Task Online Update System and Method under Memory Constrained Conditions of a Spacecraft Real-Time System

Abstract

A task online update system under the condition of memory limitation in a spacecraft real-time system, including a ground maintenance module for system symbol information, a ground generation module for injection data packets, and an on-board processing module for injection data packets; the ground maintenance module for system symbol information checks whether the injection program conflicts with the spacecraft memory allocation; the ground generation module for injection data packets encapsulates the header information of the program to be injected, program running information, task attribute information, and executable binary files into an injection data packet file; the on-board processing module for injection data packets, after receiving the instruction to parse the injection program, parses the injection data packet file in the idle task according to the protocol format, and after the parsing is completed, adds a new task to the scheduling table or replaces an original task. The present invention also provides an online update method. The present invention enables the spacecraft to have the task-level system expansion ability, realizes the addition or replacement of tasks, upgrades the on-board software of the spacecraft in a timely manner according to the task requirements, and endows the spacecraft with new functions.

Description

Technical Field

[0001] The present invention relates to a task online update system and method under the condition of limited memory in a spacecraft real-time system, belonging to the field of spacecraft software design. Background Art

[0002] Traditional on-orbit maintenance methods for spacecraft on-board software rely on "hook" functions preset during software design. After injecting the modified code patch into the injection area, by enabling the "hook", the program pointer jumps to the corresponding function in the injection area to execute, thereby realizing the on-orbit replacement of function capabilities. This method usually presets hooks at positions where application tasks, important underlying function functions, etc. may need to be replaced on-orbit. It has disadvantages such as the number of hooks being limited by the positions and numbers of pre-buried hook functions, poor expandability, complex injection program generation methods, and being prone to errors.

[0003] For major change requirements such as adding or replacing tasks, the traditional method is to re-make a complete executable binary file, which is uploaded and written into non-volatile memories such as EEPROM and NOR Flash after uploading. After the system restarts, the new program runs. This method requires a relatively large amount of data to be uploaded, occupies a lot of spacecraft TT&C resources, and the entire update process takes a long time, which is not conducive to large-scale application deployment.

[0004] Ordinary embedded systems such as smart phones use the dynamic linker provided by the operating system and use dynamic link library technology to achieve online update of the software system. This technology usually takes the object file as the target of online program update, and has disadvantages such as large object files, long parsing time, and the system cannot be used during update, and is not suitable for being applied to the memory resource-limited and strongly real-time spacecraft on-board computer. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: overcoming the deficiencies of the prior art, and providing a task online update system and method under the condition of limited memory in a spacecraft real-time system.

[0006] The technical solution of the present invention is as follows:

[0007] A task online update system under the condition of limited memory in a spacecraft real-time system includes a ground maintenance module for system symbol information, a ground generation module for injection data packets, and an on-board processing module for injection data packets;

[0008] The ground maintenance module for system symbol information checks whether the program to be injected conflicts with the memory allocation of the spacecraft on-board software to ensure the consistency of the ground system symbol table and the spacecraft on-board software symbol table, and outputs the program to be injected that has been checked and has no conflict to the ground generation module for injection data packets;

[0009] The injection data packet ground generation module is responsible for designing the format of the injection data packet, extracting the header information, program running information, task attribute information, and executable binary file from the program to be injected, encapsulating them in the format, and generating an injection data packet file; the injection data packet file is uploaded to the on-board software storage area of the spacecraft through the data transmission system.

[0010] After the spacecraft receives the parsing injection program instruction uploaded from the ground, the on-board processing module of the injection data packet parses the injection data packet file in the idle task according to the protocol format without affecting the normal execution of the system task. After parsing, a new task will be added to the scheduling table or replace an original task.

[0011] Preferably, the implementation method of the system symbol information ground maintenance module is as follows:

[0012] (1) Extract the global variables and non-static function symbol address information from the executable file in the original state of the spacecraft to form the ground system symbol address mapping table in the initial state, and form an available memory table in combination with the system memory allocation requirements;

[0013] (2) When there is a program injection requirement, execute step (3);

[0014] (3) Compile and link the source code of the program to be injected to generate the executable file of the program to be injected. Check whether there is a conflict with the on-board software memory allocation of the spacecraft according to the allocation of the text segment and data segment of the executable file. If there is no conflict, enter step (4); if there is a conflict, enter step (5);

[0015] (4) The injection data packet ground generation module generates an injection data packet file according to the executable file, updates the ground system symbol address mapping table and the available memory table, and ends;

[0016] (5) Adjust the compilation addresses of the text segment and data segment of the program to be injected, recompile to generate the injection program, and then execute step (3).

