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[patches] Update to option groups documentation
- To: patches@xxxxxxxxxx
- Subject: [patches] Update to option groups documentation
- From: Jim Blandy <jimb@xxxxxxxxxxxxxxxx>
- Date: Fri, 13 Apr 2007 17:52:30 -0700
I've committed the following change to EGLIBC.option-groups, bringing
it up to date with the way things actually are at this point.
2007-04-13 Jim Blandy <jimb@xxxxxxxxxxxxxxxx>
* EGLIBC.option-groups: Doc fixes.
--- EGLIBC.option-groups (revision 1969)
+++ EGLIBC.option-groups (revision 1970)
@@ -56,11 +56,39 @@
The Option Groups
+EGLIBC currently implements the following option groups, also
+documented in the file 'option-groups.def':
+ This option group includes functions for accessing message
+ catalogs: catopen, catclose, and catgets.
+ This option group includes all locale definitions other than
+ those for the "C" locale. If this option group is omitted, then
+ only the "C" locale is supported.
+ This option group includes the 'libm' library, containing
+ mathematical functions. If this option group is omitted, then
+ an EGLIBC installation does not include shared or unshared versions
+ of the math library.
+ Note that this does not remove all floating-point related
+ functionality from EGLIBC; for example, 'printf' and 'scanf'
+ can still print and read floating-point values with this option
+ group disabled.
+ Note that the ISO Standard C++ library 'libstdc++' depends on
+ EGLIBC's math library 'libm'. If you disable this option
+ group, you will not be able to build 'libstdc++' against the
+ resulting EGLIBC installation.
The POSIX.1-2001 specification includes a suggested partition of all
the functions in the POSIX C API into option groups: math functions
like 'sin' and 'cos'; networking functions like 'socket' and
-'connect'; and so on. EGLIBC uses this partitioning as the basis for
-its own option groups, and follows the POSIX naming scheme.
+'connect'; and so on. EGLIBC could use this partitioning as the basis
+for future option groups.
@@ -76,31 +104,25 @@
default values for all variables; all option groups are enabled by
-For example, the following 'option-groups.config' would omit
-mathematical functions, but include networking functions, and
+For example, the following 'option-groups.config' would omit locale
+data, but include mathematical functions, and everything else:
- OPTION_POSIX_C_LANG_MATH = n
- OPTION_POSIX_NETWORKING = y
+ OPTION_EGLIBC_LOCALES = n
+ OPTION_EGLIBC_LIBM = y
In general, each option group variable controls whether a given set of
object files in EGLIBC is compiled and included in the final
libraries, or omitted from the build.
-Each subdirectory's Makefile categorizes its routines by option group.
-For example, EGLIBC's 'inet/Makefile' places its functions in the
-POSIX_NETWORKING group as follows:
+Each subdirectory's Makefile categorizes its routines, libraries, and
+executables by option group. For example, EGLIBC's 'math/Makefile'
+places the 'libm' library in the OPTION_EGLIBC_LIBM group as follows:
- routines-$(OPTION_POSIX_NETWORKING) += \
- htonl htons \
- inet_lnaof inet_mkadr \
- inet_netof inet_ntoa inet_net herrno herrno-loc \
- gethstbyad gethstbyad_r gethstbynm gethstbynm2 gethstbynm2_r \
+ extra-libs-$(OPTION_EGLIBC_LIBM) := libm
Finally, common code in 'Makerules' cites the value of the variable
-'routines-y', selecting only those object files that belong to enabled
-option groups for inclusion in the resulting libraries.
+'extra-libs-y', selecting only those libraries that belong to enabled
+option groups to be built.
Current Status and Future Directions