JP4735765B2 - Linux program startup system - Google Patents

Description

The present invention is suitable for use in an embedded device in which a Linux program (hereinafter also simply referred to as Linux) is mounted (embedded) as an operating system.
The present invention relates to an inux program starting system.

Various devices such as home appliances, wristwatches, small terminals such as mobile phones and PDSs, Internet-related devices, and other devices that operate with various computer application programs (hereinafter also simply referred to as applications) have operating systems (hereinafter also referred to as OSs). )
Many of them are equipped with basic software. In recent years, Linux as an open source has attracted attention as an OS for mounting (embedding) devices.

As a feature of this Linux, only the core part of the OS called the kernel (Linux kernel) is devoted to development, and other parts can be easily obtained from free software released royalty-free. A point is mentioned.

This Linux is constructed on the premise of logical access to a block device using a file system. In other words, in Linux, when a kernel is started, a basic part called a root file system is mounted from a device {a device (storage area) in which a file system is stored is made a device that can be recognized (accessed) from the boot kernel, and the device Means that the boot kernel can access various files including applications in the stored file system}
Various applications can be used to access data stored in the block device.

Usually, a personal computer (hereinafter, referred to as a standard system on which Linux operates)
For example, in an IBM / AT compatible machine, which is a personal computer), information indicating a device mounted at the time of booting (booting) is set as a default in a hard disk (HDD) boot area called MBR (Master Boot Record) in advance. Has been written. If you want to boot a file system using a device different from the default, it is common practice to select the device with the file system you want to boot using the command line or menu format. .

In Linux, the root file system is mounted by an argument passed to the kernel. However, in embedded devices, in device
There is a case where a file system mounted on a RAM disk called itrd is used as an initial root file system, and a root file system that is originally mounted from the initrd is mounted from the mounted device.

By the way, for example, in a personal computer, when updating a program (installed) in the personal computer, for example, a Linux program, only the execution file is exchanged,
Further, in the case of a user who has knowledge of Linux, an environment for executing a new Linux program can be built in the personal computer by adding a new function program after rebuilding the kernel.

In this regard, in the Linux embedded device, from the viewpoint of maintainability, it is efficient to rewrite the kernel and the file system linked to this kernel (hereinafter also referred to as userland) to renew the execution environment of the Linux program. It is considered to be.

In addition, for example, in a personal computer, there are a plurality of devices such as HDDs and CD-ROMs that can store a boot program, and a program including a boot loader is updated from a certain device and the device fails. However, it is possible to restore the personal computer relatively easily by starting a program including a boot loader installed in another device.

However, in an embedded device, it is necessary for the user to select a device on which a file system to be booted is installed, so that the user is confused, and a mechanism for automatically booting the file system is required. In addition, since embedded devices are often turned on and off frequently by users from the outside, rewriting of the boot loader itself increases the risk of being unable to boot, so a technical background of using another device identification method There is also.

In this regard, the same or different version of the program {kernel and linked file system (userland)} is redundantly recorded in two memory areas (memory banks) 2
A bank system is also known, and it is possible to switch the effective puncture depending on whether or not the program operates normally, and the above-described risk of inability to boot can be reduced.

In this two-bank system, when a defect is corrected or a function is added by updating the program on an embedded device, the update operation must be completed only when the update of one program is completed and the updated program operates normally. The program is supposed to be disabled.

Therefore, even if the update of the program recorded in one bank fails, it is possible to continue to hold the currently operating program recorded in the other bank.

As the above-described two-bank system, there is one disclosed in Patent Document 1. The firmware storage device of the computer system disclosed in Patent Document 1 is a firmware storage device that redundantly stores the same or different versions of firmware in two memory banks.

According to this firmware storage device, while one of the two memory banks is selected, the other memory bank is write-protected. Then, one of the two memory banks is selected, the validity of the firmware stored in the memory bank not selected is checked, and the version of the firmware stored in the selected memory bank is changed to the memory bank not selected. Is compared with the version of the firmware stored in, and the comparison result is generated. According to the comparison result, one of the firmware stored in the two memory banks is selected, the computer system is started up using the firmware stored in the selected memory bank, and the firmware is stored within a predetermined time. Select this unselected memory bank if your computer system is not ready for normal operation,
Then reset the processor.

