Identification of Uncommitted Memory Blocks During an Initialization Procedure

• US 20080065852A1
• Filed: 09/08/2006
• Published: 03/13/2008
• Est. Priority Date: 09/08/2006
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Moore, Derick Guy, Rawe, Lawrence, Wade, Roy
• Granted Patent: US 7,475,215 B2
• Time in Patent Office: Days
• US Class Current: 711/170
• CPC Class Codes: G06F 12/0223 User address space allocation, e.g. contiguous or non contiguous base addressing
• CPC Class Codes: G06F 12/023 Free address space management
• CPC Class Codes: G06F 13/4068 Electrical coupling
• CPC Class Codes: G06F 9/4411 Configuring for operating with peripheral devices; Loading of device drivers

Abstract

An apparatus and method are described for identifying uncommitted memory in a system RAM during an initialization process of a computer system, such as a boot procedure or power-on self test, during which memory management is uncontrolled. In various embodiments of the invention, repeating patterns that are indicative of uncommitted memory blocks are identified within a conventional memory area of the system RAM. At least some of the uncommitted memory blocks are allocated for use by an option ROM or other BIOS data and a table is created identifying these uncommitted memory blocks. After the BIOS code exits the system RAM, the table is used to restore the uncommitted memory blocks into their previous data states.

Claims

1. An uncommitted memory identifier apparatus for identify uncommitted memory blocks in a memory device during an initialization procedure, the apparatus comprising:

a test pattern identifier, coupled to read a first memory block within a system SRAM, that identifies a test pattern in the first memory block;

a comparator, coupled to the test pattern identifier and coupled to read a second memory block contiguous to the first memory block, that compares the test pattern to a second pattern read from the second memory block to identify if the test pattern is repeating; and

an uncommitted memory boundary identifier, coupled to the comparator, that defines start and end boundaries of an uncommitted memory space based on the comparison of the test pattern to the second pattern and at least one user-defined limit applied to the analysis of the system SRAM.

2. The uncommitted memory identifier apparatus of claim 1 further comprising a table of patterns and uncommitted memory that records the test pattern and location of the first memory block, the second pattern and the location of the second memory block, and the location of the uncommitted memory space.

3. The uncommitted memory identifier apparatus of claim 2 wherein data stored within table of patterns and uncommitted memory is used to restore the uncommitted memory space to its previous data state after a set of BIOS code has been stored and executed during an initialization procedure.

4. The uncommitted memory identifier apparatus of claim 1 wherein the comparator compares the test pattern to a third pattern read from a third memory block, that is contiguous to the second memory block, to identify if the test pattern continues to repeat.

5. The uncommitted memory identifier apparatus of claim 1 wherein the test pattern and second pattern are located within a conventional memory area within the system SRAM.

6. The uncommitted memory identifier apparatus of claim 5 wherein the conventional memory area is identified by a stack pointer in the system SRAM and is set prior to reading the test pattern.

7. The uncommitted memory identifier apparatus of claim 1 wherein the length of the test pattern and second pattern is a dword.

8. The uncommitted memory identifier apparatus of claim 1 wherein the length of the test pattern and second pattern is a qword.

9. The uncommitted memory identifier apparatus of claim 1 wherein BIOS code is stored within the identified uncommitted memory space and executed according to control software.

10. A method for identifying uncommitted memory space within a memory device, the method comprising:

defining a set of criteria applied to an analysis of the memory device that establishes at least one parameter from which uncommitted memory space may be identified;

reading a test pattern from a first memory block within the memory device;

reading a second pattern from a second memory block that is contiguous to the first memory block;

comparing the test pattern to the second pattern to determine whether the test pattern and second pattern are the same; and

identifying a combination of the first and second memory blocks as uncommitted memory space if the test pattern and the second pattern are the same and the size of the combination is above threshold value.

11. The method of claim 11 further comprising the steps of:

reading a third pattern from a third memory block that is contiguous to the second memory block if the test pattern and the second pattern are the same;

comparing the test pattern to the third pattern to determine whether the test pattern and the third pattern are the same; and

wherein the uncommitted memory space is a combination of the first, second and third memory blocks if the test pattern and the third pattern are the same.

12. The method of claim 11 wherein the first and second memory blocks are located within a conventional memory area of the memory device.

13. The method of claim 11 further comprising the step of creating a table that stores the address of the first memory block and test pattern, the address of the second memory block and second pattern, and the location of the uncommitted memory space.

14. The method of claim 13 wherein the table is used to restore the uncommitted memory space to its previous data state after a set of BIOS code has been stored and executed during an initialization procedure.

15. The method of claim 11 wherein the length of the first memory block and the second memory block is a dword.

16. The method of claim 11 wherein the length of the first memory block and the second memory block is a qword.

17. The method of claim 11 wherein the identification of the test pattern and comparison of the test pattern to the second pattern is performed throughout an entire conventional memory area within the memory device.

18. A computer program product embodied on a computer readable medium for identifying uncommitted memory space within a memory device, the computer program product comprising computer instructions for:

defining a set of criteria applied to an analysis of the memory device that establishes at least one parameter from which uncommitted memory space may be identified;

reading a test pattern from a first memory block within the memory device;

reading a second pattern from a second memory block that is contiguous to the first memory block;

comparing the test pattern to the second pattern to determine whether the test pattern and second pattern are the same; and

identifying a combination of the first and second memory blocks as uncommitted memory space if the test pattern and the second pattern are the same and the size of the combination is above threshold value.

19. The computer program product of claim 18 further comprising computer instructions for:

reading a third pattern from a third memory block that is contiguous to the second memory block if the test pattern and the second pattern are the same;

comparing the test pattern to the third pattern to determine whether the test pattern and the third pattern are the same; and

wherein the uncommitted memory space is a combination of the first, second and third memory blocks if the test pattern and the third pattern are the same.

20. The computer program product of claim 18 further comprising computer instructions for creating a table that stores the address of the first memory block and test pattern, the address of the second memory block and second pattern, and the location of the uncommitted memory space.

21. The computer program product of claim 20 wherein the table is used to restore the uncommitted memory space to its previous data state after a set of BIOS code has been stored and executed during an initialization procedure.

22. The computer program product of claim 18 wherein the identification of the test pattern and comparison of the test pattern to the second pattern is performed throughout an entire conventional memory area within the memory device.