[0017] Preferably, the method for generating the executable file of the program to be injected is as follows:

[0018] The compiler compiles the source code of the program to be injected in the original cross-compilation environment to generate an object file with relocation information. If there are multiple generated object files, they need to be combined into one object file;

[0019] When the program to be injected calls the functions and variables of the original on-board system, undefined function and variable symbol information will be formed in the compiled object file;

[0020] The injection program compiler searches and extracts the undefined function and variable symbol information in the original system symbol table and writes it into the link parameter file;

[0021] Under the cross - compilation environment, the linker receives the compilation and linking address parameters of the text segment and data segment specified by the user, links the target file with the link parameter file, and generates an executable file of the program to be injected.

[0022] Preferably, when the target file is linked with the link parameter file, the binding of undefined function, variable symbols and addresses is realized.

[0023] Preferably, in the injection data packet format, the header information includes the program - to - be - injected flag, protocol version, length, checksum; the program running information includes the start address and size of the text segment, the start address and size of the data segment, the start address and size of the bss segment, the number of tasks; the task attribute information includes the task flag, priority, stack size, task type, scheduling start point information; the executable binary file includes the text segment content and the data segment content.

[0024] Preferably, the on - ground generation module of the injection data packet includes an injection program extractor, a task running attribute reader, and an injection data packet packaging unit;

[0025] The injection program extractor is responsible for extracting the start address and size of the text segment, the start address and size of the data segment, the start address and size of the bss segment from the executable file of the program to be injected after compilation, and the executable binary file including the text segment content and the data segment content;

[0026] The task running attribute reader is responsible for providing the task attribute information, the number of tasks and the setting of the header information required during the running of the program to be injected to the personnel who generate the injection program and obtaining the set information, and generating the running information of the program to be injected according to the number of tasks, the start address and size of the text segment, the start address and size of the data segment, and the start address and size of the bss segment extracted by the injection program extractor;

[0027] The injection data packet packaging unit is responsible for packaging the header information, the executable binary file of the program to be injected, the task attribute information, and the running information of the program to be injected into an injection data packet file that meets the injection format.

[0028] Preferably, the implementation method of the on - satellite processing module of the injection data packet is as follows:

[0029] (1) When the idle task judges whether the parsed injection program instruction of the on - ground upload is valid, if it is invalid, it exits and continues to execute other operations of the idle task, otherwise it executes step (2);

[0030] (2) Check the injection data packet file according to the protocol format. If the check fails, it exits and continues to execute other operations of the idle task, otherwise it executes step (3);

[0031] (3) Extract the number of tasks and program running address information from the injected data packet file, move them to the specified address, complete the initialization of the text segment, data segment, and bss segment, and establish the running environment of the injected program;

[0032] (4) Determine whether all tasks have completed attribute parsing. If so, exit; if not, determine whether the current task name is the same as the replacement name. If the names are the same, enter step (5) to create a new task; otherwise, enter step (6) to replace the original task;

[0033] (5) Create a task based on the stack size and task ID assigned to the task. After creation, add the new task to the task queue, update the scheduling time sequence table, and then return to (4) to continue performing the attribute parsing of the next task;

[0034] (6) Find the ID of the task to be replaced, change its entry function address, and then return to (4) to continue performing the attribute parsing of the next task.

[0035] Preferably, the on-board processing module of the injected data packet completes the update of the scheduling table in the control cycle interrupt handler, so that the system performs task scheduling and operation according to the new time sequence.

