Computer system and startup method

A startup method of a computer on which a plurality of operating systems run,

• wherein the computer includes a processor, a first memory coupled to the processor, a second memory coupled to the processor, an I/O device coupled to the processor, and a storage device coupled to the processor,
• wherein the plurality of operating system include a first operating system and a second operating system,
• wherein the second memory stores a first hardware control unit for controlling hardware included in the computer, and executing start processing of the first operating system, in a case where the first operating system is started,
• wherein the storage device stores
• a first operating system image as an execution image of the first operating system,
• a first operating system boot loader for starting the first operating system,
• a second operating system image as an execution image of the second operating system,
• a second operating system boot loader for starting the second operating system,
• a second hardware control unit for controlling the hardware included in the computer and executing start processing of the second operating system, in a case where the second operating system is started, and
• an address rewrite unit for rewriting address data which an absolute address of a storage area in the first memory, the storage area stores information to be referred to by the second hardware control unit, and
• wherein the second hardware control unit includes a start unit for starting the second hardware control unit,
• the startup method including:
• a first step of writing, by the processor, in the first memory the first hardware control unit stored in the second memory, and executing the first hardware control unit, in a case of being powered on;
• a second step of reading, by the first hardware control unit executed by the processor, the second hardware control unit and the address rewrite unit from the storage device to write in a predetermined storage area of the first memory;
• a third step of obtaining, by the first hardware control unit executed by the processor, a head address of a storage area in which the start unit included in the second hardware control unit is stored, and writing the head address in the first memory as base address data;
• a fourth step of reading, by the first hardware control unit executed by the processor, the first operating system boot loader from the storage device to write in the first memory;
• a fifth step of starting, by the first hardware control unit executed by the processor, the first operating system boot loader written in the first memory;
• a sixth step of reading, by the first operating system boot loader executed by the processor, the first operating system image from the storage device to write in the first memory;
• a seventh step of starting, by the first operating system boot loader executed by the processor, the first operating system by executing the first operating system image written in the first memory;
• an eighth step of starting, by the first operating system executed by the processor, the address rewrite unit;
• a ninth step of obtaining, by the address rewrite unit executed by the processor, the base address data written in the first memory;
• a tenth step of obtaining, by the address rewrite unit executed by the processor, an address of a storage area, in which address data to be rewritten is stored, as a target address;
• an eleventh step of rewriting, by the address rewrite unit executed by the processor, the address data stored in the storage area corresponding to the obtained target address, based on the obtained base address data;
• a twelfth step of starting, by the address rewrite unit executed by the processor, the start unit;
• a thirteenth step of starting, by the start unit executed by the processor, the second hardware control unit by using rewritten address data;
• a fourteenth step of reading, by the second hardware control unit executed by the processor, the second operating system boot loader from the storage device to write in the first memory;
• a fifteenth step of starting, by the second hardware control unit executed by the processor, the second operating system boot loader written in the first memory;
• a sixteenth step of reading, by the second operating system boot loader executed by the processor, the second operating system image from the storage device to write in the first memory;
• and
• a seventeenth step of starting, by the second operating system boot loader executed by the processor, the second operating system by executing the second operating system image written in the first memory.