Patent
1997-09-30
1999-06-15
Kriess, Kevin A.
395821, G06F 906, G06F 1300
Patent
active
059130580
ABSTRACT:
A system and method for using real mode BIOS calls to load an executable program for execution on a dedicated I/O processor before device drivers which communicate with the I/O processor have been loaded by an operating system. In the preferred embodiment, the system comprises a plurality of x86 processors coupled to a system memory. One of the x86 processors is designated as a dedicated I/O processor. A storage device stores an operating system for execution on the remaining processors, an executable program for executing on the dedicated I/O processor, such as a real-time kernel, and a device driver which is operable to execute on the remaining processors and to communicate with the real-time kernel executing on the I/O processor to perform I/o operations on an I/O device. The storage device also stores a loader program which is loaded by the operating system executing on a first of the remaining processors early in the process of booting the operating system. The loader program executing on the first processor creates a real mode interface in order to switch the first processor to real mode so that a real mode code portion of the loader can execute BIOS INT13 disk requests to read the real-time kernel from the storage device. Creating the real mode interface comprises saving the protected mode state of the first processor and of the system's interrupt control logic. After saving the states of the first processor and interrupt control logic, the loader program programs the interrupt control logic to simulate a real mode environment. The loader program also provides a "tiled mapping" of memory addresses such that the transition may be made from real mode to protected mode and vice versa to facilitate the x86 processor real mode and protected mode physical address computation differences.
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Compaq Computer Corp.
Daffer Kevin L.
Kriess Kevin A.
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