Lightweight virtualization implementation method and device

Abstract

The invention provides a lightweight virtualization implementation method and device, and belongs to the technical field of virtualization. According to the scheme, dependence on hardware resources is reduced by multiplexing an existing operating system, the complexity of virtualization is simplified, hardware isolated from the hardware is directly used by virtual machines, and high real-time performance of the virtual machines is guaranteed; from the perspective of a user, the scheme takes the whole virtualization process as an application program of a current operating system, and no resource consumption is increased after virtualization is started, so that sufficient light weight is achieved, and meanwhile, the performance requirement is also reduced; meanwhile, according to the scheme, hardware resources are directly used by the client through hardware isolation, so that the real-time requirement of the client can be ensured, and various real-time operating systems can be directly operated.

Description

Technical Field

[0001] The present invention belongs to the technical field of virtualization, and in particular relates to a lightweight virtualization implementation method and device. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Traditional virtualization solutions were born from Intel's x86 architecture and can be divided into two architecture types: Type I (bare metal architecture) and Type II (host architecture). They are mainly used in high-performance computing fields such as personal computers and servers with high computing performance.

[0004] Traditional virtualization solutions have the following defects: high requirements on device performance, difficult to apply to embedded environments with limited resources, and even unable to fully implement traditional virtualization architecture solutions in limited resource environments; because the client system (i.e. the operating system running inside the virtual machine) cannot directly use hardware resources, it needs to communicate with the hardware through the VMM (Virtual Machine Monitor: virtualization management program). In particular, the Type II architecture also needs to communicate with the hardware through the main client based on the VMM. Therefore, the real-time performance of each virtual machine cannot be guaranteed, and it is difficult to apply to environments with real-time requirements; it is usually difficult for the client to directly run various real-time operating systems or bare metal programs. Summary of the invention

[0005] The embodiments of the present invention provide a lightweight virtualization implementation method and device to solve the problems that the existing virtualization solutions cannot be applied in resource-constrained environments, the real-time performance of virtual machines cannot be guaranteed, and real-time operating systems or bare metal programs cannot be directly run.

[0006] According to a first aspect of an embodiment of the present invention, a lightweight virtualization implementation method is provided, which is applied to a device deployed with a pre-built user interaction tool, a system driver, and a virtual machine management firmware, including: In response to the enabling of the virtualization function, a client configuration file is loaded through a pre-built user interaction tool; wherein the user interaction tool runs on a main client operating system; the client configuration file includes hardware resources allocated to the main client and a plurality of sub-clients and a shared memory declaration for communication between the clients; Based on the configuration information in the client configuration file, the virtual machine management firmware is controlled by the system call to isolate the physical hardware resources of each client, and to provide each client with a shared memory for communication between clients, so as to realize the creation of clients and the communication between clients; wherein the virtual machine management firmware runs in the memory; When the virtualization function is enabled, the main client and the sub-client are both virtual machines, and when the virtualization function is disabled, the main client is an independent operating system.

[0007] Furthermore, the method directly provides hardware resources used by the client through hardware isolation.

[0008] Furthermore, the physical hardware resources of each client are isolated by controlling the virtual machine management firmware through system calls, specifically: a system call is made through a user interaction tool, the system call generates a super call through a system driver, the virtual machine management firmware is loaded into the memory through the super call to run, and the physical hardware is isolated to different clients through the loaded virtual machine management firmware.

[0009] Furthermore, the shared memory adopts a one-to-one model, and the communication between any two clients is accomplished by jointly declaring an independent shared memory.

[0010] Furthermore, the virtual machine management firmware operates at a specific processor privilege level. For the x86 architecture, the virtual machine management firmware operates at the kernel state privilege level of the root mode; for the ARM architecture, the virtual machine management firmware operates at the virtualization mode privilege level; for the RISC-V architecture, the virtual machine management firmware operates at the virtual machine monitor mode privilege level.

