International Business Machines Corporation

James Darrell Heath

Grama Kasturi Harish

Vishwanath Venkataramappa

Deepak Anantarao Kulkarni

Prabhakar Goyal

Chakravarthy Jagannadhan

Lee Emison Hagy

William F Quinn

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 method and means for enhancing an embedded system includes means for and steps of executing a boot routine; activating a ROM loader routine; initializing an I/O subsystem; activating an embedded OS; creating a dynamically linked embedded system loader task, and having the embedded OS map the Global Coerced Memory (GCM) and the Global Shared Memory (GSM) into its address space so that it can access shared libraries; loading each of a plurality of executable programs, and mapping the GCM and the GSM into each executable program's address space so it is able to access shared libraries.

Embedded system having dynamically linked dynamic loader and method for

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

A system and method for loading dynamic data stored in read-only memory (ROM) is loaded into random access memory (RAM) only when it is being modified. Unmodified dynamic data is used from ROM saving valuable RAM space. Virtual memory page table entries are created for all dynamic data with the physical reference pointing to the dynamic data in ROM. Page table entries in a translation table for dynamic data in ROM include a virtual address to physical address mapping and are marked read-only causing a write-access exception if an attempt is made to write to or update the dynamic data. Write-access exceptions are intercepted, and a write-access exception caused by an attempt to write to dynamic data in ROM causes the system to allocate a dynamic data page in RAM, copy the ROM data to the RAM, update the page table entry to point to the RAM page rather than the ROM page, and finally to update the dynamic data now present in read-write RAM.

System and method for selectively enabling load-on-write of dynamic ROM

A method and apparatus for patching ROM pages using minimal RAM pages is accomplished by reserving a limited number of RAM pages which are shared to facilitate a patching process. The patching process begins when a flagged page of ROM (i.e., a page that is to be patched) is copied into one of the reserved pages of RAM. Having copied the flagged page, a patch file is accessed to retrieve updated code and outdated code of the flagged page. The process overwrites the outdated code with the updated code to produce a patched code. The patched code is read by a processor and is subsequently overwritten by another patched code that represents another flagged page of ROM.

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Austin, TX, United States of America

James Darrell Heath