[0036] A method for online task update under the condition of memory limitation in a spacecraft real-time system, including:

[0037] The system symbol information ground maintenance module checks whether the program to be injected conflicts with the memory allocation of the on-board software of the spacecraft, and outputs the executable file obtained after compiling and linking the program to be injected that has been checked and has no conflicts to the ground generation module of the injected data packet;

[0038] The ground generation module of the injected data packet extracts the program running information and executable binary file from the program to be injected, and encapsulates them in the format of the injected data packet in combination with the header information and task attribute information filled in on the ground to generate an injected data packet file;

[0039] The injected data packet file is uploaded to the spacecraft through the data transmission system;

[0040] The ground sends a parsing injected program instruction to the on-board software of the spacecraft;

[0041] After the spacecraft receives the parsing injected program instruction uploaded from the ground, the on-board processing module of the injected data packet parses the injected data packet file in the idle task according to the protocol format without affecting the normal execution of the system tasks. After parsing, add a new task to the scheduling table or replace a certain original task.

[0042] Preferably, in the injection data packet format, the injection program header information includes the injection program flag, protocol version, length, and checksum; the program running information includes the text segment starting address and size, the data segment starting address and size, the bss segment starting address and size, and the number of tasks; the task attribute information includes the task flag, priority, stack size, task type, and scheduling starting point information; the executable binary file includes the text segment content and the data segment content.

[0043] The beneficial effects of the present invention compared with the prior art are:

[0044] (1) Compared with the prior art that implements the program injection function on-orbit by modifying the pre-embedded hook function or the entry address of the replaced function, the present invention is aimed at the task-level program online update system, which realizes the modification of software functions by realizing the online replacement and modification of task functions, and has the advantages of unlimited number of tasks and convenient use. The on-board program verifies the injected program and then analyzes it, and can complete the replacement and addition of tasks. This method provides a new method for the on-orbit upgrade of software functions on spacecraft in the future.

[0045] (2) The injection data packet file generated by the present invention has a concise protocol format and a small amount of data. The system parses the injection data in the idle task without affecting the normal execution of the system task. After the update is completed, the new task can be executed without restarting.

[0046] (3) The injection program protocol format designed by the present invention has low requirements on the memory space of the embedded system and does not need to store information such as symbol tables. The injection program can utilize the original functions such as functions and variables provided by the system and is suitable for resource-constrained spacecraft real-time systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 Provides ground maintenance procedures for system symbol information;

[0048] Figure 2 Generate process for injecting data packet files;

[0049] Figure 3 Parse and inject data packet files into the on-board program; DETAILED DESCRIPTION

[0050] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0051] On-orbit program injection is the main means for spacecraft such as satellites to repair problems and update functions on orbit. The task online update system designed by the present invention provides a new method for injecting programs on orbit, which can realize the update of the application task functions of spacecraft and provide support for the on-orbit maintenance of spacecraft. The present invention compiles the upload program in combination with relevant information of the original system program to form an executable program, adds task operation-related information that meets the loading file format, and forms an injection data packet file for the on-board software of the spacecraft to parse and execute new function tasks after parsing.

[0052] The present invention includes a ground maintenance module for system symbol information, a ground generation module for injection data packets, and an on-board processing module for injection data packets.

[0053] The ground maintenance module for system symbol information checks whether the program to be injected conflicts with the memory allocation of the on-board software of the spacecraft to ensure the consistency between the ground system symbol table and the on-board software of the spacecraft, and compiles and links the program to be injected that has been checked and has no conflicts to generate an executable file and outputs it to the ground generation module for injection data packets.

[0054] The ground generation module for injection data packets is responsible for designing the format of the injection data packet, extracting program operation information and executable binary files from the executable file of the program to be injected, and encapsulating them in accordance with the format in combination with the header information and task attribute information filled in on the ground to generate an injection data packet file; the injection data packet file is uploaded to the spacecraft through the data transmission system.

[0055] The on-board processing module for injection data packets, after the spacecraft receives the instruction to parse and inject the program from the ground, parses the injection data packet file in the idle task in accordance with the protocol format without affecting the normal execution of the system tasks. After parsing, a new task is added to the scheduling table or an original task is replaced.