[0011] Furthermore, the virtual machine management firmware specifically performs the following processing: receiving configuration information and commands from the driver, and then processing them respectively according to the command type, wherein: For the enable and create commands, the corresponding CPU status is initialized according to the received configuration information, and the corresponding memory page table is created to implement the memory and CPU resource allocation and hardware isolation of different clients, and the configuration information of each client is managed through a linked list; For disable, delete, modify and query commands, corresponding processing is performed by querying the configuration information of the corresponding client and returning the processing results.

[0012] Furthermore, the user interaction tool specifically performs the following processing: Receive user command input; When the command input is an enable or create command, read and parse the preset configuration file, and send the parsing result and the corresponding command to the system driver to perform corresponding processing, and receive the processing result and display it; When the command input is a disable, delete or view command, the command is directly sent to the system driver to perform corresponding processing, and the processing result is received and displayed.

[0013] Furthermore, the system driver specifically performs the following processing procedures: receiving configuration information and commands from the user interaction tool; for enable and create commands, copying the content of the configuration information from the user space to the system space, and after verification, sending the verified configuration information and corresponding commands to the virtual machine management firmware for processing and returning the results; and, after successfully isolating the hardware resources, creating a corresponding maintenance node in a pre-built management linked list, and mapping the maintenance node back to the main client, so that the main client can maintain other clients; for query commands, finding the corresponding client information by directly traversing the existing management linked list, and then returning it to the user interaction tool.

[0014] Furthermore, the client runs an operating system including Linux, Android, Windows, a real-time operating system, and a bare metal program.

[0015] According to the second aspect of an embodiment of the present invention, a lightweight virtualization device is provided, comprising a hardware module and a software module, wherein the hardware module comprises a CPU, memory and IO devices; the software module comprises a host-client operating system, a user interaction tool, a system driver and a virtual machine management firmware, and a lightweight virtualization implementation method as described above is executed based on the software module.

[0016] One or more of the above technical solutions have the following beneficial effects: The present invention provides a lightweight virtualization implementation method and device. The scheme reduces the dependence on hardware resources by reusing the existing operating system (i.e., the main client operating system), simplifies the complexity of virtualization, and directly uses the hardware isolated by the hardware for the virtual machine, thereby ensuring the high real-time performance of each client (i.e., the virtual machine). From the user's perspective, the scheme of the present invention treats the entire virtualization process as an application of the current operating system. After starting the virtualization, there is no increase in the consumption of any resources, thereby achieving sufficient lightweight and also reducing performance requirements. The scheme of the present invention directly provides the client with hardware resources through hardware isolation, thereby ensuring the real-time requirements of the client, and can directly run various real-time operating systems. The advantages of the additional aspects of the present invention will be partially given in the following description, and partially will become obvious from the following description, or will be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0018] Figure 1 It is a schematic diagram of the overall framework of a lightweight virtualization implementation method described in an embodiment of the present invention; Figure 2 A basic flow chart of a lightweight virtualization implementation method described in an embodiment of the present invention; Figure 3 A schematic diagram of an example of running the virtualization method described in an embodiment of the present invention; Figure 4 The privilege levels corresponding to the virtual machine management firmware of different hardware platforms described in the embodiments of the present invention. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0020] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0021] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0022] like Figure 1 and Figure 2 As shown, the purpose of this embodiment is to provide a lightweight virtualization implementation method. The implementation of the method is based on a pre-built user interaction tool, a system driver, and a virtual management firmware, and specifically includes the following processing procedures: Step 1: In response to the enabling of the virtualization function, a client configuration file is loaded through a pre-built user interaction tool; wherein the user interaction tool runs on a main client operating system; the client configuration file includes hardware resources allocated to the main client and a plurality of sub-clients and a shared memory declaration for communication between clients; The user interaction tool is used as a human-computer interaction interface for users to manage virtual machines (ie, clients). The user interaction tool is used to view the status of existing virtual machines, create new virtual machines, delete existing virtual machines, and other functions.

[0023] The user interaction tool is essentially an ordinary application in the main client operating system, which is used to load the client configuration file provided by the user. Considering the permission restrictions of the operating system, most of its commands need to be sent to the system driver through system calls to be implemented.

