When opening a memory dump file generated on certain systems using the Debugging Tools for Windows (windbg.exe), the following message may appear:

WARNING: Dump header physical memory block has been truncated.
Some valid physical pages may be inaccessible.

While this warning has multiple possible causes, one reason this may occur is due to the physical memory layout of the system which generated the dump file.

The crash dump format has a limit of 42 (64-bit) and 86 (32-bit) physical address ranges. On certain systems, the BIOS firmware memory map may contain more than this number of non-contiguous regions. When a dump file is generated on this system, only the first 42 (64-bit) or 86 (32-bit) memory regions will be saved to the file. Kernel and Complete memory dumps from a Windows system may not contain all the memory from the system.

To prevent the issue, the OEM of the affected system would need to modify the firmware memory map to ensure the number of physical contiguous physical memory regions exposed to the Operating System does not exceed the limits previously noted.

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