| ;------------------------------------------------------------------------------ | |
| ; | |
| ; Copyright (c) 2013-2015 Intel Corporation. | |
| ; | |
| ; This program and the accompanying materials | |
| ; are licensed and made available under the terms and conditions of the BSD License | |
| ; which accompanies this distribution. The full text of the license may be found at | |
| ; http://opensource.org/licenses/bsd-license.php | |
| ; | |
| ; THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS, | |
| ; WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED. | |
| ; | |
| ; Module Name: | |
| ; | |
| ; Flat32.asm | |
| ; | |
| ; Abstract: | |
| ; | |
| ; This is the code that goes from real-mode to protected mode. | |
| ; It consumes the reset vector, configures the stack. | |
| ; | |
| ; | |
| ;------------------------------------------------------------------------------ | |
| ; | |
| ; Define assembler characteristics | |
| ; | |
| .586p | |
| .model flat, c | |
| ; | |
| ; Include processor definitions | |
| ; | |
| INCLUDE Platform.inc | |
| ; | |
| ; CR0 cache control bit definition | |
| ; | |
| CR0_CACHE_DISABLE EQU 040000000h | |
| CR0_NO_WRITE EQU 020000000h | |
| ; | |
| ; External and public declarations | |
| ; TopOfStack is used by C code | |
| ; SecStartup is the entry point to the C code | |
| ; Neither of these names can be modified without | |
| ; updating the C code. | |
| ; | |
| EXTRN PlatformSecLibStartup: NEAR | |
| EXTERNDEF C PcdGet32 (PcdEsramStage1Base):DWORD | |
| ; | |
| ; Contrary to the name, this file contains 16 bit code as well. | |
| ; | |
| _TEXT_REALMODE SEGMENT PARA PUBLIC USE16 'CODE' | |
| ASSUME CS:_TEXT_REALMODE, DS:_TEXT_REALMODE | |
| ;---------------------------------------------------------------------------- | |
| ; | |
| ; Procedure: _ModuleEntryPoint | |
| ; | |
| ; Input: None | |
| ; | |
| ; Output: None | |
| ; | |
| ; Destroys: Assume all registers | |
| ; | |
| ; Description: | |
| ; | |
| ; Transition to non-paged flat-model protected mode from a | |
| ; hard-coded GDT that provides exactly two descriptors. | |
| ; This is a bare bones transition to protected mode only | |
| ; used for a while in PEI and possibly DXE. | |
| ; | |
| ; After enabling protected mode, a far jump is executed to | |
| ; transfer to PEI using the newly loaded GDT. | |
| ; | |
| ; Return: None | |
| ; | |
| ;---------------------------------------------------------------------------- | |
| align 16 | |
| _ModuleEntryPoint PROC C PUBLIC | |
| ; | |
| ; Warm Reset (INIT#) check. | |
| ; | |
| mov si, 0F000h | |
| mov ds, si | |
| mov si, 0FFF0h | |
| cmp BYTE PTR [si], 0EAh ; Is it warm reset ? | |
| jne NotWarmReset ; JIf not. | |
| mov al, 08 | |
| mov dx, 0cf9h | |
| out dx, al | |
| mov al, 055h | |
| out 080h, al; | |
| jmp $ | |
| NotWarmReset: | |
| ; | |
| ; Load the GDT table in GdtDesc | |
| ; | |
| mov esi, OFFSET GdtDesc | |
| db 66h | |
| lgdt fword ptr cs:[si] | |
| ; | |
| ; Transition to 16 bit protected mode | |
| ; | |
| mov eax, cr0 ; Get control register 0 | |
| or eax, 00000003h ; Set PE bit (bit #0) & MP bit (bit #1) | |
| mov cr0, eax ; Activate protected mode | |
| ; | |
| ; Now we're in 16 bit protected mode | |
| ; Set up the selectors for 32 bit protected mode entry | |
| ; | |
| mov ax, SYS_DATA_SEL | |
| mov ds, ax | |
| mov es, ax | |
| mov fs, ax | |
| mov gs, ax | |
| mov ss, ax | |
| ; | |
| ; Transition to Flat 32 bit protected mode | |
| ; The jump to a far pointer causes the transition to 32 bit mode | |
| ; | |