[0024] In the specific implementation, Figure 3 As shown, the user enables or disables the virtualization function by executing specific commands using a user interaction tool in the main client operating system. After the user enables the virtualization function, the virtual machine management firmware automatically isolates the current system into a virtualized environment; after the user turns off the virtualization function, the user can restore to the original system.

[0025] In the virtualization result of the solution described in this embodiment, the virtual machine includes a main client and several sub-clients, wherein the main client serves as a virtualization management center, and its overall architecture is as follows: Figure 1 When virtualization is not enabled, only the main client is running, and the main client becomes an independent operating system, as shown in Figure 3 When virtualization needs to be enabled, the following needs to be executed in the main client: Figure 2 Related operations shown.

[0026] Compared with Type II, in the scheme described in this embodiment, the main client is essentially also a virtual machine, while the Host OS main client of Type II is not a virtual machine; compared with Type I, the main client and the sub-client of the scheme described in this embodiment can directly access hardware resources, while the client of Type I needs to go through the VMM to access the hardware.

[0027] User interaction tools, system drivers, and virtual machine management firmware are all independently usable executable programs. Due to the design of modern CPU instruction set architecture, various operations are divided into different permission levels. Therefore, operations with different permissions are processed separately through the above executable programs.

[0028] In the specific implementation, the main client is used for the entire virtualization management. Therefore, the user interaction tool, system driver, and virtual machine management firmware need to be installed on the main client to manage the virtual machine. Figure 2 shown.

[0029] It should be noted that virtualization management can be performed on any client, but in order to reduce complexity, the solution described in this embodiment limits the management operations in the sub-client. It is understandable that in more implementations, virtualization management can also be performed on other sub-clients besides the main client, which will not be described in detail here.

[0030] In one or more implementations, the virtualization implementation scheme described in this embodiment supports three mainstream chip instruction set architectures: x86, ARM, and RISC-V. The working positions of the user interaction tool, system driver, and virtual machine management firmware in the three chip instruction set architectures of x86, ARM, and RISC-V are shown in Figure 4. It should be noted here that in the three chip instruction set architectures, the user interaction tool, system driver, and virtual machine management firmware have the authority to perform corresponding operations only when they run at the corresponding privilege level.

[0031] The virtualization method can be directly deployed on a hardware device and also supports the reuse of an existing operating system of the device.

[0032] After virtualization is started, the user can use the corresponding commands of the user interaction tool in the main client operating system to perform operations such as creating a new client, viewing the status of an existing client, or deleting an unnecessary client. Figure 4 As shown, a specific instance after creating a new client is shown.

[0033] In the solution described in this embodiment, the entire virtualization implementation solution is based on the existing operating system of the device, and the management of all client machines is performed in the master client.

[0034] In a specific implementation, the user interaction tool specifically performs the following processing: Receive user command input; When the command input is an enable or create command, read and parse the preset configuration file, and send the parsing result and the corresponding command to the system driver to perform corresponding processing, and receive the processing result and display it; When the command input is a disable, delete or view command, the command is directly sent to the system driver to perform corresponding processing, and the processing result is received and displayed.

[0035] Specifically, the user interaction tool is an executable program in the user space for human-computer interaction, which provides commands such as enable, disable, create, delete, and view for virtualization management.

[0036] For enabling and creating commands, the configuration file is read and parsed, and the format of the parsed content and the legality of the configuration items are preliminarily verified, and then the verified content is sent to the system driver, and the return result of the system driver is received and displayed to the user. The configuration file is essentially a text file that is easy for users to read and write, which records the hardware resources such as memory, CPU, various peripherals, etc. that the virtual machine needs to use, as well as the shared memory declaration for communication between different virtual machines.

[0037] For sub-commands such as disable, delete, and view, it directly sends the corresponding command to the driver, waits for the driver to return the corresponding result, and then displays the returned result to the user; It should be noted here that since virtualization operations are privileged operations, and user interaction tools are essentially user-mode tools, they do not have virtualization permissions (the permissions of different architectures are as follows Figure 4 As shown in Figure 1, all operations must be handled by the system driver through system calls. The above reason is that the chip instruction set architecture design does not allow the user space privilege level to directly switch to the virtual machine management privilege level, such as Figure 4 As shown, the user interaction tool, system driver, and virtual machine management firmware in the solution described in this embodiment correspond to three different privilege levels: user privilege level, system privilege level, and virtual machine privilege level, respectively.