[0056] As Figure 1 shown, the ground maintenance module for system symbol information of the system of the present invention realizes the following steps:

[0057] (1) Extract the global variables and non-static function symbol address information from the on-board executable file in the original state of the spacecraft to form an initial ground system symbol address mapping table (i.e., a map file in the symbol-address format), and form an available memory table in combination with the system memory allocation requirements;

[0058] (2) When there is a program injection requirement, execute step (3);

[0059] (3) Compile and link the source code of the upload program to generate an executable file of the upload program. Check for conflicts in available memory allocation in combination with the allocation of the text segment and data segment of the executable file of the injection program. If there is no memory allocation conflict, enter step (4); if there is a memory allocation conflict, enter step (5);

[0060] The generation process of the executable file of the upper injection program is as follows:

[0061] (S1) Through the compiler, compile the source code of the injection program in the original cross-compilation environment to generate an object file with relocation information. If there are multiple generated object files, the compiler needs to be used to synthesize one object file;

[0062] (S2) The injection program compiler extracts the undefined function and variable symbol information from the object file; when the injection program calls the functions and variables of the original system, the undefined symbol information will be formed in the compiled object file;

[0063] (S3) The injection program compiler searches and extracts the undefined symbol information in the original system symbol table and writes it into the link parameter file; when linking the object file to be injected with the link parameter file, the binding of the undefined symbol and the address is realized;

[0064] (S4) Through the linker, receive the compilation and link address parameters of the text segment and data segment specified by the user, and link the relocatable object file into the injection program executable file in combination with the above link parameter file, and end.

[0065] (4) The injection data packet ground generation module generates an injection data packet file according to the executable file, updates the ground system symbol address mapping table and the available memory table, and ends;

[0066] (5) Adjust the compilation addresses of the text segment and data segment of the program to be injected, recompile to generate the injection program, and then execute step (3).

[0067] As Figure 2 shown, the injection data packet ground generation module of the present invention realizes the following steps:

[0068] (1) Through the injection program extractor, extract the start address and size of the text segment, the start address and size of the data segment, the start address and size of the bss segment, and the executable binary file including the text segment content and data segment content from the compiled injection program executable file.

[0069] (2) Through the task running attribute reader, the injection program generator sets the attribute information and header information required during the running of the program to be injected; after setting, generate the header information, including the running information of the program to be injected such as the number of tasks, the start address and size of the text segment, the start address and size of the data segment, and the start address and size of the bss segment extracted by the injection program extractor; and the task attribute information including the task flag, priority, stack size, task type, and scheduling start point information.

[0070] (3) The injection data packet packaging unit packages the header information, the executable binary file of the program to be injected, and the relevant attribute information into an injection data packet file that meets the injection format. The packaging protocol is as follows:

[0071]

[0072] As Figure 3 shown, the on-orbit processing module of the injection data packet of the present invention is implemented as follows:

[0073] (1) In the idle task, judge whether the injection program instruction is valid. If it is invalid, exit and continue to execute other operations of the idle task. Otherwise, execute step (2);

[0074] (2) Verify the injection program according to the protocol format. If the verification fails, exit and continue to execute other operations of the idle task. Otherwise, execute step (3);

[0075] (3) Extract the number of tasks and the program running address information, move the text segment and data segment data of the injection program to the specified address, initialize the bss segment, and establish the running environment of the injection program;

[0076] (4) Parse the attributes of each task one by one to judge whether the task name is the same as the replacement name. After all tasks are processed, exit and continue to execute other operations of the idle task. If they are the same, perform the operation of creating a new task and execute step (5). Otherwise, perform the operation of replacing the original task and execute step (6);

[0077] (5) Create a task according to the attributes such as the stack size assigned to the task and the task ID. After creation, add the new task to the task queue and update the scheduling time sequence table. Return to (4) and continue to execute the parsing of the next task attribute;

[0078] (6) Find the ID of the task to be replaced and change its entry function address. Return to (4) and continue to execute the parsing of the next task attribute.

[0079] The on-orbit processing module of the injection data packet completes the update of the scheduling table in the control cycle interrupt handler, so that the system schedules and runs tasks according to the new time sequence.

[0080] A method for online updating of tasks under the condition of limited memory in a spacecraft real-time system includes:

[0081] The ground maintenance module of the system symbol information checks whether the program to be injected conflicts with the memory allocation of the spacecraft on-orbit software, and outputs the program to be injected that is checked to have no conflict to the ground generation module of the injection data packet;

[0082] The injection data packet ground generation module extracts the header information, program running information, task attribute information, and executable binary file from the program to be injected, encapsulates them in the format of an injection data packet, and generates an injection data packet file;

[0083] The injection data packet file is uploaded to the spacecraft through the data transmission system;

[0084] The ground sends a parsing injection program instruction to the spacecraft;

[0085] After receiving the parsing injection program instruction uploaded from the ground, the on-board processing module of the injection data packet parses the injection data packet file in the idle task according to the protocol format without affecting the normal execution of the system task. After parsing, a new task will be added to the scheduling table or replace an original task.

