International Business Machines Corporation

Chakravarthy Jagannadhan

Grama Kasturi Harish

James Darrell Heath

Vishwanath Venkataramappa

Prabhakar Goyal

Deepak Anantarao Kulkarni

Lee Emison Hagy

A method and means for enhancing an embedded system includes a technique for generating shared library information which is stored in the ROM, the shared library information including pointers to structures for each shared library to be preloaded into the ROM, maintaining each module per library as a linked list. When the ROM image is generated, the tool writes the structures describing the preloaded libraries into the ROM image. As pointers to the structures are not valid in the ROM image, the pointers to these modules are relocated so that they are valid in the loader's address space when remapped into the loader by the kernel. At system start-up or &ldquo;boot,&rdquo; the kernel starts the embedded loader and maps the structures exactly where the loader expects to find them. Thus, when the loader attempts to load an external dynamically linked ELF executable file that is linked to one of the shared libraries in the ROM, the loader resolves all references to the preloaded library by traversing the structures provided that were mapped into its address space by the system kernel.

Method and system for loading libraries into embedded systems

A system and method for compressing portions of the operating system in a ROM image and for executing the system from the compressed image. Compression is used to reduce the size of the ROM image to reduce component cost. Low use segments are compressed. The operating system is initialized into a virtual address space with entries only for the uncompressed segments. Attempts to execute a compressed segment result in a page fault. The page fault handler determines that the segment is compressed, allocates a new page and decompresses the page into RAM for execution. The RAM copy of the segment is used for execution until the page is reused for another purpose. Later execution causes a new page fault and reallocation. A memory object reference is created for components of the image; a virtual memory page reference is then made for each component not in a compressed form; instructions are then executed by reference to the image; a page fault is detected when attempting to execute an instruction in a component not having a page table reference; a compressed image is then decompressed into the random access memory in response to the page fault.

Computer system and method for selectively decompressing operating

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Chakravarthy Jagannadhan