[0038] Step 2: Based on the configuration information in the client configuration file, the virtual machine management firmware is controlled by the system call to isolate the physical hardware resources of each client, and to provide each client with a shared memory for communication between clients, so as to realize the creation of the client and the communication between the clients; wherein the virtual machine management firmware runs in the memory; When the virtualization function is enabled, the main client and the sub-client are both virtual machines, and when the virtualization function is disabled, the main client is an independent operating system.

[0039] In a specific implementation, the physical hardware resources of different clients are isolated by controlling the virtual machine management firmware through system calls, specifically: a system call is made through a user interaction tool, the system call generates a super call through a system driver, the virtual machine management firmware is loaded into the memory through the super call to run, and the physical hardware is isolated to different clients through the loaded virtual machine management firmware.

[0040] Among them, the system driver is used to load the virtual machine management firmware and respond to interactive commands from user interactive tools. It also manages and maintains the basic information of each client. The system driver is the kernel module of the operating system and is loaded into the operating system kernel by the user. For virtualization-related processing, it requires a special privilege level. Therefore, some commands need to be sent to the virtual machine management firmware through hypercalls to implement.

[0041] Furthermore, the system driver specifically performs the following processing: receiving configuration information and commands from a user interaction tool; For the enable and create commands, the content of the configuration information is copied from the user space to the system space, and after verification, the verified configuration information and the corresponding commands are sent to the virtual machine management firmware.

[0042] Specifically, verification processing is performed on the configuration information or command received from the user interaction tool; After the verification is completed, for the enable and create commands, the content of the configuration information is copied from the user space to the system space, and then the version, identifier, and availability of the description resource of the configuration information are further verified. After the verification passes, the configuration information of each client is managed in the form of a linked list; The verified configuration information is then sent to the virtual machine management firmware, which allocates hardware resources to each client and performs hardware isolation operations based on the configuration information. It should be noted here that for the creation, enablement, and disablement commands, their corresponding operations require higher permissions (see the permission classification of different architectures for details). Figure 4 ), therefore, the driver loads the virtual machine management firmware into memory for execution, and then sends certain privileged operations to the virtual machine management firmware through hypercalls for processing and returns the results.

[0043] After successfully isolating the hardware resources, the system driver needs to create a corresponding maintenance node and map the maintenance node back to the main client so that the main client can maintain other clients.

[0044] For query commands, the existing management linked list can be directly traversed to find the corresponding client information, and then returned to the user interaction tool.

[0045] In specific implementations, the virtual machine management firmware is used to isolate physical hardware resources to different clients, ensuring that different clients only use their own visible hardware resources. The virtual machine management firmware is essentially a special binary code that is loaded into memory and run by the system driver.

[0046] In the specific implementation, the hardware isolation function of the virtual machine management firmware is the core of the entire virtualization solution. It implements the hardware isolation function by using the hardware virtualization features provided by the processor. Therefore, the implementation method is different for different hardware platforms. Figure 4 As shown, the virtual machine management firmware works at a specific processor privilege level. For the x86 architecture, the virtual machine management firmware works at the kernel state Ring0 privilege level of the root mode Root Mode; for the ARM architecture, the virtual machine management firmware works at the virtualization mode EL2 privilege level; for the RISC-V architecture, the virtual machine management firmware works at the virtual machine monitor mode Hypervisor Mode privilege level.

