Dynamically configurable kernel

• US 5,634,058 A
• Filed: 10/11/1995
• Issued: 05/27/1997
• Est. Priority Date: 06/03/1992
• Status: Expired due to Term

• Current Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Original Assignee: Sun Microsystems Incorporated (Oracle Corporation)
• Inventors: Allen, Tom, Provino, Joseph E., Pittore, William F.
• Primary Examiner(s): Kriess, Kevin A.
• Assistant Examiner(s): Toplu, Lucien
• Application Number:
  US08/540,875
• Time in Patent Office: 594 Days
• Field of Search: 395/700
• US Class Current: 717/163
• CPC Class Codes: G06F 9/44521 Dynamic linking or loading; Link editing at or after load time, e.g. Java class loading

Abstract

A dynamically configurable operating system is achieved by providing a module sub-system which intercepts requests by processes to access a module in the operating system and determines whether the module has been loaded in the kernel memory and linked the other modules located in the kernel memory and installed in the appropriate table. If the module has been into the kernel memory, and installed the module sub-system grants the requesting installed process access to the module and processing continues. If the module has not been loaded into the kernel memory, the module sub-system will retrieve a copy of the module stored and copy it into kernel memory. The module is then linked to the other modules located in the kernel and installed. Once the module is loaded and linked and installed, access is granted to the requesting process and normal processing continues.

Claims

1. A computer system comprising a central processing unit (CPU) and memory, said CPU executing in accordance with an operating system comprising modules of code, said computer system comprising a module sub-system for dynamically loading modules of the operating system into operating system memory and installing loaded modules as part of the operating system for access, said subsystem comprising:

a control module loaded into operating system memory and installed as part of the operating system, said control module intercepting a request for access to a module such that the request is not performed, said control module further determining whether the requested module has been loaded and installed;

a loader module loaded into operating system memory and installed as part of the operating system, said loader module coupled to the control module for copying compiled module code for the requested module into the operating system memory to provide a loaded module;

a linker module loaded into operating system memory and installed as part of the operating system, said linker module coupled to the control module for resolving the references between the loaded module and at least one module previously loaded in the operating system memory and installed;

an install module loaded into operating system memory and installed as part of the operating system, said install module coupled to the control module for providing references to the loaded module thereby indicating that the loaded module is a loaded and installed module;

if said control module determines that the requested module has not been loaded and installed, said control module controlling the loader module, linker module and install module respectively to load, link and install the requested module, said control module further permitting the request for access to execute once the requested module has been loaded and installed; and

if said control module determines that the requested module has been loaded and installed, said control module immediately permitting the request for access to execute.

2. The computer system as set forth in claim 1, wherein the operating system further comprises at least one module configuration table comprising information regarding modules, said control module reading the module configuration table to determine whether the requested module has been loaded into the operating system memory and installed.

3. The computer system as set forth in claim 2, wherein each requested module comprises a wrapper to provide information indicating whether the module is a loadable file, a type of module, and a pointer to installation code located in the operating system for the type of module, said installation code providing specific instructions as to the installation of the module information in the configuration table.

4. The computer system as set forth in claim 1, wherein said module configuration table comprises a record for each module, each record comprising at least one entry having a value indicating that the module is loaded in the operating system memory and installed.

5. The computer system as set forth in claim 1, wherein said loader module determines the size of a file of compiled module code, allocates operating system memory for placement of the file and writes the file in the memory allocated.

6. The computer system as set forth in claim 5, wherein if the loader module determines that insufficient operating system memory exists to write the file, a module is unloaded from the operating system to provide sufficient operating system memory.

7. The computer system as set forth in claim 4, wherein the control module determines if the requested module is loaded and installed by determining if the predetermined entry in the record contains a value indicative that the module is loaded into the operating system and installed.

8. The computer system as set forth in claim 4, wherein said install module allocates a record in said module configuration table for the requested module when the requested module is first loaded into the operation system memory and installed.

9. The computer system as set forth in claim 4, wherein a record in the module configuration table is preallocated for each module that can be loaded and installed.

10. The computer system as set forth in claim 4, wherein the install module establishes a record in the module configuration table for the loaded module when the loaded module is first installed in the operating system, said record comprising the entry containing the value indicative that the loaded module is installed in the operating system.

