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-rw-r--r--contrib/libobjc/THREADS43
1 files changed, 23 insertions, 20 deletions
diff --git a/contrib/libobjc/THREADS b/contrib/libobjc/THREADS
index 9dfbbed..8a43683 100644
--- a/contrib/libobjc/THREADS
+++ b/contrib/libobjc/THREADS
@@ -102,30 +102,33 @@ high degree of portability across platforms.
The backend is composed of a file with the necessary code to map the ObjC
thread and mutex to a platform specific implementation. For example, the
-file thr-solaris.c contains the implementation for Solaris. When you
-configure GCC, it attempts to pick an appropriate backend file for the
-target platform; however, you can override this choice by assign the
-OBJC_THREAD_FILE make variable to the basename of the backend file. This
-is especially useful on platforms which have multiple thread libraries.
-For example:
-
- make OBJC_THREAD_FILE=thr-posix
-
-would indicate that the generic posix backend file, thr-posix.c, should be
-compiled with the ObjC runtime library. If your platform does not support
-threads then you should specify the OBJC_THREAD_FILE=thr-single backend file
-to compile the ObjC runtime library without thread or mutex support; note
-that programs which rely upon the ObjC thread and mutex functions will
-compile and link correctly but attempting to create a thread or mutex will
-result in an error.
-
+file thr-solaris.c contains the implementation for Solaris.
+
+If you are compiling libobjc as part of GCC, the thr-objc.c backend is
+always used; this backend uses GCC's gthread code. The thread system
+is automatically configured when GCC is configured. Important: make
+sure you configure GCC using `--enable-threads' if you want threads !
+
+If you want to compile libobjc standalone, then you would need to
+modify the configure.in and makefiles for it; and you need to pick an
+appropriate backend file for the target platform; you make this choice
+by assigning the OBJC_THREAD_FILE make variable to the basename of the
+backend file. For example, OBJC_THREAD_FILE=thr-posix would indicate
+that the generic posix backend file, thr-posix.c, should be compiled
+with the ObjC runtime library. If your platform does not support
+threads then you should specify the OBJC_THREAD_FILE=thr-single
+backend file to compile the ObjC runtime library without thread or
+mutex support; note that programs which rely upon the ObjC thread and
+mutex functions will compile and link correctly but attempting to
+create a thread or mutex will result in an error.
+
It is questionable whether it is really necessary to have both a
frontend and backend function for all available functionality. On the
one hand, it provides a clear, consistent differentiation between what
is public and what is private with the downside of having the overhead
-of multiple functions calls. For example, the function to have a thread
-yield the processor is objc_thread_yield; in the current implementation
-this produces a function call set:
+of multiple functions calls. For example, the function to have a
+thread yield the processor is objc_thread_yield; in the current
+implementation this produces a function call set:
objc_thread_yield() -> __objc_thread_yield() -> system yield function
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