I am using seaBIOS with QEMU and am attempting to hide a processor core (on an smp system) from the O.S. and then load a dedicated code on that core before boot. I have managed to hide one of the cores by decreasing CountCPUs (within smp.c) after running the ap core code, hence the BIOS load info for 1 less core on the mp table. 

However, I have not been able to figure out how to load the privileged code. My intuition was to load it when the hidden core enters protected mode before running kernel code. But I don't see where in the code the cores go into protected mode during boot. 

Can anyone give me some insight on how to proceed?

Thanks, 

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Jerry