11. The computer system as set forth in claim 4, wherein a plurality of modules are loaded and installed and said module subsystem further comprises:

means for selecting a loaded and installed module to unload and uninstall from the operating system;

means for nullifying the entry, that indicates that the selected module is loaded in the operating system and installed, in the module configuration table such that the entry in the module configuration table indicates that the selected module is no longer loaded or installed;

means for reallocating the operating system memory occupied by the selected loaded and installed module to unload such that the memory can be utilized to load another module into the operating system.

12. The computer system as set forth in claim 10, wherein said control means determines if the requested module is loaded and installed by determining if a record exists for the requested module in the module configuration table and if a record exists, if the entry in the record contains the value indicative that the module is loaded and installed in the system.

13. In a computer system comprising resources such as a Central Processing Unit (CPU), memory and input/output means, an operating system which executes processes and utilizes the resources, the operating system comprising at least one module loaded into operating system memory and installed as part of the operating system, a process for dynamically configuring the operating system by loading the modules into operating system memory and installing the loaded modules on an as needed basis comprising the steps of:

when a requesting process issues a request to the operating system to access a requested module;

a module subsystem intercepting the request to access the requested module such that the request is temporarily not executed by the operating system, and

determining if the requested module has been loaded and installed into the operating system by determining if a module configuration table stored in operating system memory contains an entry for the requested module having a value indicative that the requested module has been loaded into the operating system memory and installed;

if the module has not been loaded into the operating system memory and installed into the operating system, loading the module comprising the steps of;

copying compiled module code of the requested module into the operating system memory such that the requested module is a loaded module, and

resolving all references between the loaded module and the at least one loaded and installed module,

installing the loaded module by providing references to the loaded module necessary for requests for access thereby indicating that the requested module has been loaded and installed, wherein the loaded module is now accessible, and

permitting the intercepted request for access to process; and

if the module has been loaded into the operating system memory and installed into the operating system, immediately executing the request for access to execute.

14. The process for dynamically configuring an operating system as set forth in claim 13 wherein a record is allocated for a module when a modules is first loaded and installed, said step of determining further comprising the step of ascertaining whether a record for the requested module exists, wherein if a record for the requested module does not exist or if a record for the requested module exists and the entry indicates the requested module is not loaded and installed, the module is loaded and installed.

15. The process for dynamically configuring an operating system as set forth in claim 13, further comprising the steps of:

selecting a loaded and installed module to unload and uninstall from the operating system;

nullifying the entry for the selected module in the module configuration table to indicate that the selected module is uninstalled; and

reallocating the operating system memory occupied by the selected module to unload such that the memory can be utilized to load another module into the operating system.

16. The process for dynamically configuring an operating system as set forth in claim 13, further comprising the steps of:

selecting a module to unload from the operating system, said module being in an uninstalled state, as indicated by a null entry in the entry for the selected module in the module configuration table; and

reallocating the operating system memory occupied by the selected module to unload such that the memory can be utilized to load another module into the operating system.

17. The process for dynamically configuring an operating system as set for in the claim 16 wherein said process further comprises the step of uninstalling at least one installed and loaded module according to predetermined parameters by nullifying the entry for the installed and loaded module in the module configuration table.

18. In a computer system comprising resources such as a Central Processing Unit (CPU), memory and input/output means, an operating system comprising a kernel memory comprising a plurality of installed and loaded modules which execute processes and utilize the resources, a process for loading modules into the kernel memory on an as needed basis comprising computer implemented steps of:

compiling each module into an object code format;

storing the compiled files representative of the modules in a memory external to the kernel memory;

providing at least one module configuration table in the kernel memory identifying modules loaded into the kernel memory and installed into the kernel as part of the operating system;

when a requesting process issues an access request for a requested module, said process for loading,

intercepting the access request to the module configuration table;

reviewing the entries in the module configuration table to determine if the requested module has been loaded and installed into the kernel,

if the module configuration table indicates that the module has not been loaded and installed into the kernel,

reading the compiled file representative of the module,

determining the size of the file,

allocating space in the kernel memory for the file,

copying the file into kernel memory,

resolving all references between the requested module and the loaded and installed modules,

installing the module by identifying the location of the loaded module and updating the module configuration table to indicate that the module has been loaded and installed into the kernel, and

permitting the request to access to execute; and

if the module configuration table indicates that the module has been loaded and installed into the kernel, immediately permitting the request to access to execute.