| mov esi, offset ProtectedModeEntryLinearAddress | |
| jmp fword ptr cs:[si] | |
| _ModuleEntryPoint ENDP | |
| _TEXT_REALMODE ENDS | |
| .code | |
| ; | |
| ; Protected mode portion initializes stack, configures cache, and calls C entry point | |
| ; | |
| ;---------------------------------------------------------------------------- | |
| ; | |
| ; Procedure: ProtectedModeEntryPoint | |
| ; | |
| ; Input: Executing in 32 Bit Protected (flat) mode | |
| ; cs: 0-4GB | |
| ; ds: 0-4GB | |
| ; es: 0-4GB | |
| ; fs: 0-4GB | |
| ; gs: 0-4GB | |
| ; ss: 0-4GB | |
| ; | |
| ; Output: This function never returns | |
| ; | |
| ; Destroys: | |
| ; ecx | |
| ; edi | |
| ; esi | |
| ; esp | |
| ; | |
| ; Description: | |
| ; Perform any essential early platform initilaisation | |
| ; Setup a stack | |
| ; Call the main EDKII Sec C code | |
| ; | |
| ;---------------------------------------------------------------------------- | |
| ProtectedModeEntryPoint PROC NEAR C PUBLIC | |
| JMP32 stackless_EarlyPlatformInit | |
| ; | |
| ; Set up stack pointer | |
| ; | |
| mov esp, PcdGet32(PcdEsramStage1Base) | |
| mov esi, QUARK_ESRAM_MEM_SIZE_BYTES | |
| add esp, esi ; ESP = top of stack (stack grows downwards). | |
| ; | |
| ; Store the the BIST value in EBP | |
| ; | |
| mov ebp, 00h ; No processor BIST on Quark | |
| ; | |
| ; Push processor count to stack first, then BIST status (AP then BSP) | |
| ; | |
| mov eax, 1 | |
| cpuid | |
| shr ebx, 16 | |
| and ebx, 0000000FFh | |
| cmp bl, 1 | |
| jae PushProcessorCount | |
| ; | |
| ; Some processors report 0 logical processors. Effectively 0 = 1. | |
| ; So we fix up the processor count | |
| ; | |
| inc ebx | |
| PushProcessorCount: | |
| push ebx | |
| ; | |
| ; We need to implement a long-term solution for BIST capture. For now, we just copy BSP BIST | |
| ; for all processor threads | |
| ; | |
| xor ecx, ecx | |
| mov cl, bl | |
| PushBist: | |
| push ebp | |
| loop PushBist | |
| ; | |
| ; Pass Control into the PEI Core | |
| ; | |
| call PlatformSecLibStartup | |
| ; | |
| ; PEI Core should never return to here, this is just to capture an invalid return. | |
| ; | |
| jmp $ | |
| ProtectedModeEntryPoint ENDP | |
| ;---------------------------------------------------------------------------- | |
| ; | |
| ; Procedure: stackless_EarlyPlatformInit | |
| ; | |
| ; Input: esp - Return address | |
| ; | |
| ; Output: None | |
| ; | |
| ; Destroys: | |
| ; eax | |
| ; ecx | |
| ; dx | |
| ; ebp | |
| ; | |
| ; Description: | |
| ; Any essential early platform initialisation required: | |
| ; (1) Disable Cache | |
| ; (2) Disable NMI's/SMI's | |
| ; (3) Setup HMBOUND (defines what memory accesses go to MMIO/RAM) | |
| ; (4) Setup eSRAM (provide early memory to the system) | |
| ; (5) Setup PCIEXBAR access mechanism | |
| ; (6) Open up full SPI flash decode | |
| ; | |
| ;---------------------------------------------------------------------------- | |
| stackless_EarlyPlatformInit PROC NEAR C PUBLIC | |
| ; | |
| ; Save return address | |
| ; | |
| mov ebp, esp | |
| ; | |
| ; Ensure cache is disabled. | |
| ; | |
| mov eax, cr0 | |
| or eax, CR0_CACHE_DISABLE + CR0_NO_WRITE | |
| invd | |
| mov cr0, eax | |
| ; | |
| ; Disable NMI | |
| ; Good convention suggests you should read back RTC data port after | |
| ; accessing the RTC index port. | |
| ; | |
| mov al, NMI_DISABLE | |
| mov dx, RTC_INDEX | |
| out dx, al | |
| mov dx, RTC_DATA | |
| in al, dx | |
| ; | |
| ; Disable SMI (Disables SMI wire, not SMI messages) | |
| ; | |
