181 	 * On i386, place the gdt descriptor to be loaded from SIPI vector right after  in setup_rm_gdt()
202 	 * After relocating to the lowmem address pointed to by realmode_trampoline,  in setup_rm_gdt()
203 	 * the realmode GDT descriptor needs to contain the relocated address of  in setup_rm_gdt()
214 	 * 16-bit mode, the relocated address of ap_rm_gdt_descr needs to be stored at  in setup_rm_gdt()
215 	 * a location known to / accessible from the trampoline.  in setup_rm_gdt()
217 	 * Use the last two bytes of the trampoline page (REALMODE_GDT_LOWMEM) to store  in setup_rm_gdt()
218 	 * a pointer to relocated ap_rm_gdt_descr addr. This way, the trampoline code can  in setup_rm_gdt()
220 	 * and this relocated descriptor points to the relocated GDT.  in setup_rm_gdt()
225 	 * Set up a call gate to the 32-bit entrypoint (ap_start32) within GDT, since  in setup_rm_gdt()
227 	 * to be reachable from the SIPI vector.  in setup_rm_gdt()
229 	 * Since kvm-unit-tests builds with -shared, this location needs to be fetched  in setup_rm_gdt()
231 	 * prevents using a long jump to ap_start32 (`ljmpl $cs, $ap_start32`).  in setup_rm_gdt()
235 	 * 16-bit far return to work.  in setup_rm_gdt()
248 	 * later during boot, which does not need to follow this layout.  in setup_rm_gdt()