The DRIVER_IRQL_NOT_LESS_OR_EQUAL bug check has a value of 0x000000D1. This indicates that a kernel-mode driver attempted to access pageable memory at a process IRQL that was too high.
At the higher IRQL (levels), the kernel blocks attempts to perform the I/O operation, causing the request to fail, and subsequently a failure to access the memory.
The Interrupt Request Level (IRQL) is the priority ranking of an interrupt. Each processor has an IRQL setting that threads can raise or lower. Interrupts that occur at or below the processor's IRQL setting are masked and will not interfere with the current operation. Interrupts that occur above the processor's IRQL setting take precedence over the current operation.
There are two common forms:
- Inside - Windows SDK
- Microsoft Docs - Debugging Tools for Windows
- Microsoft Docs - DRIVER_IRQL_NOT_LESS_OR_EQUAL
- Microsoft Docs - Driver Verifier