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This commit introduces a Cap_index class for Fiasco.OC's capabilities. A Cap_index is a combination of the global capability id, that is used by Genode to correctly identify a kernel-object, and a corresponding entry in a protection-domain's (kernel-)capability-space. The cap-indices are non-copyable, unique objects, that are held in a Cap_map. The Cap_map is used to re-find capabilities already present in the protection-domain, when a capability is received via IPC. The retrieval of capabilities effectively fixes issue #112, meaning the waste of capability-space entries. Because Cap_index objects are non-copyable (their address indicates the position in the capability-space of the pd), they are inappropriate to use as Native_capability. Therefore, Native_capability is implemented as a reference to Cap_index objects. This design seems to be a good pre-condition to implement smart-pointers for entries in the capability-space, and thereby closing existing leaks (please refer to issue #32). Cap_index, Cap_map, and the allocator for Cap_index objects are designed in a way, that it should be relatively easy to apply the same concept to NOVA also. By now, these classes are located in the `base-foc` repository, but they intentionally contain no Fiasco.OC specific elements. The previously explained changes had extensive impact on the whole Fiasco.OC platform implementation, due to various dependencies. The following things had to be changed: * The Thread object's startup and destruction routine is re-arranged, to enable another thread (that calls the Thread destructor) gaining the capability id of the thread's gate to remove it from the Cap_map, the thread's UTCB had to be made available to the caller, because there is the current location of that id. After having the UTCB available in the Thread object for that reason, the whole thread bootstrapping could be simplified. * In the course of changing the Native_capability's semantic, a new Cap_mapping class was introduced in core, that facilitates the establishment and destruction of capability mappings between core and it's client's, especially mappings related to Platform_thread and Platform_task, that are relevant to task and thread creation and destruction. Thereby, the destruction of threads had to be reworked, which effectively removed a bug (issue #149) where some threads weren't destroyed properly. * In the quick fix for issue #112, something similar to the Cap_map was introduced available in all processes. Moreover, some kind of a capability map already existed in core, to handle cap-session request properly. The introduction of the Cap_map unified both structures, so that the cap-session component code in core had to be reworked too. * The platform initialization code had to be changed sligthly due to the changes in Native_capability * The vcpu initialization in the L4Linux support library had to be adapted according to the already mentioned changes in the Thread object's bootstrap code. |
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