[0086] The present invention proposes a task online update system and method applicable to a real-time system with limited memory resources, which can realize functions such as online replacement and addition of system tasks without affecting the operation of the original tasks. The present invention combines the uploaded program with the relevant information of the original system program to compile an executable program, adds the task running related information that meets the loading file format, forms a binary injection program, and is used for the on-board software to parse and execute the tasks with new functions. The present invention includes a system symbol information ground maintenance module, an injection data packet ground generation module, and an on-board processing module of the injection data packet to jointly complete the task online update function. The designed uploaded program format uses the system symbol table information generated in the original compilation environment to generate an executable file after linking. This method makes full use of the processing power of the ground computer, and only uploads the binary file of the newly added code as the injection program, reducing the program injection volume.

[0087] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A task online update system under memory-constrained conditions for a spacecraft real-time system, characterized in that, It includes a ground maintenance module for system symbol information, a ground generation module for injection data packets, and an on-board processing module for injection data packets; The ground maintenance module for system symbol information checks whether the program to be injected conflicts with the on-board software memory allocation of the spacecraft to ensure the consistency between the ground system symbol table and the on-board software symbol table of the spacecraft, and outputs the program to be injected that has been checked and has no conflicts to the ground generation module for injection data packets; The ground generation module for injection data packets is responsible for designing the format of the injection data packet, extracting the header information, program running information, task attribute information, and executable binary file from the program to be injected, encapsulating them according to the format, and generating an injection data packet file; the injection data packet file is uploaded to the on-board software storage area of the spacecraft through the data transmission system; After the spacecraft receives the instruction to parse the injection program uploaded from the ground, the on-board processing module of the injection data packet parses the injection data packet file in the idle task according to the protocol format without affecting the normal execution of the system task. After the parsing is completed, a new task is added to the scheduling table or an original task is replaced.

2. The task online update system under the condition of limited memory of a spacecraft real-time system according to claim 1, characterized in that The implementation method of the ground maintenance module for system symbol information is as follows: (1) Extract the global variables and non-static function symbol address information from the executable file in the original state of the spacecraft to form an initial ground system symbol address mapping table, and form an available memory table in combination with the system memory allocation requirements; (2) When there is a program injection requirement, execute step (3); (3) Compile and link the source code of the program to be injected to generate an executable file of the program to be injected, and check whether it conflicts with the on-board software memory allocation of the spacecraft according to the distribution of the text segment and data segment of the executable file. If there is no conflict, enter step (4); if there is a conflict, enter step (5); (4) The ground generation module for injection data packets generates an injection data packet file according to the executable file, updates the ground system symbol address mapping table and the available memory table, and ends; (5) Adjust the compilation addresses of the text segment and data segment of the program to be injected, recompile to generate an injection program, and then execute step (3).

3. The task online update system under the condition of limited memory of a spacecraft real-time system according to claim 2, characterized in that The method for generating the executable file of the program to be injected is as follows: The compiler compiles the source code of the program to be injected in the original cross-compilation environment to generate an object file with relocation information. If there are multiple generated object files, they need to be combined into one object file; When the program to be injected calls the functions and variables of the original on-board system, undefined function and variable symbol information will be formed in the compiled object file; The injection program compiler searches and extracts the undefined function and variable symbol information in the original system symbol table and writes it into the link parameter file; The linker in the cross-compilation environment receives the compilation and link address parameters of the text segment and data segment specified by the user, and links the object file with the link parameter file to generate the executable file of the program to be injected.

4. The task online update system under the condition of limited memory of a spacecraft real-time system according to claim 3, characterized in that, When the object file is linked with the link parameter file, the binding of undefined function and variable symbols and addresses is realized.

