Documentation/core-api/symbol-namespaces.rst

15 documentation purposes (think of the SUBSYSTEM_DEBUG namespace) as well as for
18 are required to import the namespace. Otherwise the kernel will, depending on
21 Additionally, it is possible to put symbols into a module namespace, strictly
27 Symbols can be exported into namespace using different methods. All of them are
36 available to export symbols into a certain namespace: EXPORT_SYMBOL_NS() and
37 EXPORT_SYMBOL_NS_GPL(). They take one additional argument: the namespace as a
40 namespace ``USB_STORAGE``, use::
45 ``namespace`` set accordingly. A symbol that is exported without a namespace will
46 refer to ``NULL``. There is no default namespace if none is defined. ``modpost``
47 and kernel/module/main.c make use the namespace at build time or module load
56 and EXPORT_SYMBOL_GPL() macro expansions that do not specify a namespace.
60 is to define the default namespace in the ``Makefile`` of the subsystem. E.g. to
61 export all symbols defined in usb-common into the namespace USB_COMMON, add a
68 still be exported into the namespace that is passed as the namespace argument
69 as this argument has preference over a default symbol namespace.
71 A second option to define the default namespace is directly in the compilation
82 Symbols exported using this macro are put into a module namespace. This
83 namespace cannot be imported.
102 usb_stor_suspend symbol from above, needs to import the namespace USB_STORAGE
107 This will create a ``modinfo`` tag in the module for each imported namespace.
124 referenced from the module for its availability and whether the namespace it
136 modpost will emit a warning if a module uses a symbol from a namespace
147 	- write code that depends on a symbol from a not imported namespace
152 For subsystem maintainers introducing a namespace, the steps are very similar.
153 Again, ``make nsdeps`` will eventually add the missing namespace imports for
156 	- move or add symbols to a namespace (e.g. with EXPORT_SYMBOL_NS())
166 Note: it will happily generate an import statement for the module namespace;