Dissertations / Theses on the topic 'DOS device drivers (Computer programs)'

Thesis (MSc)--Stellenbosch University, 2000.
ENGLISH ABSTRACT: Users are not supposed to modify an operating system kernel, but it is often necessary to add a device driver for a new peripheral device. Device driver development is a difficult and time-consuming process that must be performed by an expert. Drivers are difficult to debug and a malfunctioning driver could cause the operating system to crash. Ways are therefore needed to make the development of device drivers safer and easier. A number of different device driver development methods are examined in this thesis. An existing micro-kernel that supports in-kernel device drivers as well as extensible device drivers has been modified to support user-level and loadable drivers. These extensions ensured that all the development methods were implemented in the same environment and a comparison could thus be made on a fair basis. A comparison of the different methods with respect to the efficiency of the resulting device driver, as well as the ease of the development process, is presented.
AFRIKAANSE OPSOMMING: Gebruikers is nie veronderstelom aan 'n bedryfstelsel te verander nie, maar tog is dit gereeld nodig om 'n toesteldrywer vir 'n nuwe randapparaat by te voeg. Die ontwikkeling van 'n toesteldrywer is 'n tydrowende en moeilike proses en moet deur 'n kundige aangepak word. Toesteldrywers is moeilik om te ontfout en kan deur verkeerde werking die hele stelsel tot stilstand bring. Daar is dus tegnieke nodig om die ontwikkeling van toestelhanteerders makliker en veiliger te maak. 'n Aantal verskillende ontwikkelingsmetodes vir toesteldrywers word in hierdie tesis ondersoek. 'n Bestaande mikro-kern wat in-kern, sowel as uitbreibare toesteldrywers ondersteun, is aangepas om gebruikersvlak en laaibare toestelhanteerders te ondersteun. Hierdie uitbreiding het verseker dat al die ontwikkelingsmetodes in dieselfde omgewing geïmplementeer is. Dit was dus moontlik om die metodes op 'n regverdige grondslag te vergelyk. Die vergelyking is gedoen ten opsigte van die effektiwiteit van die resulterende toesteldrywer sowel as die moeilikheidsgraad van die ontwikkelingsproses.

New peripheral devices are being developed at an ever increasing rate. Before such accessories can be used in the UNIX environment (UNIX is a trademark of Bell Laboratories), they must be able to communicate with the operating system. This involves writing a device driver for each device. In order to do this, very detailed knowledge is required of both the device to be integrated and the version of UNIX to which it will be attached. The process is long, detailed and prone to subtle problems and errors. This paper presents a menu-driven utility designed to simplify and accelerate the design and implementation of UNIX device drivers by freeing developers from many of the implementation specific low-level details.

New hardware devices are continually being released to the public by hardware manufactures around the world. For these new devices to be usable under a PC operating system, device drivers that extend the functionality of the target operating system have to be constructed. This work examines and compares the device driver architectures currently in use by two of the most widely used operating systems, Microsoft’s Windows and Linux. The IEEE1394 (high speed serial bus) device driver stacks on each operating system are examined and compared as an example of a major device driver stack implementation, including driver requirements for the upcoming IEEE1394.1 bridging standard.

Thesis (M.S. in Systems Engineering)--Naval Postgraduate School, December 2004.
Thesis advisor(s): Singh Gurminder, John Gibson. Includes bibliographical references (p. 65-66). Also available online.

Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2003.
Includes bibliographical references (leaves 20-21).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Linux has become a viable alternative to Windows in recent years. This investigation looks at the feasibility of porting the software for a PC-based medical device to Linux. Using an open-source operating system frees developers from the constraints imposed by relying on a single company for the development platform. Several porting methods are considered. The port method chosen allows development on the Windows version to continue while simultaneously testing on Linux, without creating separate versions of the software. Differences in the way the software interacts with the operating system and with the hardware have to be addressed. A Linux environment was created in which to run the software and determine how to reconcile these differences. No major hurdles to using Linux exist, so it appears to be a viable platform on which to conduct future development.
by Steven B. Lustbader.
M.Eng.and S.B.