With such a configuration, it is possible to efficiently ensure the integrity of the system firmware and easily change the firmware. It is also possible to change the firmware of such a system while ensuring that the firmware is sufficient to keep the computer system operational. Furthermore, automatic selection from a plurality of firmware banks in the computer system can be performed.

Specifically, as disclosed in the paragraph number of Patent Document 1, two memory banks 502 are used.
And 504 are managed by the controller 505, which reads firmware from the memory banks 502 and 504, and the memory bank 502
And firmware writing from 504 and 504, respectively.

Japanese Patent No. 3033642

However, in a Linux program embedded device using Linux as an OS, if there are multiple areas (banks) for storing Linux programs (two or more banks), the activated kernel is stored in each of the multiple banks. In addition, it is difficult to determine which user land of a plurality of user lands should be mounted as a user land linked to the boot kernel.

The present invention has been made in view of the above-described circumstances, and makes it possible to identify an effective file system linked to a boot kernel from a plurality of file systems recorded in a plurality of banks in starting a Linux program. It is an object of the present invention to provide a Linux program starting system.

In order to solve the above problems, the invention according to claim 1
A Linux program starting system for starting a kernel and mounting a user land in a Linux program comprising a kernel and a user land operating in a pair with the kernel,
A first area for storing a kernel of the first Linux program, a second area for storing a user land of the first Linux program linked to the kernel, and an old and a new of the first Linux program are identified. A first bank having the first to third areas with a third area for storing first identification information for the first, a fourth area for storing a kernel of the second Linux program, and the kernel A fifth area for storing a userland of the second Linux program linked to the second Linux program, and a sixth area for storing second identification information for identifying the old and new of the second Linux program. A first memory comprising a second bank having four to sixth areas, and a seventh area for storing a boot loader;
A predetermined area for storing bank identification information indicating a bank selected from the first bank and the second bank according to the first and second identification information by the activated boot loader. A second memory,
The boot loader is read out from the seventh area and activated, and the activated boot loader selects an effective bank from the first and second banks according to the comparison result of the read out first and second identification information. One is selected, the bank identification information indicating the selected bank is written to the predetermined area of the second memory, the kernel is read and activated from the selected bank, and the activated kernel A control unit for specifying a bank in the first memory in which the kernel is activated by the bank identification information read from the second memory, and mounting a user land stored in the specified bank;
A Linux program start system characterized by comprising:
I will provide a.
In order to solve the above problems, the invention according to claim 2
A Linux program starting system for starting a kernel and mounting a user land in a Linux program comprising a kernel and a user land operating in a pair with the kernel,
An area for storing a kernel of one Linux program, an area for storing a userland of the one Linux program linked to the kernel, and an area for storing identification information for identifying the old and new of the one Linux program A first memory comprising a plurality of banks each having the three areas, and an area for storing a boot loader,
A second memory having a predetermined area for storing bank identification information indicating a bank selected from the plurality of banks according to each identification information by the activated boot loader;
The boot loader is read from the first memory and activated, and the activated boot loader is used to select one valid bank from the plurality of banks according to the comparison result of the read identification information. The bank identification information indicating a bank is written in the predetermined area of the second memory, a kernel is read from the selected bank and activated, and the kernel that has been activated reads the second memory from the second memory. A control unit that identifies a bank in the first memory in which the kernel is activated by bank identification information, and mounts a user land stored in the identified bank;
A Linux program start system characterized by comprising:
I will provide a.

  According to the present invention, the file system by the boot kernel read from the bank selected as valid by writing the bank identification information indicating the bank selected as the valid bank into the second memory by the boot loader activated. At the time of determination, the file system corresponding to the boot kernel can be easily identified based on the bank identification information written in the second memory.

