Integration of Generic Operating Systems in Partitioned Architectures (presentation)

Provas públicas do Mestrado em Engenharia Informática 22 September 2009, Lisbon, Portugal Integration of Generic Operating Systems in Partitioned Architectures João Pedro Gonçalves Crespo Craveiro Supervisor: Prof. José Rufino Copyright © 2008-2009 Navigators - LASIGE – FCUL

Outline • Aerospace applications: concepts • AIR: ARINC 653 In Space RTOS • Improving the AIR Technology – AIR POS Adaptation Layer – Enhanced timeliness mechanisms • Integration of generic operating systems – Case study: (Embedded) Linux • Concluding remarks and future work 1-2 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 2

• Aerospace applications: concepts • AIR: ARINC 653 In Space RTOS • Improving the AIR Technology – AIR POS Adaptation Layer – Enhanced timeliness mechanisms • Integration of generic operating systems – Case study: (Embedded) Linux • Concluding remarks and future work 1-3 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 3

ARINC 653 specification • Important part of IMA – Partition environment – Multiple functions, of different criticality levels – Shared computing platform • Standard interface between application software and operating system Partition management, process management, time management, inter- and intrapartition communication, health monitoring Optional services (ARINC 653 Part 2) 1-4 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 4

Temporal and spatial segregation • Temporal segregation – Activities in one partition do not interfere with the remaining partitions – Fixed cyclic scheduling of partitions • Spatial segregation – Applications in one partition cannot access memory zones outside that partition 1-5 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 5

IMA/ARINC 653 in space • Space industry players, ESA: – Identified similarities between the requirements of space and aeronautical apps – Established requirements for the employment of the IMA concepts in space – No major technological feasibility impairments identified • Following the interest of ESA: – Proof of concept – Demonstration of feasibility AIR ARINC 653 In Space RTOS 1-7 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 7

AIR system architecture • Time and space partitioning • Two-level hierarchical scheduling • Hardware and OS independence • Different OSs among partitions 1-8 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 8

AIR system architecture AIR PMK • Fixed cyclic partition scheduling (first level) – Second level (process): native partition OS process scheduler • Partition dispatching – Notify heir partition of clock ticks elapsed while it was inactive – Partition context save and restore • Mode-based schedules (NEW) 1-9 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 9

AIR system architecture APEX and AIR HM • Flexible Portable APEX – Services defined in ARINC 653 – Generic OSs: only subset of the APEX services • Management/monitoring, interpartition communication • AIR Health Monitoring (HM) – Responsible for handling HW/SW errors – Isolate errors within domain of occurence • Process • Partition • System 1-10 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 10

Time and space partitioning Time partitioning Space partitioning • Two-level hierarchical • High-level processor- scheduling independent abstraction • Fixed cyclic partition • Mapping of high-level scheduling, RTOS partition description to process scheduling low-level mechanisms 1-11 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 11

AIR POS Adaptation Layer • Evolved from a paravirtualization layer below the POS • Identified requirement for integration of generic OSs • Confirmed observation that partitions hosting RTOSs would also benefit from its presence 1-13 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 13

AIR POS Adaptation Layer Flexible POS integration • POS-independent PMK 1. POS initialization procedures 2. Interface with AIR PMK components (e.g. partition scheduler/dispatcher) • APEX 3. Map sys calls onto POS or AIR-specific services • HM 4. Triggered by raising exception 1-14 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 14

AIR POS Adaptation Layer Development process • Separation of concerns • Reusable building blocks • Less time spent on interactions • Modifications restricted, better validation efforts 1-15 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 15

Enhanced timeliness mechanisms Mode-based schedules • Adaptation to different modes/phases of operation • Accomomodation of component failure • Schedule change only becomes effective at the end of the MTF 1-16 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 16

Enhanced timeliness mechanisms Process deadline monitoring • Process may miss deadline when partition inactive – Operational fault – Uncertain WCET, partition windows underdimensioned • Only earliest deadlines verified, right after clock tick update 1-17 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 17

