US 2007/0186070 A1 · Computer operating system with selective restriction of memory write operations

Abstract

A computer system and method that are useful for embedded operating systems, thin client computing applications and the like, protects memory blocks in a nonvolatile version of the system program used at startup (reboot), for example in flash memory. Write operations to protected memory blocks are intercepted. A potentially revised version of any attempted re-written block is maintained in RAM and can be revised further during runtime, the original protected block remaining unwritten. A restriction process flags when or whether a revised block in the RAM is to become permanent. During a write operation or at orderly system shutdown, the revised blocks that were marked are written over the protected blocks in the nonvolatile version. The process can be embodied using file and directory attributes in variably sized Ramdisk virtual drive in a Windows XP-embedded system, providing processes with read access to the original protected block as well as the revisions, enabling configuration changes and software installations without multiple reboots.

Claims21

Dependent claims

A computer system comprising:

a programmed processor coupled read and write to a protected memory and to a random access memory, wherein the processor is programmed to intercept write operations directed to the protected memory and to maintain in the random access memory a plurality of identified memory blocks containing information that would have been written to the protected memory during said write operations but for interception thereof;
a memory management process operable to store at least one attribute flag for each of said plurality of identified memory blocks, wherein the flag marks each of said identified memory blocks as committed to become permanent in the protected memory or as not committed to become permanent;
a memory write process wherein the processor selectively writes to the protected memory or refrain from writing to the protected memory those of said identified memory blocks that are respectively marked by said flag as committed to become permanent or as not to become permanent.

A method for managing a protected memory in a computer system having a programmed processor coupled read and write to a protected memory and to a random access memory, comprising the steps of:

when a write operation is attempted to an identified block in the protected memory by a runtime process, writing to a block in the random access memory an output of the write operation while keeping on the protected memory an unchanged copy of an affected protected memory block that would have been overwritten by the write operation;
when either of a read operation and a write operation subsequently is attempted by a further runtime process for the identified block, using the block in the random access memory therefor, continuing to keep the unchanged copy on the protected memory;
operating a restriction manager process to record, for each said identified block, whether or not the identified block is committed to become a permanent change to the protected memory;
selectively writing to the protected memory at least one of said identified blocks that was committed to become permanent, and bypassing writing of at least one of said identified blocks that was not committed to become permanent.

1 more element

Dependencies are inferred from the claim text.

Computer operating system with selective restriction of memory write operations

Life of this patent

Computer operating system with selective restriction of memory write operations

Life of this patent

Abstract

Claims21