The schematic block diagram which shows schematic structure of the motherboard containing the Linux program starting system mounted in the embedded apparatus concerning embodiment of this invention. It is a figure which shows roughly the memory map of the flash memory which stores the Linux program in the Linux program starting system which concerns on embodiment of this invention. (A) is a figure which shows roughly the memory map of the main memory concerning embodiment of this invention, (b) expands a part of kernel non-recognition memory area | region in Fig.3 (a). FIG. It is a schematic flowchart which shows an example of the starting process of the Linux program starting system which concerns on embodiment of this invention.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

With reference to FIG. 1, a schematic configuration of a mother board 11 including a Linux program starting system 1 according to the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described. The mother boat 11 is preinstalled in application operating devices such as home appliances, wristwatches, small terminals such as mobile phones and PDSs, and Internet-related devices.

As shown in FIG. 1, the motherboard 11 is provided with a host bus 13 including an address bus and a data bus connected via a CPU / PCI bridge 31, and a standardized PCI bus 15 having a 32-bit width. ing.

Connected to the host bus 13 are a CPU 17 having an internal cache memory Cm and a data bus of a predetermined bit, an external cache memory 21 made of SRAM, and a cache controller 19 for controlling reading / writing of data to / from the external cache memory 21. ing. The host bus 13 is connected to a main memory 25 composed of DRAM and a DRAM controller 23 for controlling reading / writing and refreshing of data to / from the main memory 25.

Further, a flash memory 29 as an example of a rewritable recording medium made of, for example, a NAND memory, a flash memory controller 27 that controls reading / writing of data to / from the flash memory 29, and a CPU are connected to the host bus 13. A CPU / PCI bridge 31 and the like for connecting the host bus 13 and the PCI bus 15 are connected to each other.

On the other hand, a LAN card for controlling a LAN protocol, for example, is connected to the PCI bus 15 via a PCI expansion slot 33.

The flash memory controller 27 controls reading / writing of data from / to the flash memory 29 according to a block transfer command related to reading / writing of data given from the CPU 17.

The flash memory 29 is composed of a so-called NAND memory, and is configured to read and write data stored in blocks of, for example, 2 kbytes as one unit. In the embodiment, two) Linux programs L1 and L2 are stored.

In this embodiment, one Linux program in the plurality of Linux programs L1 and L2 is updated (upgraded) to a new program.

Next, the specific contents of the Linux programs L1 and L2 stored in the flash memory 29 will be described for each storage area with reference to FIG.

As shown in FIG. 2, the boot loader area 101 (addresses # 1 to # 1) of the flash memory 29
In the area up to # 2, a boot loader for booting the Linux program is stored. The boot loader area 101 is, for example, MIP when the entire system 1 is reset.
This is the area designated by the S architecture program counter, and the system 1 (
CPU 17) The boot loader is first transferred to the main memory 25 at startup.

Header information including version information (information for identifying the new and old) of the kernel A of the Linux program L1 is stored in an area (first header bank area) from addresses # 2 to # 3 of the flash memory 29. Yes.

Kernel A area 102 of flash memory 29 (area from address # 3 to # 4: first
Kernel bank area) stores the kernel A of the Linux program L1, and this kernel A is transferred to the main memory 25 by the processing of the CPU 17 in accordance with the boot loader transferred to the main memory 25. The kernel A contains a file system recognition (mounting) program called initrd when the kernel is created. The processing of the CPU 17 is performed by the cache controller 19 and the DRA as necessary.
Although the process of M controller 23 is also included, it demonstrates as a process of CPU only.

The header information of the kernel B of the Linux program L2 is stored in an area from the addresses # 4 to # 5 (second header bank area) of the flash memory 29.

Kernel B area 103 of flash memory 29 (area from address # 5 to # 6: second
Kernel bank area) stores the kernel B of the Linux program L2, and this kernel B is transferred to the main memory 25 by the processing of the CPU 17 according to the boot loader transferred to the main memory 25. The kernel B also includes a file system recognition (mounting) program called initrd when the kernel is created.

Userland A area 104 of flash memory 29 (area from address # 6 to # 7:
In the first user bank area, a user land A that is a file system linked to the kernel A of the Linux program L1 is stored. This user land A is not transferred to the main memory 25 by kernel processing (processing of the CPU 17 according to the kernel), but is mounted or unmounted by kernel processing.

