System and method for performing hardware resource assignment in a large-scaled system

A resource assignment system includes a driver on an option ROM mounted on a PCI device, to perform hardware resources assignment under a Pre-Boot environment; and an OS driver to perform the hardware resource assignment under an OS environment. A BIOS includes a resource management table showing a range of an I/O space to be assigned to a bridge device in a layer higher than that of the PCI device which requests the I/O space; and an ACPI table used to notify a hardware configuration and data to use an extended I/O space to the OS. The resource management table includes a Pre-Boot table in which assignment of a first granularity to a Legacy-I/O space for a Pre-Boot environment is defined; and an OS table in which assignment of a second granularity to the extended I/O space for an OS environment is defined.