AUTOSAR compliant multi-core RTOS(Part-3)
Published: 2024-02-11 18:46:37

Dear readers,
My name is Sadashiv Balawad and I am working as Junior Software Engineer at Luxoft India. Luxoft gave me many opportunities to work on various projects, which inspired me to talk about the importance of multicore Real Time Operating Systems(Part-3)

**FORMAL METHODS FOR REAL-TIME SYSTEMS**
**Introduction**
Formal techniques ensure machine self belief, and the emergence of latest software equipment has brought about their usability. We study in this chapter the existing formal verification strategies in the literature, specializing in their use for verifying the utility’s schedulable and actual-time running structures. We rely on the two most popular households of formal strategies: theorem proving and version-checking. In theorem proving, we examine infinite systems laid out in the suitable mathematical good judgment to confirm the righties and offer proof. On the opposite hand, in model-checking, we examine whether or not the
favored belongings is happy via exploring the whole country space of the finite constructed model. It is an automatic and efficient approach that also can cope with the problem of kingdom area explosion when the quantity of states grows to infinity with growing variables and their awesome values in addition to components.

**Formal verification methods**
Testing is extensively used in exercise, even though it is simply not possible to apply it in extraordinarily crucial structures wherein test records could reason damage if errors are made earlier than actual deployment. Another solution is to simulate the conduct of the system on a laptop. The simulation does now not paintings at once at the actual gadget however on a model. A version represents an abstract illustration of the actual device, commonly written the usage of mathematics or good judgment. Both testing and simulation are widely used in commercial programs,
and their use has demonstrated to be very beneficial. A disadvantage, but, is that it isn't always commonly feasible to simulate or test all viable scenarios or behaviors of a given machine.
Here are some examples where trying out and simulation failed. The Air France Flight 447 crash in June 2009 caused the loss of life of the people on board. When the plane became flying from Rio de Janeiro to Paris, the hurricane triggered the airspeed sensors to freeze, leading the autopilot to disconnect. The pilots misinterpreted the noise, main the aircraft to ram into the ocean. The worst is knowing that the crash could have been avoided. In
August 2005, The Boeing 777-two hundred of Malaysia Airlines Flight 124 unexpectedly and with out caution climbed better than anticipated. The group faced a supposedly impossible situation where the stall and overspeed signs became on simultaneously. The plane landed approximately 18 minutes into the flight, and the failure came about in its air records inertial reference unit. One of the 2 accelerators controlling the airspeed failed, and due to
a software anomaly, the second one used incorrect statistics from the first accelerator. Another instance is the failure of the Computer Aided Dispatch (CAD) in the London ambulance service. The inquiry group’s investigations display that the gadget and the resilience of the hardware had been no longer completely examined earlier than implementation.
Formal verification, in assessment to checking out and simulation, permits the exhaustive investigation the use of static analysis primarily based on mathematical fashions to verify the accuracy
of hardware or software behavior. Accidents can then be avoided if the structures are established and analyzed mathematically. Two categories exist, deductive strategies based totally on theorem proving and automatic strategies primarily based on version-checking.

**Theorem-based methods**
Formal theorem proving is one of the quickest developing regions in latest years, that verifies the correctness of the device’s homes through mathematical reasoning. With the new effective equipment of theorem provers, unsolvable problems several decades ago are being handled these days, and new demanding situations are emerging. Many fields, which include computer technological know-how, biomedical, economics, device gaining knowledge of, and artificial intelligence, have efficaciously used theorem provers. It gives a statement from a logical set of axioms or hypotheses to check a gadget’s houses defined with mathematical common sense. Theorem provers may be divided into two categories:

**- Interactive Theorem Provers (ITPs),** 
Referred to as proof-assistants : this method lets in proofs to be built with a reliance on user guidance. It entails human interaction with the device within the formal evidence development process .Coq and Isabelle/HOL  are a number of the most well-known present gear Their overall performance is extraordinary, and that they formalized and proved many theorems in the first hundred theorem listing

**- Automated Theorem Provers (ATPs):**
: This kind is composed in constructing the
proofs mechanically via the tool with out consumer intervention primarily based on a description of the device to be verified, a set of axioms, and inference rules. Current ATP structures can clear up non-trivial troubles, consisting of the Robbins trouble [ solved by the EQP automated theorem proving program for first-order equational common sense In practice, the complexity of most issues is considerable and can not be solved inside useful resource limits. Thus a massive issue of ATP studies is developing more effective systems which can resolve troubles in the identical aid constraints
Theorem-proving techniques have barriers, which include the sluggish procedure of building proof, in spite of automated provers. In addition, most theorems do not aid graphical and visualization gear, and common sense isn't always sensible as a language. The technique requires a high-degree of understanding on the consumer’s component, specially for ITPs that require heavy InterMation and lots of energy. These drawbacks are consequently an impediment to adopting theorem proving while handling complicated structures. However, destiny works on this path
continue to enhance faster and extra efficient provers and cause them to greater suitable for the commercial region through trying to combine specific strategies.
I will try to explain more this topic in next part

Thank you