[0047] In a specific implementation, the virtual machine management firmware is used to receive configuration information and commands from a system driver; for enable and create commands, different client hardware resources are allocated and hardware isolating is performed according to the configuration information; wherein the configuration information of each client is managed in the form of a linked list; for disable, delete, modify and query commands, the client to be operated is determined by traversing the linked list, and the corresponding client is processed accordingly; Specifically, the virtual machine management firmware is essentially an executable program that receives configuration information and commands from the driver and then processes them according to the command type, where: For the enable and create commands, the corresponding CPU status is initialized according to the received configuration information, and the corresponding memory page table is created to implement the memory and CPU resource allocation and hardware isolation of different clients, and the configuration information of each client is managed through a linked list; For example, taking memory isolation as an example, through the extended page table or nested page table technology supported by the hardware virtualization characteristics of the processor, the virtual machine management firmware can directly set the memory mapping of the virtual machine to ensure that each virtual machine can only access its own memory space without going through the system driver.

[0048] It is understandable that the allocation of hardware resources and hardware isolation, in addition to memory and CPU, may also include other hardware devices such as I / O devices, storage devices, graphics cards, etc.

[0049] It should be noted that when a new guest is created or deleted, the virtual machine management firmware will be updated and synchronized among all existing virtual machines. The reason is that when performing hardware isolation, the virtual machine management firmware needs to suspend all other guests to ensure security and reliability.

[0050] For commands such as disable, delete, modify, and query, the virtual machine management firmware traverses the linked list, queries the configuration information of the corresponding client, performs corresponding processing, and returns the processing results.

[0051] In more embodiments, the virtual machine management firmware is also used to manage shared memory between clients for communication between clients, wherein the shared memory is defined in a configuration file of each client.

[0052] Furthermore, when creating a client, the virtual machine management firmware only initializes the resources that the client can use according to the configuration information in the configuration file. When the client accesses non-isolated resources, an exception will occur.

[0053] In a specific implementation, the virtual machine management firmware also provides shared memory for communication between different clients. The shared memory adopts a one-to-one model, that is, when any two clients communicate, they need to jointly declare a shared memory for communication.

[0054] Specifically, the shared memory in the solution described in this embodiment is defined by the configuration files corresponding to each client. When two clients define the same shared memory in the configuration files, the two clients can communicate through the shared memory.

[0055] It should be noted here that although Type I and Type II architectures also have shared memory, their shared memory is directly defined by the VMM, and users need to configure the VMM to implement shared memory.

[0056] The shared memory configuration of the solution described in this embodiment can meet the following application requirements: The main client is usually a non-real-time operating system, while other clients are real-time operating systems. In this application, the main client, as a user interface, can handle most tasks, while real-time tasks will be handed over to clients with real-time operating systems. In this case, the relevant configuration information and processing results are realized through communication between clients. For example, in industrial control, the main client provides the UI interface, while the client with a real-time operating system is responsible for processing various industrial controls with high real-time requirements. The control parameters and control results need to be shared with the main client for users to view.

[0057] Furthermore, the shared memory setting described in this embodiment also allows different clients to share the same device.

[0058] In one or more implementations, the system running on the client may be a traditional Linux, Android or other system, or various real-time operating systems. At the same time, since the solution described in this embodiment directly isolates physical resources, bare metal programs may also be run directly.

[0059] In one or more embodiments, a lightweight virtualization device is provided, including a hardware module and a software module, wherein the hardware module includes a CPU, memory, and IO devices; the software module includes a host-client operating system, a user interaction tool, a system driver, and a virtual machine management firmware, and a lightweight virtualization implementation method as described above is executed based on the software module.

[0060] In a specific implementation, when an operating system already exists on a device, the existing operating system can be directly reused as the main client, and the user interaction tools, drivers, and virtual machine management firmware can be installed as a toolkit into the existing operating system for use.

[0061] When there is no operating system on the device, pre-built user interaction tools, drivers, virtual machine management firmware and client configuration files can be packaged into the device, and then the current virtualization solution can be directly deployed through the system installation tool. After deployment, a structure of a main client and multiple client systems is formed.

[0062] In this embodiment, whether directly deploying or reusing an existing operating system, the user needs to manage all clients (including adding, deleting, modifying, and checking) and enable or disable the virtualization function in the main client.