5. The task online update system under the condition of limited memory of a spacecraft real-time system according to claim 1, characterized in that In the injection data packet format, the header information includes the flag of the program to be injected, the protocol version, the length, and the checksum; the program running information includes the start address and size of the text segment, the start address and size of the data segment, the start address and size of the bss segment, and the number of tasks; the task attribute information includes the task flag, the priority, the stack size, the task type, and the scheduling start point information; the executable binary file includes the content of the text segment and the content of the data segment.

6. The task online update system under the condition of limited memory of a spacecraft real-time system according to claim 1, characterized in that, The on-ground generation module of the injection data packet includes an injection program extractor, a task running attribute reader, and an injection data packet packing unit; The injection program extractor is responsible for extracting the start address and size of the text segment, the start address and size of the data segment, the start address and size of the bss segment, and the executable binary file including the content of the text segment and the content of the data segment from the executable file of the program to be injected that has been compiled. The task running attribute reader is responsible for providing the task attribute information, the number of tasks, and the settings of the header information required during the running of the program to be injected to the injection program generator and obtaining the set information, and generating the running information of the program to be injected according to the number of tasks, the start address and size of the text segment, the start address and size of the data segment, and the start address and size of the bss segment extracted by the injection program extractor. The injection data packet packing unit is responsible for packing the header information, the executable binary file of the program to be injected, the task attribute information, and the running information of the program to be injected into an injection data packet file that meets the injection format.

7. The task online update system under the condition of limited memory of a spacecraft real-time system according to claim 1, characterized in that, The implementation method of the on-board processing module of the injection data packet is as follows: (1) In the idle task, judge whether the parsed injection program instruction injected from the ground is valid. If it is invalid, exit and continue to execute other operations of the idle task. Otherwise, execute step (2); (2) Check the injection data packet file according to the protocol format. If the check fails, exit and continue to execute other operations of the idle task. Otherwise, execute step (3); (3) Extract the number of tasks and the program running address information from the injection data packet file, move them to the specified address, complete the initialization of the text segment, data segment, and bss segment, and establish the running environment of the injection program; (4) Judge whether all tasks have completed attribute parsing. If so, exit; if not, judge whether the current task name is the same as the replacement name. If the names are the same, enter step (5) to create a new task; Otherwise, enter step (6) to replace the original task; (5) Create a task according to the stack size and task ID assigned to the task. After the creation is completed, the new task is added to the task queue, the scheduling time sequence table is updated, and then return to (4) to continue executing the next task attribute parsing; (6) Find the ID of the task to be replaced, change its entry function address, and then return to (4) to continue executing the next task attribute parsing.

8. The task online update system under the condition of limited memory of a spacecraft real-time system according to claim 1, characterized in that The on-board processing module of the injection data packet completes the update of the scheduling table in the control cycle interrupt handler, so that the system performs task scheduling and running according to the new time sequence.

9. A method for online updating of tasks under memory-constrained conditions in a spacecraft real-time system, characterized in that, Including: The ground maintenance module for system symbol information checks whether the program to be injected conflicts with the on-board software memory allocation of the spacecraft, and outputs the executable file obtained after compiling and linking the program to be injected that has been checked and found to have no conflicts to the ground generation module for injection data packets; The ground generation module for injection data packets extracts program running information and executable binary files from the program to be injected, and encapsulates them in the format of injection data packets in combination with the header information and mission attribute information filled in on the ground to generate an injection data packet file; The injection data packet file is uploaded to the spacecraft through the data transmission system; The ground sends an instruction to parse the injection program to the on-board software of the spacecraft; After the spacecraft receives the instruction to parse the injection program uploaded from the ground, the on-board processing module of the injection data packet parses the injection data packet file in the idle task according to the protocol format without affecting the normal execution of the system tasks. After the parsing is completed, a new task will be added to the scheduling table or an existing task will be replaced.

10. A method for online updating of tasks under the condition of memory limitation in a spacecraft real-time system according to claim 9, characterized in that, In the injection data packet format, the injection program header information includes the injection program flag, protocol version, length, and checksum; the program running information includes the start address and size of the text segment, start address and size of the data segment, start address and size of the bss segment, and the number of tasks; the mission attribute information includes the mission flag, priority, stack size, mission type, and scheduling start point information; the executable binary file includes the content of the text segment and the content of the data segment.

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