BSOD 69 (INSUFFICIENT_SYSTEM_MAP_REGS): causes and diagnosis

Status / error code:		Category:

Constant name:
Source:		Operating System:
Description: A driver or DMA path exhausted required system map registers for an I/O transfer.

Could be also:
Constant	Type	OS
ERROR_TOO_MANY_SESS	Win32 error	Windows
ESRMNT	errno	Linux
EDQUOT	errno	Mac
ESRMNT	errno	Solaris

INSUFFICIENT_SYSTEM_MAP_REGS

System map register exhaustion

INSUFFICIENT_SYSTEM_MAP_REGS is bug check code 0x00000045. System map registers are used in DMA and memory-mapping paths that let devices address buffers. This bug check points to a driver or platform path that could not obtain enough mapping resources for the requested transfer.

How to read it in a dump

Look for a storage, network, display, or bus-mastering device driver on the stack.
The transfer size and DMA adapter state matter more than the symbolic code alone.
Repeated failures can indicate a driver that leaks map registers or builds unsupported scatter/gather requests.

What to check

Audit DMA transaction sizes, scatter/gather lists, and cancellation paths.
Use Driver Verifier DMA checking for a suspect driver.
Check whether the issue appears only with high I/O load or specific hardware.

References

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