CODEWITHSUNDEEP
linuxmemorymemory-managementlinux-kernel
xdxdxd
xdxdxd

Reputation: 116

Physical address exceeding physical memory available on the system

I am allocating a huge page of size 1 GB on a Linux system. When I convert the base address of that hugepage (using pagemap API of Linux), the physical base address returned is 0x200000000 --> 34th bit is set which makes this 16GB. However, I have 8 GB RAM inserted to my system. So I expect the returned physical address to be in range of 0-33th bit set. How can the physical address exceed my physical RAM inserted on the system?

Upvotes: 1

Views: 215

Answers (1)

sawdust
sawdust

Reputation: 17067

How can the physical address exceed my physical RAM inserted on the system?

You are (incorrectly) assuming that the start of the main memory is located at physical address 0 and/or is contiguous. That is not necessarily true (especially on non-x86 systems such as ARM).

Check the /proc/iomem file on your Linux system for information on how physical memory addresses are used.

Upvotes: 2

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