Userland B area 105 of flash memory 29 (area from address # 7 to # 8:
The second user bank area) stores a user land B that is a file system linked to the kernel B of the Linux program L2. This user land B is not transferred to the main memory 25 by kernel processing (processing of the CPU 17 in accordance with the kernel), but is mounted or unmounted by kernel processing.

In the present embodiment, the first Linux program L1 (kernel A, userland A
) (First header bank area, first kernel bank area, first user bank area) are collectively referred to as bank A, and the second Linux program L2 (kernel B, user land) The area (B header area, second kernel bank area, second user bank area) in which B) is stored is generically referred to as bank B.

In the data area (address # 8 to # 9) of the flash memory 29, the activated Linux
Various data that can be used by the program L1 or L2 are stored.

On the other hand, FIG. 3 is a diagram showing a recording area (memory area) of the main memory 25 according to the present embodiment.

As shown in FIG. 3, the fixed area 25a1 of the main memory 25 is determined when the kernel is created as a memory area recognized by the boot kernel. On the other hand, since the non-recognized area 25a2 that is not recognized by the boot kernel is not under the control of the boot kernel, it is assumed to be used for a special purpose.

In the present embodiment, this kernel non-recognized memory area 25a2 is made empty so that boot information including valid bank identification information at the time of kernel expansion on the main memory 29 by the boot loader can be written. In addition, after booting Linux, a memory area that is not used until an application operates can be used to write boot information.

Next, L of the CPU 17 in the Linux program starting system 1 according to the present embodiment.
The inux program activation process will be described with reference to FIG.

When the Linux program is activated, the boot loader stored in the data area (address # 1 to address # 2) of the flash memory 29 is loaded into the main memory 25 and activated. The activated boot loader (that is, the CPU 17 according to the boot loader) reads the header information including the kernel A version information stored in the data area (address # 2 to address # 3) of the flash memory 29 and the data area of the flash memory 29. (Address #
4 to read the header information including the version information of the kernel B stored in the address # 5).

Subsequently, as shown in FIG. 4, the boot loader compares the header information of the read kernel A and kernel B and determines, for example, a bank in which a new version of the kernel is stored as a valid bank in step S301. (Step S301). That is, when the Linux program L1 is newly updated, the version information of the kernel A is information indicating that it is newer than the version information of the kernel B.
When the bank A is determined as a valid bank and the Linux program L2 is newly updated, the version information of the kernel B is information indicating that it is newer than the version information of the kernel A. It is determined as a valid bank.

Next, in step S302, the boot loader stores identification information (identification information representing bank A if bank A is valid, and identification information representing bank B if bank B is valid) for identifying the valid bank. Is written (described) in, for example, the kernel non-recognized memory area 25a2.

Next, in step S303, the boot loader loads and expands a valid kernel (one of the kernels A and B) into the main memory 25, starts the kernel, and starts the startup kernel (kernel). Shift control to code).

Subsequently, in step S304, the boot kernel (that is, C according to the boot kernel).
The PU 17) activates a script for loading various drivers in the initial root file system (initrd) in the activation kernel.

Next, in step S305, the boot kernel is a memory area in which the boot kernel can recognize the kernel non-recognized memory area 25a2 of the main memory 25 using, for example, a pointer from the kernel recognition area 25a1 in the initrd boot script. Mapping (mmap) into the virtual memory space of the boot kernel space, reading the bank information written in the mapped area, and determining from which bank the own kernel was booted.

In this determination, when the read bank information is bank A, it is determined that the own kernel is started from bank A (determination in step S306 → YES), and the startup kernel is
The process proceeds to step S307.

In this step S307, the boot kernel mounts the user land A stored in the bank A as a root file system, that is, connects the user land A to the root directory (/) of the boot kernel (kernel A) to create a hierarchy. By setting the file system, the file system can be recognized (accessed) from the boot kernel.

On the other hand, when the read bank information is bank B, it is determined that the own kernel is started from bank B (determination in step S306 → NO, determination in step S308 → YES).
The boot kernel proceeds to step S309.

In step S309, the boot kernel mounts the user land B stored in the bank B as a root file system.

In step S308, if any bank A and B cannot be determined to be valid, the Linux program activation process is terminated as an error has occurred.

