HailMary, I looked at chapter 4 (Vol. 2). I don't see anything which contradicts the guidance in Chapter 1, p.9 (Vol. 1) which states the following:
As with 64-bit mode, compatibility mode is enabled by the operating system on an individual code-segment basis. Unlike 64-bit mode, however, x86 segmentation functions the same as in the legacy x86 architecture, using 16-bit or 32-bit protectedmode semantics. From the application viewpoint, compatibility mode looks like the legacy x86 protected-mode environment. From the operating-system viewpoint, however, address translation, interrupt and exception handling, and system data structures use the 64-bit long-mode mechanisms.
The chapter you referenced goes into this in more detail. I'm not sure of your point, in response to my statement here:
"The segmentation which is supported in Compatibility Mode is an emulation layer which translates to the same 64-bit mechanisms used in 64-bit mode. The fundamental design of Long Mode is not at all dependent on any Protected Mode segmentation."
That is not how I interpreted it. Read Chapter 4 in Volume 2 (System Programming Manual), and let me know if you still think this is the case afterwards.
Please tell me if there is a specific section within that chapter which I should be looking at.
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