+ EFI_STATUS Status;\r
+ EFI_PHYSICAL_ADDRESS BaseOfStack;\r
+ EFI_PHYSICAL_ADDRESS TopOfStack;\r
+ EFI_PHYSICAL_ADDRESS PageTables;\r
+\r
+ Status = PeiServicesAllocatePages (EfiBootServicesData, EFI_SIZE_TO_PAGES (STACK_SIZE), &BaseOfStack);\r
+ ASSERT_EFI_ERROR (Status);\r
+ \r
+ if (FeaturePcdGet(PcdDxeIplSwitchToLongMode)) {\r
+ //\r
+ // Compute the top of the stack we were allocated, which is used to load X64 dxe core. \r
+ // Pre-allocate a 32 bytes which confroms to x64 calling convention.\r
+ //\r
+ // The first four parameters to a function are passed in rcx, rdx, r8 and r9. \r
+ // Any further parameters are pushed on the stack. Furthermore, space (4 * 8bytes) for the \r
+ // register parameters is reserved on the stack, in case the called function \r
+ // wants to spill them; this is important if the function is variadic. \r
+ //\r
+ TopOfStack = BaseOfStack + EFI_SIZE_TO_PAGES (STACK_SIZE) * EFI_PAGE_SIZE - 32;\r
+\r
+ //\r
+ // X64 Calling Conventions requires that the stack must be aligned to 16 bytes\r
+ //\r
+ TopOfStack = (EFI_PHYSICAL_ADDRESS) (UINTN) ALIGN_POINTER (TopOfStack, 16);\r
+ //\r
+ // Load the GDT of Go64. Since the GDT of 32-bit Tiano locates in the BS_DATA\r
+ // memory, it may be corrupted when copying FV to high-end memory \r
+ //\r
+ LoadGo64Gdt();\r
+ //\r
+ // Limit to 36 bits of addressing for debug. Should get it from CPU\r
+ //\r
+ PageTables = CreateIdentityMappingPageTables (36);\r
+ //\r
+ // Go to Long Mode. Interrupts will not get turned on until the CPU AP is loaded.\r
+ // Call x64 drivers passing in single argument, a pointer to the HOBs.\r
+ //\r
+ ActivateLongMode (\r
+ PageTables, \r
+ (EFI_PHYSICAL_ADDRESS)(UINTN)(HobList.Raw), \r
+ TopOfStack,\r
+ 0x00000000,\r
+ DxeCoreEntryPoint\r
+ );\r
+ } else {\r
+ //\r
+ // Compute the top of the stack we were allocated. Pre-allocate a UINTN\r
+ // for safety.\r
+ //\r
+ TopOfStack = BaseOfStack + EFI_SIZE_TO_PAGES (STACK_SIZE) * EFI_PAGE_SIZE - CPU_STACK_ALIGNMENT;\r
+ TopOfStack = (EFI_PHYSICAL_ADDRESS) (UINTN) ALIGN_POINTER (TopOfStack, CPU_STACK_ALIGNMENT);\r
+\r
+ SwitchStack (\r
+ (SWITCH_STACK_ENTRY_POINT)(UINTN)DxeCoreEntryPoint,\r
+ HobList.Raw,\r
+ NULL,\r
+ (VOID *) (UINTN) TopOfStack\r
+ );\r
+ } \r