When the mounting of the user land linked to the boot kernel is completed in this way, the boot kernel continues normal boot processing according to the setting.

As described above, according to the present embodiment, a plurality of Linux programs L1 and L2
Are stored in a plurality of banks of the flash memory 29, the user land linked to the boot kernel can be automatically identified and mounted as a root file system.

As a result, even when the Linux program recorded in one bank is updated using the 2-bank method in the Linux program embedded device, the root file system (user land) linked with the updated boot kernel cannot be recognized. Thus, the reliability of the startup process of the Linux program can be improved.

In the present embodiment, the flash memory is used as a recording medium for storing the Linux program, but another rewritable recording medium may be used.

Moreover, although the structure shown in FIG. 1 was shown as a motherboard mounted in an embedded device, this invention is not limited to this structure, The computer hardware structure which can implement | achieve the content demonstrated in FIGS. If it is.

Furthermore, in this embodiment, the redundant configuration of the Linux program recorded in the flash memory is a two-bank configuration in which two Linux programs are stored in each of the two banks of the flash memory. However, the present invention is limited to this configuration. Instead of this, a redundant configuration may be adopted in which three or more Linux programs are stored in each of three or more banks of the flash memory.

In this embodiment, the new version of the Linux program is activated as a valid program. However, the present invention is not limited to this, and the old version of the Linux program is activated as an effective program. You may comprise as follows.

11 Motherboard 13 Host bus 15 PCI bus 17 CPU
21 External cache memory 25 Main memory 27 Flash memory controller 29 Flash memory 31 CPU / PCI bridge 33 PCI expansion slot 35 LAN card # 1 to # 2 Boot loader storage area # 2 to # 3 First header bank area # 3 to # 4 First kernel bank area # 4 to # 5 Second header bank area # 5 to # 6 Second kernel bank area # 6 to # 7 First user bank area # 7 to # 8 Second user bank area

Claims (2)

A Linux program starting system for starting a kernel and mounting a user land in a Linux program comprising a kernel and a user land operating in a pair with the kernel,
A first area for storing a kernel of the first Linux program, a second area for storing a user land of the first Linux program linked to the kernel, and an old and a new of the first Linux program are identified. A first bank having the first to third areas with a third area for storing first identification information for the first, a fourth area for storing a kernel of the second Linux program, and the kernel A fifth area for storing a userland of the second Linux program linked to the second Linux program, and a sixth area for storing second identification information for identifying the old and new of the second Linux program. A first memory comprising a second bank having four to sixth areas, and a seventh area for storing a boot loader;
A predetermined area for storing bank identification information indicating a bank selected from the first bank and the second bank according to the first and second identification information by the activated boot loader. A second memory,
The boot loader is read out from the seventh area and activated, and the activated boot loader selects an effective bank from the first and second banks according to the comparison result of the read out first and second identification information. One is selected, the bank identification information indicating the selected bank is written to the predetermined area of the second memory, the kernel is read and activated from the selected bank, and the activated kernel A control unit for specifying a bank in the first memory in which the kernel is activated by the bank identification information read from the second memory, and mounting a user land stored in the specified bank;
A Linux program starting system characterized by comprising: A Linux program starting system for starting a kernel and mounting a user land in a Linux program comprising a kernel and a user land operating in a pair with the kernel,
An area for storing a kernel of one Linux program, an area for storing a userland of the one Linux program linked to the kernel, and an area for storing identification information for identifying the old and new of the one Linux program A first memory comprising a plurality of banks each having the three areas, and an area for storing a boot loader,
A second memory having a predetermined area for storing bank identification information indicating a bank selected from the plurality of banks according to each identification information by the activated boot loader;
The boot loader is read from the first memory and activated, and the activated boot loader is used to select one valid bank from the plurality of banks according to the comparison result of the read identification information. The bank identification information indicating a bank is written in the predetermined area of the second memory, a kernel is read from the selected bank and activated, and the kernel that has been activated reads the second memory from the second memory. A control unit that identifies a bank in the first memory in which the kernel is activated by bank identification information, and mounts a user land stored in the identified bank;
A Linux program starting system characterized by comprising:

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