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Mach : A New Kernel Foundation For UNIX Development

Mach : A New Kernel Foundation For UNIX Development. 이 정 호 jeongho.lee at dankook.ac.kr (DSP LAB). Contents. Mach : Introduction Tasks & Threads Virtual Memory IPC System Support Facilities Conclusion. Introduction. Mach

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Mach : A New Kernel Foundation For UNIX Development

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  1. Mach: A New Kernel Foundation For UNIX Development 이 정 호 jeongho.lee at dankook.ac.kr (DSP LAB)

  2. Contents • Mach : Introduction • Tasks & Threads • Virtual Memory • IPC • System Support Facilities • Conclusion

  3. Introduction • Mach • Multiprocessor operating system kernel(Carnegie-Mellon University) • Provided new facilities • Support for multiprocessors • A new virtual memory design(COW,MMF) • A capability-based inter-process communication facility • A number of basic system support facilities Free BSD 1.0 1993 Mach 2.0 1986 Mach 4.0 End:1998 Mach 1985 Mach 3.0 1990 Mach 4.0 1994 Rapsody 1997

  4. Design: an extensible kernel • Extensibility • Object-oriented approach to extensibility • Functions designed to allow complex services and resources • Mach kernel supports four basic abstractions • Task • Thread • Port • Message

  5. Tasks and Threads • UNIX’s process : high overhead on the part of the operating system • Process = task + thread • Task : collection of system resources • Generally high overhead object • Thread : basic unit of computation • Relatively low overhead object • Multiple threads to exist(execute) within a single task • On tightly coupled shared memory multiprocessors • Execution of multiple threads -> can use the full parallelism available • Modest overhead on the part of the kernel.

  6. Virtual Memory Management • The Mach virtual memory design • Allocate regions of virtual memory • Deallocate regions of virtual memory • Set the protections on regions of virtual memory • Specify the inheritance of regions of virtual memory • Copy-on-write and read/write sharing of memory between tasks • Inheritance mechanism • Protection : the current and maximum protection • a combination of read, write, and execute permissions • An important feature Mach’s virtual memory • Handle page-faults and page-out

  7. Virtual Memory Implementation • The basic data structure • address maps • share maps • VM objects • page structures

  8. Virtual Memory Implementation • Machine independent/dependent sections • Machine independent section • Machine dependent section

  9. InterprocessCommunication • Ports and Messages • Port : A finite length queue of messages sent by a task • Message : Fixed length header + variable size collection of typed data object

  10. Interprocess Communication • Ports and Messages • Sending a large message : Copy-On-Write User level User level Kernel level Kernel level

  11. Network communication and security • network servers • Acting as a local representative for tasks on remote nodes • Security guarantees : by network servers through the use of encryption User level Kernel level

  12. System Support Facilities • Kernel Debugger. • Kernel debugger(kdb) based on adb • Enhanced stack traces • Call/return trace support • Instruct counting • Transparent Remote Filesystem • Remote current directories and execution of remote files

  13. Conclusion • The Mach System • Designed as a replacement for the UNIX 4.3 BSD Kernal • Microkernel, move many kernel services to user-level • Task/thread design, virtual memory and IPC • Goal: • ‘kernelize’ : less complex & more easily modifiable basic OS

  14. How did Bonaparte became Emperor of the French? Reference: 9gag.com

  15. References • Mach Project • http://www.cs.cmu.edu/afs/cs.cmu.edu/project/mach/public/www/overview.html • http://www.cimat.mx/~jbhayet/CLASES/VISIONROB/unix.pdf • Mach • http://docs.freebsd.org/cgi/getmsg.cgi?fetch=125750+0+archive/2000/freebsd-chat/20000507.freebsd-chat : • ‘이상한나라의 엘리스’의 Mock Turtle의Mock를 따옴(설) • Mach Overview • https://developer.apple.com/library/mac/#documentation/Darwin/Conceptual/KernelProgramming/Mach/Mach.html • Mach Threads and the Unix Kernel:TheBattle for Control(1987) • Mach’s basic abstractions • http://www.wiley.com/college/silberschatz6e/0471417432/pdf/mach.pdf • The Mach System • http://www.wiley.com/college/silberschatz6e/0471417432/pdf/mach.pdf • 안윤호의 유닉스 역사이야기3 • http://forum.falinux.com/zbxe/?document_srl=536842 • Mach Kernel • http://blog.naver.com/sadman?Redirect=Log&logNo=29544488

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