## Physical Device Driver Reference

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### Resources

The hardware resources managed by the Resource Manager are:

I/O Port Ranges
IRQ Levels
DMA Channels
Memory Regions
Timer Channels

Driver writers are encouraged to identify their hardware settings during driver initialization directly rather than relying on the end-user to provide this information.

The Resource Manager services facilitate this process by identifying resources (I/O Ports, DMA Channels, and IRQ Levels) that are already claimed by drivers and have been initialized previously. A driver using the Resource Management calls can avoid inadvertently corrupting the state of adapters that were initialized by previously loaded drivers.

When resources are assigned, various levels of sharing are allowed. The type of sharing allowed depends on the underlying characteristics of the devices. Resource sharing options are discussed in Managing System Resources.