US5386522A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dynamic physical address aliasing during program debugging
Assignee: International Business Machines Corp
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Filing: 1991-12-30
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Granted: 1995-01-31
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Expires: 2011-12-30
Abstract
Abstract The physical memory of a computer may not be directly accessable to the operator during the operation of a program due to the operational requirements of the operating system. Direct access to the physical memory of the computer during such operation may be possible through the aliasing of the physical memory locations and the creation of virtual alias addresses which will then give operator the necessary control to directly access any memory location thereby permitting the debugging of the program.
Inventors
- 👤 David H. Evans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:38
CPC Classifications
G; G06; G06F; G06F11/00; G06F11/36; G06F11/362; G06F12/00; G06F12/02; G06F12/08; G06F12/10
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
253 words
A method of converting a physical address of a portion of a program to be debugged, stored in a memory device of an information storage location to a linear address corresponding to said physical address, said physical address comprising a physical address frame and an offset value, said method comprising the steps of: a) providing a debugger program stored in physical memory; b) providing a program to be debugged stored in said physical memory; c) determining a permanent linear address of said debugger program; d) excerpting a portion of said permanent linear address of said debugger program to determine an index to a Page Directory Entry that maps said debugger program; e) said debugger program reading said Page Directory Entry to acquire a physical address of a Page Table which in turn maps the debugger program; f) creating a Global Descriptor Table Entry which accesses said Page Table; g) searching said Page Table for three unused Page Table Entries; h) modifying two of said three unused Page Table Entries to map any portion of said program to be debugged; i) converting said physical address of said information storage location of said program to be debugged by assembling a linear address comprising said Page Directory Entry index and an index of the first of said three Page Table Entries; and j) said debugger program accessing said information storage location using said linear address and using contents of said information storage location for display purposes or for modifying said contents of said information storage location.
Claim 2
Independent Claim
253 words
A method of converting a physical address of a portion of a program to be debugged, stored in a memory device of an information storage location to a linear address corresponding to said physical address, said physical address comprising a physical address frame and an offset value, said method comprising the steps of: a) providing a debugger program stored in physical memory; b) providing a program to be debugged stored in said physical memory; c) determining a permanent linear address of said debugger program; d) excerpting a portion of said permanent linear address of said debugger program to determine an index to a Page Directory Entry that maps said debugger program; e) said debugger program reading said Page Directory Entry to acquire a physical address of a Page Table which in turn maps the debugger program; f) creating a Global Descriptor Table Entry which accesses said Page Table; g) searching said Page Table for three unused Page Table Entries; h) modifying two of said three unused Page Table Entries to map any portion of said program to be debugged; i) converting said physical address of said information storage location of said program to be debugged by assembling a linear address comprising said Page Directory Entry index and an index of the first of said three Page Table Entries; and j) said debugger program accessing said information storage location using said linear address and using contents of said information storage location for display purposes or for modifying said contents of said information storage location.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein said three unused Page Table Entries are contiguous.
Claim 4
Dependent Claim
20 words
The method of claim 2 wherein said modifying step modifies the first two of said three unused Page Table Entries.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-01-30 | 1998-08-01 | 1999-01-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-30 | 2002-08-01 | 2003-01-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-30 | 2006-08-01 | 2007-01-31 | $7700.00 | Window Closed / Lapsed |