Super User is a question and answer site for computer enthusiasts and power users. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

My PC has 8GB of memory installed and is running Win 7 64-bit. I ran a tool named fwmemmap that shows the firmware memory map for the system but it's showing around 60MB more than is physically installed -

enter image description here

The total of all type 1 (memory) adds up to 8142MB which is correct and is also correlated in Windows -

enter image description here

I would have expected the total of the type 2 (reserved) and type 4 (ACPI NVS) memory to equal 50 MB to bring the total to 8192 MB but it equals around 110MB? Which is more than is physically installed.

Is anyone able to explain why this is?

Any help would be appreciated,


share|improve this question
It reads like those are reserved address ranges, not memory. – Oliver Salzburg Apr 7 '14 at 21:52
@OliverSalzburg Thanks for the comment. Is the total reserved address higher than the physical memory installed becuase addresses for I/O devices are being counted? – RJSmith92 Apr 8 '14 at 11:47
To make sense of the output, we would need to know what this tool actually is and what it's supposed to do. So far you've simply presented a list of addresses and an assumption you've made based on observing them. – Oliver Salzburg Apr 8 '14 at 12:05
The tool is called fwmemmap and shows the memory map that is created by the firmware. – RJSmith92 Apr 8 '14 at 12:07
up vote 0 down vote accepted

From my understanding, the output of fwmemmap applies to a more general understanding of memory than physical memory.

Only some of those address ranges actually map to physical memory, as pointed out on the website:

Ranges that are addressable as RAM are marked “memory”. To interpret other values in the Type column, refer to the definition of int 15h function E820h in the Advanced Configuration and Power Interface (ACPI) Specification, Section 14, System Address Map Interfaces. Note that the map has holes: int 15h function E820h does not report “standard PC address ranges” or areas of address space that are used “for the memory mapping of PCI devices, ISA Option ROMs, and ISA Plug and Play cards”.

share|improve this answer

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .