How Big Is a Physical Address?

This is a short aside in our virtual memory series. We have talked extensively about the size of a virtual address and the virtual address space, but we haven’t yet looked at the size of a physical address.

As you might expect, physical addresses on x86-64 are smaller than 64 bits. But they are also not necessarily the same size as virtual addresses. In this video, we look at how big physical addresses are, how you can check this on your own machine, and why different processors may expose different physical address sizes.

If you haven’t read the virtual memory article, do check it out. You can also download the ebook as a PDF from the link below.

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