/gcc/doc/fragments.texi +++ b/gcc/doc/fragments.texi @@ -93,6 +93,12 @@ Write one element in @code{MULTILIB_DIRNAMES} for each element in default value will be @code{MULTILIB_OPTIONS}, with all slashes treated as spaces. +@code{MULTILIB_DIRNAMES} describes the multilib directories using GCC +conventions and is applied to directories that are part of the GCC +installation. When multilib-enabled, the compiler will add a +subdirectory of the form @var{prefix}/@var{multilib} before each +directory in the search path for libraries and crt files. + For example, if @code{MULTILIB_OPTIONS} is set to @samp{m68000/m68020 msoft-float}, then the default value of @code{MULTILIB_DIRNAMES} is @samp{m68000 m68020 msoft-float}. You may specify a different value if @@ -152,6 +158,60 @@ compiler. In that case, set @code{MULTILIB_EXTRA_OPTS} to be the list of options to be used for all builds. If you set this, you should probably set @code{CRTSTUFF_T_CFLAGS} to a dash followed by it. +@findex MULTILIB_OSDIRNAMES +@item MULTILIB_OSDIRNAMES +If @code{MULTILIB_OPTIONS} is used, this variable specifies +a list of subdirectory names, that are used to modify the search +path depending on the chosen multilib. Unlike @code{MULTILIB_DIRNAMES}, +@code{MULTILIB_OSDIRNAMES} describes the multilib directories using +operating systems conventions, and is applied to the directories such as +@code{lib} or those in the @env{LIBRARY_PATH} environment variable. +The format is either the same as of +@code{MULTILIB_DIRNAMES}, or a set of mappings. When it is the same +as @code{MULTILIB_DIRNAMES}, it describes the multilib directories +using operating system conventions, rather than GCC conventions. When it is a set +of mappings of the form @var{gccdir}=@var{osdir}, the left side gives +the GCC convention and the right gives the equivalent OS defined +location. If the @var{osdir} part begins with a @samp{!}, +GCC will not search in the non-multilib directory and use +exclusively the multilib directory. Otherwise, the compiler will +examine the search path for libraries and crt files twice; the first +time it will add @var{multilib} to each directory in the search path, +the second it will not. + +For configurations that support both multilib and multiarch, +@code{MULTILIB_OSDIRNAMES} also encodes the multiarch name, thus +subsuming @code{MULTIARCH_DIRNAME}. The multiarch name is appended to +each directory name, separated by a colon (e.g. +@samp{../lib32:i386-linux-gnu}). + +Each multiarch subdirectory will be searched before the corresponding OS +multilib directory, for example @samp{/lib/i386-linux-gnu} before +@samp{/lib/../lib32}. The multiarch name will also be used to modify the +system header search path, as explained for @code{MULTIARCH_DIRNAME}. + +@findex MULTIARCH_DIRNAME +@item MULTIARCH_DIRNAME +This variable specifies the multiarch name for configurations that are +multiarch-enabled but not multilibbed configurations. + +The multiarch name is used to augment the search path for libraries, crt +files and system header files with additional locations. The compiler +will add a multiarch subdirectory of the form +@var{prefix}/@var{multiarch} before each directory in the library and +crt search path. It will also add two directories +@code{LOCAL_INCLUDE_DIR}/@var{multiarch} and +@code{NATIVE_SYSTEM_HEADER_DIR}/@var{multiarch}) to the system header +search path, respectively before @code{LOCAL_INCLUDE_DIR} and +@code{NATIVE_SYSTEM_HEADER_DIR}. + +@code{MULTIARCH_DIRNAME} is not used for configurations that support +both multilib and multiarch. In that case, multiarch names are encoded +in @code{MULTILIB_OSDIRNAMES} instead. + +More documentation about multiarch can be found at +@uref{http://wiki.debian.org/Multiarch}. + @findex SPECS @item SPECS Unfortunately, setting @code{MULTILIB_EXTRA_OPTS} is not enough, since |