Plug and Play BIOS Specification

Plug and Play BIOS Specification 1.0A Page 25
The device node attributes provide additional information about the state of the device and the capabilities
of the device. This bit-field is defined as follows:
bit 15-9:reserved (0)
bits 8:7 0:0=device can only be configured for next boot (static)
0:1=device can be configured at runtime (dynamically)
1:0=Reserved
1:1=device can only be configured at runtime (dynamically)
bit 6: 0=device is not a removable system device
1=device is a removable system device
bit 5: 0=device is not a docking station device
1=device is a docking station device
bit 4: 0=device is not capable of being primary Initial Program Load (IPL) device
1=device is capable of being primary IPL device
bit 3: 0=device is not capable of being primary input device
1=device is capable of being primary input device
bit 2: 0=device is not capable of being primary output device
1=device is capable of being primary output device
bit 1: 0=device is configurable
1=device is not configurable
bit 0: 0=device can be disabled
1=device cannot be disabled
Bit 0 specifies whether the device can be disabled or not. If the device is disabled, it is assumed that the
system resources that the device was using are available for use by other devices.
Bit 1 indicates that the device is configurable. This implies that the system device node provides the
resource requirements for the device in the Possible resource configuration descriptor block. If the
device node does not specify the resource requirements or the device does not have any alternate system
resource requirements, bit 1 must be set to indicate that the device is not configurable.
Bits 2-4 identify the capability of the device being designated as a boot device.
Bit 5 indicates that the device resides on a docking station or convenience base.
Bit 6 indicates that the device node represents a device that is removable on the base system unit, such as
a removable floppy drive.
Bits 8:7 use three of the four possible states to indicate if the device node can be configured dynamically,
configured statically only for next boot or configured dynamically only. The fourth state is reserved.
Allocated resource configuration descriptor block:
The allocated resource descriptor block describes the system resources allocated to this device. The format
of the data contained in this block follows the format defined in the Plug and Play ISA Specification
under the section labeled Plug and Play Resources. The resource data is provided as a series of data
structures with each of the resource data structures having a unique tag or identifier. These are the
resource descriptors which specifically describe the standard PC system resources, such as Memory, I/O
addresses, IRQs, and DMA channels.
Possible resource configuration descriptor block:
The alternative resource selections that a particular device can support can be obtained from the data
contained in this block. The format of the data in this block follows the same format as the allocated
resource descriptor block. Refer to the Plug and Play ISA Specification under the section labeled Plug
and Play Resources for a description of the data structures that make up the resource descriptor blocks.
These are the resource descriptors which specifically describe the standard PC system resources, such as
Memory, I/O addresses, IRQs, and DMA channels.
The information in this block can be used by the system BIOS and/or system software for selecting a
conflict free resource allocation for this device without user intervention. The data in this block is
optional. If this information is not provided in this structure, it can optionally be provided in a
configuration file for the systemboard that defines the configuration information for the embedded
devices. If the possible resource configurations are not specified in either place the device is assumed to