Knowledge

ERROR_BAD_MCFG_TABLE - 791 (0x317)

The resources required for this device conflict with the MCFG table.

Updated: Feb 21, 2026

Technical Background

The ERROR_BAD_MCFG_TABLE error code, with the numeric value of 791 and the hexadecimal representation of 0x317, indicates a conflict between the resources required by a device and the Memory Configuration Table (MCFG) in the system. The MCFG table is used to identify memory-mapped I/O regions for devices on an Intel-based platform.

Error Details

This error typically occurs during the initialization or configuration of a device driver, where the system detects that the resources requested by the device are not compatible with the information provided in the MCFG table. This can include issues such as overlapping memory ranges, incorrect resource allocation, or misconfiguration of the device's I/O addresses.

Common Causes

  • Incorrect Device Configuration: The device driver may have specified an I/O address range that conflicts with the ranges defined in the MCFG table.
  • Resource Overlap: There might be a conflict between the resources requested by multiple devices, leading to overlapping memory or I/O regions.
  • MCFG Table Inaccuracy: The MCFG table itself might contain incorrect information due to hardware issues or misconfiguration during system setup.

Real-World Context

This error can occur in scenarios where a device driver attempts to initialize and allocate resources that are already in use by another component of the system. For example, if a network adapter requests an I/O address range that overlaps with that of a storage controller, this conflict would be detected and result in the ERROR_BAD_MCFG_TABLE error.

Is This Error Critical?

The severity of this error depends on the specific device and its role within the system. In some cases, it may prevent the device from functioning correctly or at all. However, in other scenarios, the system might be able to work around the issue by reconfiguring resources or using alternative methods.

How to Diagnose

  1. Review Operation Context: Examine the context in which the error occurred, such as during driver installation or device initialization.
  2. Validate Parameters: Check the parameters passed to the device driver for any inconsistencies or errors that might lead to resource conflicts.
  3. Confirm Object Types: Verify that the correct object types are being used and that they match the expected configuration in the MCFG table.
  4. Verify Input Data: Ensure that all input data, such as I/O addresses and memory ranges, is accurate and does not conflict with existing system configurations.
  5. Check Limits or Constraints: Confirm that the device's resource requirements do not exceed the limits defined by the system architecture or hardware specifications.

How to Resolve

  1. Correct Parameter Usage: Ensure that all parameters passed to the device driver are correct and do not conflict with other devices.
  2. Adjust Operation Context: Modify the initialization context of the device if necessary, ensuring that it does not overlap with existing resources.
  3. Restore Data: If the MCFG table is found to be incorrect or corrupted, restore its contents from a known good configuration or perform a system reset.
  4. Retry Operation with Valid Inputs: Attempt to initialize the device again using valid and non-conflicting resource allocations.

Developer Notes

When developing device drivers, it is crucial to ensure that all resource requests are accurately reflected in the MCFG table and do not conflict with existing configurations. Regularly updating and validating the MCFG table can help prevent such errors from occurring.

Related Errors

  • ERROR_MAPPED_DEVICE (0x6D2): Indicates a failure related to device mapping, which might be indirectly related to resource conflicts.
  • STATUS_RESOURCE_LOCKED (0xC0000195): Suggests that resources are already locked by another component, potentially leading to conflicts with the MCFG table.

FAQ

Q: What does the ERROR_BAD_MCFG_TABLE error mean?

A: It indicates a conflict between the device's resource requirements and the information provided in the MCFG table.

Q: How can I prevent this error from occurring?

A: Ensure that all device drivers are correctly configured, and regularly update the MCFG table to reflect any changes in system hardware or configuration.

Q: Can this error be resolved by simply restarting the system?

A: In some cases, a system restart might help resolve temporary issues. However, for persistent conflicts, more detailed investigation is required.

Summary

The ERROR_BAD_MCFG_TABLE error code highlights a conflict between device resources and the MCFG table. By understanding its causes and implementing appropriate diagnostic and resolution steps, developers can effectively manage this issue to ensure smooth system operation.