The World Wide Web is becoming a basic infrastructure for a variety of services, and the increases in audience size and client network bandwidth create service demands that are outpacing server capacity. Web clusters are one solution to this need for highperformance, highly available web server systems. We are interested in load distribution techniques, specifically Layer-7 algorithms that are content-aware. Layer- 7 algorithms allow distribution control based on the specific content requested, which is advantageous for a system that offers highly heterogenous services. We examine the performance of the Client Aware Policy (CAP) on a Linux/Apache web cluster consisting of a single web switch that directs requests to a pool of dual-processor SMP nodes. We show that the performance advantage of CAP over simple algorithms such as random and round-robin is as high as 29% on our testbed consisting of a mixture of static and dynamic content. Under heavily loaded conditions however, the performance decreases to the level of random distribution. In studying SMP vs. uniprocessor performance using the same number of processors with CAP distribution, we find that SMP dual-processor nodes under moderate workload levels provide equivalent throughput as the same number of CPU’s in a uniprocessor cluster. As workload increases to a heavily loaded state however, the SMP cluster shows reduced throughput compared to a cluster using uniprocessor nodes. We show that the web cluster’s maximum throughput increases linearly with the addition of more nodes to the server pool. We conclude that CAP is advantageous over random or round-robin distribution under certain conditions for highly dynamic workloads, and suggest some future enhancements that may improve its performance.

Thesis (MScEng)--University of Stellenbosch, 2003.
ENGLISH ABSTRACT: The Linux operating system and shared Ethernet are alternative technologies with the potential to reduce both the development time and costs of satellites as well as the supporting infrastructure. Modular satellites, ground stations and rapid proto typing testbeds also have a common requirement for distributed real-time computation. The identified technologies were investigated to determine whether this requirement could also be met. Various real-time extensions and modifications are currently available for the Linux operating system. A suitable open source real-time extension called Real-Time Application Interface (RTAI) was selected for the implementation of an experimental distributed real-time system. Experimental results showed that the RTAI operating system could deliver deterministic realtime performance, but only in the absence of non-real-time load. Shared Ethernet is currently the most popular and widely used commercial networking technology. However, Ethernet wasn't developed to provide real-time performance. Several methods have been proposed in literature to modify Ethernet for real-time communications. A token passing protocol was found to be an effective and least intrusive solution. The Real-Time Token (RTToken) protocol was designed to guarantee predictable network access to communicating real-time tasks. The protocol passes a token between nodes in a predetermined order and nodes are assigned fixed token holding times. Experimental results proved that the protocol offered predictable network access with bounded jitter. An experimental distributed real-time system was implemented, which included the extension of the RTAI operating system with the RTToken protocol, as a loadable kernel module. Real-time tasks communicated using connectionless Internet protocols. The Real-Time networking (RTnet) subsystem of RTAI supported these protocols. Under collision-free conditions consistent transmission delays with bounded jitter was measured. The integrated RTToken protocol provided guaranteed and bounded network access to communicating real-time tasks, with limit overheads. Tests exhibited errors in some of the RTAI functionality. Overall the investigated technologies showed promise in being able to meet the distributed real-time requirements of various applications, including those found in the satellite environment.
AFRIKAANSE OPSOMMING: Die Linux bedryfstelsel en gedeelde Ethernet is geïdentifiseer as potensiële tegnologieë vir satelliet bedryf wat besparings in koste en vinniger ontwikkeling te weeg kan bring. Modulêr ontwerpte satelliete, grondstasies en ontwikkeling platforms het 'n gemeenskaplike behoefte vir verspreide intydse verwerking. Verskillende tegnologieë is ondersoek om te bepaal of aan die vereiste ook voldoen kan word. Verskeie intydse uitbreidings en modifikasies is huidiglik beskikbaar vir die Linux bedryfstelsel. Die "Real-Time Application Interface" (RTAI) bedryfstelsel is geïdentifiseer as 'n geskikte intydse uitbreiding vir die implementering van 'n eksperimentele verspreide intydse stelsel. Eksperimentele resultate het getoon dat die RTAI bedryfstelsel deterministies en intyds kan opereer, maar dan moet dit geskied in die afwesigheid van 'n nie-intydse verwerkingslas. Gedeelde Ethernet is 'n kommersiële network tegnologie wat tans algemeen beskikbaar is. Die tegnologie is egter nie ontwerp vir intydse uitvoering nie. Verskeie metodes is in die literatuur voorgestelom Ethernet te modifiseer vir intydse kommunikasie. Hierdie ondersoek het getoon dat 'n teken-aangee protokol die mees effektiewe oplossing is en waarvan die implementering min inbreuk maak. Die "Real-Time Token" (RTToken) protokol is ontwerp om voorspelbare netwerk toegang tot kommunikerende intydse take te verseker. Die protokol stuur 'n teken tussen nodusse in 'n voorafbepaalde volgorde. Nodusse word ook vaste teken hou-tye geallokeer. Eksperimentele resultate het aangedui dat die protokol deterministiese netwerk toegang kan verseker met begrensde variasies. 'n Eksperimentele verspreide intydse stelsel is geïmplementeer. Dit het ingesluit die uitbreiding van die RTAI bedryfstelsel met die RTToken protokol; verpak as 'n laaibare bedryfstelsel module. Intydse take kan kommunikeer met verbindinglose protokolle wat deur die "Real-Time networking" (RTnet) substelsel van RTAI ondersteun word. Onder ideale toestande is konstante transmissie vertragings met begrensde variasies gemeet. Die integrasie van die RTToken protokol het botsinglose netwerk toegang aan kommunikerende take verseker, met beperkte oorhoofse koste as teenprestasie. Eksperimente het enkele foute in die funksionaliteit van RTAI uitgewys. In die algemeen het die voorgestelde tegnologieë getoon dat dit potensiaal het vir verskeie verspreide intydse toepassings in toekomstige satelliet en ook ander omgewings.

