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Looks like you will still be able to run 32 bit user mode applications under a 64 bit kernel. I'm not sure, but I think 32 bit guest kernels get the ax as well.

" 3.3 Removal of 16-Bit and 32-Bit Protected Mode

16-bit and 32-bit protected mode are not supported anymore and cannot be entered. The CPU always operates in long mode. The 32-bit submode of Intel64 (compatibility mode) still exists. ... "

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> I'm not sure, but I think 32 bit guest kernels get the ax as well.

This is somewhat beyond my knowledge of system programming, but my read is that it's just possible to support 32-bit guest kernels in the VM with some more emulation of the de-supported instructions. I don't know how many of those instructions already cause VM exits.

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