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In posix, test0 makes inter-space ipc for testing extended ipc. This correctly fails when only the cap to ipc to pager is given to all tasks in the container. In order to overcome this problem, the tasks who fork for doing ipc to each other make a request to the pager to get capabilities to do so. Pager finds its own widened ipc capability over the container, replicates it, validates and reduces it to desired boundaries (i.e. just ipc betw. two spaces) and grants it as IMMUTABLE to requesting tasks. This protocol may be useful in implementing a client/server capability request relationship. Code builds but untested.
Codezero POSIX Services This directory contains the source code for the POSIX services developed on top of the Codezero Microkernel. There is a pager called MM0 which demonstrates how a pager on top of Codezero should act, by its system call usage. FS0 is the VFS task that implements File IO via IPC. FS0 can be thought of as a micokernel server. Test0 is the userspace task that tests microkernel system call functionality as well as the POSIX system call functionality by issuing calls to MM0 and FS0. Codezero POSIX services partially demonstrate how a POSIX level operating system would be written on top of Codezero. Unlike shallow implementations on embedded systems that only look like POSIX, mm0 and fs0 implement a real virtual memory subsystem and virtual filesystem that solidly backs the API. Neverhteless services such as terminal IO and common filesystem support are currently missing.