The purpose of this study is to explore the relationship between hit ratio of cache memory and design parameters. Cache memories are widely used in the design of computer system architectures to match relatively slow memories against fast CPUs. Caches hold the active segments of a program which are currently in use. Since instructions and data in cache memories can be referenced much faster than the time required to access main memory, cache memories permit the execution rate of the machine to be substantially increased. In order to function effectively, cache memories must be carefully designed and implemented. In this study, a trace-driven simulation study of direct mapped, associative mapped and set-associative mapped cache memories is made. In the simulation, cache fetch algorithm, placement policy, cache size and various parameters related to cache design and the resulting effect on system performance is investigated. The cache memories are simulated using the C language and the simulation results are analyzed for the design and implementation of cache memories.
Department of Physics and Astronomy

X windows is a graphic display management system. It is designed to work on a variety of machines and display adapters, however it is not designed for terminals with local graphics capabilities. X windows can be made to work on this type of terminal, although in a slower and restricted form. The problem with designing a variation of X for these terminals is the translation from X requests to native graphics commands, and the mapping of terminal input into X events. These implementation issues are discussed and example code is provided.
Department of Computer Science

Device drivers are Operating Systems (OS) extensions that enable the use of I/O devices in computing systems. However, studies have identified drivers as an Achilles’ heel of system reliability, their high fault rate accounting for a significant portion of system failures. Consequently, significant effort has been directed towards improving system robustness by protecting system components (e.g., OS kernel, I/O devices, etc.) from the harmful effects of driver faults. In contrast to prior techniques which focused on preventing unsafe driver interactions (e.g., with the OS kernel), my thesis is that checking a driver’s execution for correctness violations results in the detection and mitigation of more faults. To validate this thesis, I present Guardrail, a flexible and powerful framework that enables instruction-grained dynamic analysis (e.g., data race detection) of unmodified kernel-mode driver binaries to safeguard I/O operations and devices from driver faults. Guardrail decouples the analysis tool from driver execution to improve performance, and runs it in user-space to simplify the deployment of new tools. Moreover, Guardrail leverages virtualization to be transparent to both the driver and device, and enable support for arbitrary driver/device combinations. To demonstrate Guardrail’s generality, I implemented three novel dynamic checking tools within the framework for detecting memory faults, data races and DMA faults in drivers. These tools found 25 serious bugs, including previously unknown bugs, in Linux storage and network drivers. Some of the bugs existed in several Linux (and driver) releases, suggesting their elusiveness to existing approaches. Guardrail easily detected these bugs using common driver workloads. Finally, I present an evaluation of using Guardrail to protect network and storage I/O operations from memory faults, data races and DMA faults in drivers. The results show that with hardware-assisted logging for decoupling the heavyweight analyses from driver execution, standard I/O workloads generally experienced negligible slowdown on their end-to-end performance. In conclusion, Guardrail’s high fidelity fault detection and efficient monitoring performance makes it a promising approach for improving the resilience of computing systems to the wide variety of driver faults.

Since the need of energy conservation has become more and more urgent in the past decades, there has been an increased interest in the study and development of more efficient energy conversion systems. One of the fields that have arisen from that endeavor is a branch of physics called Finite Time Thermodynamics (FIT). It may be said that FIT was initiated through the famous paper by Curzon and Ahlborn (1975) that established new bounds on the efficiency of a finite time Carnot heat engine. Before, the traditional treatments gave a fundamental upper limit on the efficiency of any heat engine. However, this figure, the well-known Carnot efficiency, is far too optimistic in comparison to real heat engines. The reason lies in the fact that the traditional Carnot engine is operating infinitely slowly, thus having zero power output. Curzon and Ahlborn were able to improve upon this treatment and to set an upper limit on engines producing finite power.

