Chapter 7
Testing, Checking, and Hardware
Syndrome
Abstract In previous chapters, we introduced the processes of checking and
testing, the first of the three main processes of Generalized Algorithm of Fault
Tolerance—GAFT. In this chapter, we further discuss the process of checking
hardware, at first software-based hardware-checking and at second hardware-based
checking. For the software-based hardware checking, we show what a
software-based test should include, when they are the preferred choice over
hardware-based checking schemes, and especially how such tests can be scheduled
in the system without interfering with ongoing real-time tasks. Further to support
handling of hardware-based checking, we introduce a new system condition
descriptor—so-called a syndrome, and illustrate how it can be used as a mechanism
to signal to the operating system the hardware condition, including manifestation of
detected error. We then show the steps the runtime system performs to eliminate the
fault and in case of permanent errors how the software can reconfigure the hardware
to exclude the faulty element. We also explain in which cases software has to adapt
to the new hardware topology. We start by explaining how software-based checks
can be used to detect hardware faults. Runtime systems use online or offline
scheduling mechanisms for task management of programs—own—system software
ones and user application ones. Since [1–4] it is expected that runtime system
provides a special session of tasks scheduling (offline or online during execution)
for the purposes of diagnostic of hardware conditions—recall Apple and Microsoft
system starting delays. Later for some systems that operate in domain of real-time
monitoring scheduling of tasks, critical in time of execution especially criticality of
hardware availability and efficiency of process scheduling become crucial. In turn,
testing itself becomes “hot” in terms of required time and coverage of hardware.
Thus in this chapter, we initially analyze simple sequences of testing of hardware
elements of computer systems. Further, we introduce a concept of transparent for
user application procedure of hardware testing. This enables to prove integrity of
computer system hardware, and guarantee it within a reasonable time, without delay
of service of execution of user tasks.
© Springer Nature Switzerland AG 2020
I. Schagaev et al., Software Design for Resilient Computer Systems,
https://doi.org/10.1007/978-3-030-21244-5_7
71
Testing, Checking, and Hardware
Syndrome
Abstract In previous chapters, we introduced the processes of checking and
testing, the first of the three main processes of Generalized Algorithm of Fault
Tolerance—GAFT. In this chapter, we further discuss the process of checking
hardware, at first software-based hardware-checking and at second hardware-based
checking. For the software-based hardware checking, we show what a
software-based test should include, when they are the preferred choice over
hardware-based checking schemes, and especially how such tests can be scheduled
in the system without interfering with ongoing real-time tasks. Further to support
handling of hardware-based checking, we introduce a new system condition
descriptor—so-called a syndrome, and illustrate how it can be used as a mechanism
to signal to the operating system the hardware condition, including manifestation of
detected error. We then show the steps the runtime system performs to eliminate the
fault and in case of permanent errors how the software can reconfigure the hardware
to exclude the faulty element. We also explain in which cases software has to adapt
to the new hardware topology. We start by explaining how software-based checks
can be used to detect hardware faults. Runtime systems use online or offline
scheduling mechanisms for task management of programs—own—system software
ones and user application ones. Since [1–4] it is expected that runtime system
provides a special session of tasks scheduling (offline or online during execution)
for the purposes of diagnostic of hardware conditions—recall Apple and Microsoft
system starting delays. Later for some systems that operate in domain of real-time
monitoring scheduling of tasks, critical in time of execution especially criticality of
hardware availability and efficiency of process scheduling become crucial. In turn,
testing itself becomes “hot” in terms of required time and coverage of hardware.
Thus in this chapter, we initially analyze simple sequences of testing of hardware
elements of computer systems. Further, we introduce a concept of transparent for
user application procedure of hardware testing. This enables to prove integrity of
computer system hardware, and guarantee it within a reasonable time, without delay
of service of execution of user tasks.
© Springer Nature Switzerland AG 2020
I. Schagaev et al., Software Design for Resilient Computer Systems,
https://doi.org/10.1007/978-3-030-21244-5_7
71