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d306d6b451
Modifying task_virt_to_page() so that it takes into account page protections. If mm0 writes to a task page that is meant to be read-only, (e.g. the zero page) the design is broken. Every access to a task's page will take the page fault route, and the page fault handler will return the page instead of 0.
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.