Alors que la recherche sur la qualité du code des systèmes a connu un formidable engouement, les systèmes d'exploitation sont encore aux prises avec des problèmes de fiabilité notamment dus aux bogues de programmation au niveau des services noyaux tels que les pilotes de périphériques et l'implémentation des systèmes de fichiers. Des études ont en effet montré que chaque version du noyau Linux contient entre 600 et 700 fautes, et que la propension des pilotes de périphériques à contenir des erreurs est jusqu'à sept fois plus élevée que toute autre partie du noyau. Ces chiffres suggèrent que le code des services noyau n'est pas suffisamment testé et que de nombreux défauts passent inaperçus ou sont difficiles à réparer par des programmeurs non-experts, ces derniers formant pourtant la majorité des développeurs de services. Cette thèse propose une nouvelle approche pour le débogage et le test des services noyau. Notre approche est focalisée sur l'interaction entre les services noyau et le noyau central en abordant la question des "trous de sûreté" dans le code de définition des fonctions de l'API du noyau. Dans le contexte du noyau Linux, nous avons mis en place une approche automatique, dénommée Diagnosys, qui repose sur l'analyse statique du code du noyau afin d'identifier, classer et exposer les différents trous de sûreté de l'API qui pourraient donner lieu à des fautes d'exécution lorsque les fonctions sont utilisées dans du code de service écrit par des développeurs ayant une connaissance limitée des subtilités du noyau. Pour illustrer notre approche, nous avons implémenté Diagnosys pour la version 2.6.32 du noyau Linux. Nous avons montré ses avantages à soutenir les développeurs dans leurs activités de tests et de débogage.

Existuje veľa rôznych dôvodov pre spoločnosti a organizácie, prečo by mali investovať do virtualizácie. Asi najväčší dôvod je finančná motivácia, pretože nasadenie virtualizácie môže ušetriť nemálo peňazí. Táto práca sa zaoberá práve problémom virtualizácie I/O operácií v sieťovom prostredí. Cieľom práce je tvorba softvérových ovládačov pre I/O virtualizáciu, ktoré by mohli pracovať s hardvérovo akcelerovanými sieťovými kartami. Hlavným prínosom ovládačov by mala byť použiteľnosť a čo najmenšia strata prenosového výkonu vo virtualizovanom prostredí. Pred popisom finálnych detailov ovládačov je však potrebné uviesť potrebné teoretické základy. Teoretická časť sa zaoberá súčasnými trendami vo virtualizácii I/O, technológiami ako sú virtio, vhost, SR-IOV, VFIO a mdev. V praktickej časti sú navrhuté dva spôsoby riešenia problému. Prvým je použitie technológie virtio (emulácia softvéru). Druhé je založené na technológii VFIO-mdev (hybridná paravirtualizácia). Pokiaľ sa jedná o výkon a konfigurovateľnosť zariadení, oba prístupy majú rôzne benefity. Tieto riešenia majú aj svoje nevýhody, ako je zložitosť riešenia a náročnosť integrácie do systému. Požadované ciele boli úspešne dosiahnuté vo forme prototypu ovládača nfb_mdev.

abstract: This research describes software based remote attestation schemes for obtaining the integrity of an executing user application and the Operating System (OS) text section of an untrusted client platform. A trusted external entity issues a challenge to the client platform. The challenge is executable code which the client must execute, and the code generates results which are sent to the external entity. These results provide the external entity an assurance as to whether the client application and the OS are in pristine condition. This work also presents a technique where it can be verified that the application which was attested, did not get replaced by a different application after completion of the attestation. The implementation of these three techniques was achieved entirely in software and is backward compatible with legacy machines on the Intel x86 architecture. This research also presents two approaches to incorporating software based "root of trust" using Virtual Machine Monitors (VMMs). The first approach determines the integrity of an executing Guest OS from the Host OS using Linux Kernel-based Virtual Machine (KVM) and qemu emulation software. The second approach implements a small VMM called MIvmm that can be utilized as a trusted codebase to build security applications such as those implemented in this research. MIvmm was conceptualized and implemented without using any existing codebase; its minimal size allows it to be trustworthy. Both the VMM approaches leverage processor support for virtualization in the Intel x86 architecture.
Dissertation/Thesis
Ph.D. Computer Science 2011

This thesis discusses the motivation, origin, history, design guidelines, API, the device drivers and userland utilities of the hardware sensors framework available in OpenBSD. The framework spans multiple utilities in the base system and the ports tree, is utilised by over 75 drivers, and is considered to be a distinctive and ready-to-use feature that sets OpenBSD apart from many other operating systems, and in its root is inseparable from the OpenBSD experience. The present framework, however, is missing the functionality that would allow the user to interface with the fan-controlling part of the hardware monitors. We therefore discuss the topic of fan control and introduce sysctl-based interfacing with the fan-controlling capabilities of microprocessor system hardware monitors. The discussed prototype implementation reduces the noise and power-consumption characteristics in fans of personal computers, especially of those PCs that are designed from off-the-shelf components. We further argue that our prototype is easier, more intuitive and robust compared to solutions available elsewhere.