Hey, I am currently looking for a way to reclaim resources allocated by kernel for the rootserver thread, i.e. memory for CNode, TCB, BootInfo, etc. My current approach looks like this:
* in rootserver instead of calling seL4_TCB_Suspend, call custom syscall seL4_ReclaimRootserverResources. This sycall as parameters takes CNode and slot no. after which kernel should be able to freely write new caps. This CNode is main CNode of some component initialized by the rootserver. * implmenetation of this syscall then suspends initial thread, schedules new thread, revokes most of rootserver's resources, notably TCB, BootInfo, IPCBuffer, VSpace and CNode. Then for those now free memory regions new untyped capabilities are created, with the same sizes as the original objects. Lastly, new capabilities are written to subsequent slots in CNode a'la boot.c, so with null MDBNode; mdbRevocable and mdbFirstBadged set to true. This solution has couple of problems. First and foremost, it requires creating additional syscall to handle this. Secondly, even though the component _technically_ has access to this newly created capabilities, it doesn't know where they are, or how big they are. This could be partially band-aided by hardcoding this information in relevant component, but that is far from elegant. This component also recives rest of the untyped memory from rootserver, including bootinfo entries about this memory specification, so that renders solution with hardcoding spec even worse. Last but not least, before the seL4_ReclaimRootserverResources is called, all the components are resumed using seL4_TCB_Resume as part of rootserver's work, so there could be race-condition between calling reclaiming syscall, and component initialization (although I am not 100% sure about that part) Is there maybe a better way to do it, and I am doing it all round? The perfect solution would be to somehow extend bootinfo and/or remaining untypeds that were given by the kernel to the rootserver. _______________________________________________ Devel mailing list -- devel@sel4.systems To unsubscribe send an email to devel-leave@sel4.systems