[0063] Those skilled in the art will appreciate that the units, i.e., algorithm steps, of the various examples described in the present embodiment can be implemented in electronic hardware or in a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A lightweight virtualization implementation method, characterized in that: It is applied to devices deployed with pre-built user interaction tools, system drivers, and virtual machine management firmware, including: In response to the enabling of the virtualization function, a client configuration file is loaded through a pre-built user interaction tool; wherein the user interaction tool runs on a main client operating system; the client configuration file includes hardware resources allocated to the main client and a plurality of sub-clients and a shared memory declaration for communication between the clients; Based on the configuration information in the client configuration file, the virtual machine management firmware is controlled by the system call to isolate the physical hardware resources of each client, and to provide each client with a shared memory for communication between clients, so as to realize the creation of clients and the communication between clients; wherein the virtual machine management firmware runs in the memory; When the virtualization function is enabled, the main client and the sub-client are both virtual machines, and when the virtualization function is disabled, the main client is an independent operating system.

2. A lightweight virtualization implementation method as claimed in claim 1, characterized in that: The method directly provides hardware resources used by the client through hardware isolation.

3. A lightweight virtualization implementation method as claimed in claim 1, characterized in that: The method of isolating the physical hardware resources of each client by controlling the virtual machine management firmware through system calls is specifically: a system call is made through a user interaction tool, the system call generates a super call through a system driver, the virtual machine management firmware is loaded into the memory through the super call and runs, and the physical hardware is isolated to different clients through the loaded virtual machine management firmware.

4. A lightweight virtualization implementation method as claimed in claim 1, characterized in that: The shared memory adopts a one-to-one model, and the communication between any two clients is accomplished by jointly declaring an independent shared memory.

5. A lightweight virtualization implementation method as claimed in claim 1, characterized in that: The virtual machine management firmware works at a specific processor privilege level. For the x86 architecture, the virtual machine management firmware works at the kernel state privilege level of the root mode; for the ARM architecture, the virtual machine management firmware works at the virtualization mode privilege level; for the RISC-V architecture, the virtual machine management firmware works at the virtual machine monitor mode privilege level.

6. A lightweight virtualization implementation method as claimed in claim 1, characterized in that: The virtual machine management firmware specifically performs the following processing: receiving configuration information and commands from the driver, and then processing them respectively according to the command type, wherein: For the enable and create commands, the corresponding CPU status is initialized according to the received configuration information, and the corresponding memory page table is created to implement the memory and CPU resource allocation and hardware isolation of different clients, and the configuration information of each client is managed through a linked list; For disable, delete, modify and query commands, corresponding processing is performed by querying the configuration information of the corresponding client and returning the processing results.

7. A lightweight virtualization implementation method as claimed in claim 1, characterized in that: The user interaction tool specifically performs the following processing: Receive user command input; When the command input is an enable or create command, read and parse the preset configuration file, and send the parsing result and the corresponding command to the system driver to perform corresponding processing, and receive the processing result and display it; When the command input is a disable, delete or view command, the command is directly sent to the system driver to perform corresponding processing, and the processing result is received and displayed.

8. A lightweight virtualization implementation method as claimed in claim 1, characterized in that: The system driver specifically performs the following processing: receiving configuration information and commands from the user interaction tool; for enable and create commands, copying the content of the configuration information from the user space to the system space, and after verification, sending the verified configuration information and corresponding commands to the virtual machine management firmware for processing and returning the results; And, after the hardware resources are successfully isolated, a corresponding maintenance node is created in the pre-built management chain list, and the maintenance node is mapped back to the main client, so that the main client can maintain other clients; For query commands, the corresponding client information is found by directly traversing the existing management linked list, and then returned to the user interaction tool.

9. A lightweight virtualization implementation method as claimed in claim 1, characterized in that: The client operating system types include Linux, Android, Windows, real-time operating systems, and bare metal programs.

10. A lightweight virtualization device, characterized in that: It includes hardware modules and software modules, wherein the hardware modules include CPU, memory and IO devices; the software modules include host-client operating systems, user interaction tools, system drivers and virtual machine management firmware, and a lightweight virtualization implementation method as described in any one of claims 1 to 9 is executed based on the software modules.

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