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Diffstat (limited to 'Documentation/core-api/symbol-namespaces.rst')
| -rw-r--r-- | Documentation/core-api/symbol-namespaces.rst | 19 |
1 files changed, 9 insertions, 10 deletions
diff --git a/Documentation/core-api/symbol-namespaces.rst b/Documentation/core-api/symbol-namespaces.rst index 12e4aecdae94..06f766a6aab2 100644 --- a/Documentation/core-api/symbol-namespaces.rst +++ b/Documentation/core-api/symbol-namespaces.rst @@ -41,12 +41,12 @@ entries. In addition to the macros EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL(), that allow exporting of kernel symbols to the kernel symbol table, variants of these are available to export symbols into a certain namespace: EXPORT_SYMBOL_NS() and -EXPORT_SYMBOL_NS_GPL(). They take one additional argument: the namespace. -Please note that due to macro expansion that argument needs to be a -preprocessor symbol. E.g. to export the symbol ``usb_stor_suspend`` into the +EXPORT_SYMBOL_NS_GPL(). They take one additional argument: the namespace as a +string constant. Note that this string must not contain whitespaces. +E.g. to export the symbol ``usb_stor_suspend`` into the namespace ``USB_STORAGE``, use:: - EXPORT_SYMBOL_NS(usb_stor_suspend, USB_STORAGE); + EXPORT_SYMBOL_NS(usb_stor_suspend, "USB_STORAGE"); The corresponding ksymtab entry struct ``kernel_symbol`` will have the member ``namespace`` set accordingly. A symbol that is exported without a namespace will @@ -68,7 +68,7 @@ is to define the default namespace in the ``Makefile`` of the subsystem. E.g. to export all symbols defined in usb-common into the namespace USB_COMMON, add a line like this to drivers/usb/common/Makefile:: - ccflags-y += -DDEFAULT_SYMBOL_NAMESPACE=USB_COMMON + ccflags-y += -DDEFAULT_SYMBOL_NAMESPACE='"USB_COMMON"' That will affect all EXPORT_SYMBOL() and EXPORT_SYMBOL_GPL() statements. A symbol exported with EXPORT_SYMBOL_NS() while this definition is present, will @@ -78,11 +78,10 @@ as this argument has preference over a default symbol namespace. A second option to define the default namespace is directly in the compilation unit as preprocessor statement. The above example would then read:: - #undef DEFAULT_SYMBOL_NAMESPACE - #define DEFAULT_SYMBOL_NAMESPACE USB_COMMON + #define DEFAULT_SYMBOL_NAMESPACE "USB_COMMON" -within the corresponding compilation unit before any EXPORT_SYMBOL macro is -used. +within the corresponding compilation unit before the #include for +<linux/export.h>. Typically it's placed before the first #include statement. 3. How to use Symbols exported in Namespaces ============================================ @@ -94,7 +93,7 @@ for the namespaces it uses symbols from. E.g. a module using the usb_stor_suspend symbol from above, needs to import the namespace USB_STORAGE using a statement like:: - MODULE_IMPORT_NS(USB_STORAGE); + MODULE_IMPORT_NS("USB_STORAGE"); This will create a ``modinfo`` tag in the module for each imported namespace. This has the side effect, that the imported namespaces of a module can be |