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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/core-api/symbol-namespaces.rst | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/core-api/symbol-namespaces.rst b/Documentation/core-api/symbol-namespaces.rst index 06f766a6aab2..c6f59c5e2564 100644 --- a/Documentation/core-api/symbol-namespaces.rst +++ b/Documentation/core-api/symbol-namespaces.rst @@ -28,6 +28,9 @@ kernel. As of today, modules that make use of symbols exported into namespaces, are required to import the namespace. Otherwise the kernel will, depending on its configuration, reject loading the module or warn about a missing import. +Additionally, it is possible to put symbols into a module namespace, strictly +limiting which modules are allowed to use these symbols. + 2. How to define Symbol Namespaces ================================== @@ -83,6 +86,22 @@ unit as preprocessor statement. The above example would then read:: within the corresponding compilation unit before the #include for <linux/export.h>. Typically it's placed before the first #include statement. +2.3 Using the EXPORT_SYMBOL_GPL_FOR_MODULES() macro +=================================================== + +Symbols exported using this macro are put into a module namespace. This +namespace cannot be imported. + +The macro takes a comma separated list of module names, allowing only those +modules to access this symbol. Simple tail-globs are supported. + +For example: + + EXPORT_SYMBOL_GPL_FOR_MODULES(preempt_notifier_inc, "kvm,kvm-*") + +will limit usage of this symbol to modules whoes name matches the given +patterns. + 3. How to use Symbols exported in Namespaces ============================================ @@ -154,3 +173,6 @@ in-tree modules:: You can also run nsdeps for external module builds. A typical usage is:: $ make -C <path_to_kernel_src> M=$PWD nsdeps + +Note: it will happily generate an import statement for the module namespace; +which will not work and generates build and runtime failures. |