Integration of generic operating systems • Motivation: – Application portability • Interpreted / scripting languages – Hardware interface / device driver availability • Case study – (Embedded) Linux: – Open source – Portable (processor architectures, HW configurations) – Modular and configurable – Soft real-time developments 1-20 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 20

Embedded Linux • Approach: – Configuration of a vanilla Linux kernel • Portability/maintainability – Smaller system library (uClibc)‫‏‬ • Optimized /trimmed implementations – Provision of standard commands more efficiently (BusyBox)‫‏‬ • Optimized/trimmed implementations • Single executable file 1-21 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 21

Embedded Linux Overall results • Linux kernel 2.6 • uClibc • Busybox (system tools) Entire Linux OS fitting in less than 2 MiB Will coexist with other POSs and reside always in memory 1-22 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 22

Integration of Linux in AIR Paravirtualization in Linux • Temporal partitioning ensurance inherent – But Linux can still undermine it • Paravirtualization – Not all ISAs fully virtualizable • VMI / paravirt-ops – Allows same kernel to run either natively or as paravirtualized guest 1-23 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 23

Integration of Linux in AIR Linux partition and AIR PAL • In AIR, AIR PAL will provide the VMI layer to the POS • Interactions with the AIR PMK when required 1-24 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 24

Concluding remarks (I) • New component, AIR PAL, allowing: – stable POS-independent AIR PMK – homogenous POS integration; – better development process workflow • Advanced timeliness adaptation and monitoring mechanisms – absent in other ARINC 653/TSP solutions, both opensource‫(‏‬XtratuM)‫‏‬and‫‏‬commercial‫(‏‬Wind‫‏‬River’s‫‏‬ VxWorks 653) 1-26 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 26

Concluding remarks (II) • Study of Linux as a generic non-RT POS in AIR – Embedded approach yields encouraging results, given the POS coexistence in memory – Proposal of paravirtualization mechanisms to guarantee Linux does not compromise TSP-related safety – Implementation of AIR prototype complete with a Linux partition was deemed incompatible with the duration of the project 1-27 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 27

Future work • Direct follow-ups – Prototype implementation (IA-32, SPARC) – Extend to other generic POSs, like Windows (WRK) • Consolidate/extend TSP support – Integrate interactions with environment, via sensors/actuators • TSP scheduling and multicore – Working plan approved for funding through an Individual Doctoral Grant from FCT 1-28 João Craveiro, LaSIGE/FCUL, Portugal <jcraveiro@lasige.di.fc.ul.pt> Provas públicas do Mestrado em Engenharia Informática Copyright © 2008-2009 Navigators - LASIGE – FCUL 28

Questions? More information: • AIR projects website, at http://air.di.fc.ul.pt • J. Craveiro, J. Rufino, C. Almeida, R. Covelo, and P.‫‏‬Venda,‫“‏‬Embedded Linux in a partitioned architecture for aerospace applications,”‫‏‬in‫‏‬Proc. 7th ACS/IEEE Int’l Conf. on Computer Systems and Applications, Rabat, Morocco, May 2009. • J. Rufino, J. Craveiro, T. Schoofs, C. Tatibana,‫‏‬and‫‏‬J.‫‏‬Windsor,‫“‏‬AIR Technology: a step towards ARINC 653 in space,”‫‏‬in‫‏‬DASIA 2009 "DAta Systems In Aerospace" Conference, Istanbul, Turkey, May 2009. • J. Craveiro, J. Rufino, T. Schoofs,‫‏‬and‫‏‬J.‫‏‬Windsor,‫“‏‬Flexible Operating System Integration in Partitioned Aerospace Systems,”‫‏‬in‫‏‬INForum 2009 – Simpósio de Informática, Lisbon, Portugal, Sep. 2009. (Nominated for Best Student Paper award) João Craveiro LaSIGE/FCUL, Lisboa, Portugal Homepage: http://lasige.di.fc.ul.pt/~jcraveiro/ E-mail: jcraveiro@lasige.di.fc.ul.pt Copyright © 2008-2009 Navigators - LASIGE – FCUL