| mov ecx, (OPCODE_SIDEBAND_REG_READ SHL SB_OPCODE_FIELD) OR (HOST_BRIDGE_PORT_ID SHL SB_PORT_FIELD) OR (HMISC2_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Read | |
| and eax, NOT (SMI_EN) | |
| mov ecx, (OPCODE_SIDEBAND_REG_WRITE SHL SB_OPCODE_FIELD) OR (HOST_BRIDGE_PORT_ID SHL SB_PORT_FIELD) OR (HMISC2_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| ; | |
| ; Before we get going, check SOC Unit Registers to see if we are required to issue a warm/cold reset | |
| ; | |
| mov ecx, (OPCODE_SIDEBAND_ALT_REG_READ SHL SB_OPCODE_FIELD) OR (SOC_UNIT_PORT_ID SHL SB_PORT_FIELD) OR (CFGNONSTICKY_W1_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Read | |
| and eax, FORCE_WARM_RESET | |
| jz TestForceColdReset ; Zero means bit clear, we're not requested to warm reset so continue as normal | |
| jmp IssueWarmReset | |
| TestForceColdReset: | |
| mov ecx, (OPCODE_SIDEBAND_ALT_REG_READ SHL SB_OPCODE_FIELD) OR (SOC_UNIT_PORT_ID SHL SB_PORT_FIELD) OR (CFGSTICKY_W1_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Read | |
| and eax, FORCE_COLD_RESET | |
| jz TestHmboundLock ; Zero means bit clear, we're not requested to cold reset so continue as normal | |
| jmp IssueColdReset | |
| ; | |
| ; Before setting HMBOUND, check it's not locked | |
| ; | |
| TestHmboundLock: | |
| mov ecx, (OPCODE_SIDEBAND_REG_READ SHL SB_OPCODE_FIELD) OR (HOST_BRIDGE_PORT_ID SHL SB_PORT_FIELD) OR (HMBOUND_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Read | |
| and eax, HMBOUND_LOCK | |
| jz ConfigHmbound ; Zero means bit clear, we have the config we want so continue as normal | |
| ; | |
| ; Failed to config - store sticky bit debug | |
| ; | |
| mov ecx, (OPCODE_SIDEBAND_ALT_REG_READ SHL SB_OPCODE_FIELD) OR (SOC_UNIT_PORT_ID SHL SB_PORT_FIELD) OR (CFGSTICKY_RW_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Read | |
| or eax, RESET_FOR_HMBOUND_LOCK ; Set the bit we're interested in | |
| mov ecx, (OPCODE_SIDEBAND_ALT_REG_WRITE SHL SB_OPCODE_FIELD) OR (SOC_UNIT_PORT_ID SHL SB_PORT_FIELD) OR (CFGSTICKY_RW_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| jmp IssueWarmReset | |
| ; | |
| ; Set up the HMBOUND register | |
| ; | |
| ConfigHmbound: | |
| mov eax, HMBOUND_ADDRESS ; Data (Set HMBOUND location) | |
| mov ecx, (OPCODE_SIDEBAND_REG_WRITE SHL SB_OPCODE_FIELD) OR (HOST_BRIDGE_PORT_ID SHL SB_PORT_FIELD) OR (HMBOUND_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| ; | |
| ; Enable interrupts to Remote Management Unit when a IMR/SMM/HMBOUND violation occurs. | |
| ; | |
| mov eax, ENABLE_IMR_INTERRUPT ; Data (Set interrupt enable mask) | |
| mov ecx, (OPCODE_SIDEBAND_REG_WRITE SHL SB_OPCODE_FIELD) OR (MEMORY_MANAGER_PORT_ID SHL SB_PORT_FIELD) OR (BIMRVCTL_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| ; | |
| ; Set eSRAM address | |
| ; | |
| mov eax, PcdGet32 (PcdEsramStage1Base) ; Data (Set eSRAM location) | |
| shr eax, 18h ; Data (Set eSRAM location) | |
| add eax, BLOCK_ENABLE_PG | |
| mov ecx, (OPCODE_SIDEBAND_REG_WRITE SHL SB_OPCODE_FIELD) OR (MEMORY_MANAGER_PORT_ID SHL SB_PORT_FIELD) OR (ESRAMPGCTRL_BLOCK_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| ; | |
| ; Check that we're not blocked from setting the config that we want. | |
| ; | |
| mov ecx, (OPCODE_SIDEBAND_REG_READ SHL SB_OPCODE_FIELD) OR (MEMORY_MANAGER_PORT_ID SHL SB_PORT_FIELD) OR (ESRAMPGCTRL_BLOCK_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Read | |
| and eax, BLOCK_ENABLE_PG | |
| jnz ConfigPci ; Non-zero means bit set, we have the config we want so continue as normal | |
| ; | |
| ; Failed to config - store sticky bit debug | |
| ; | |
| mov ecx, (OPCODE_SIDEBAND_ALT_REG_READ SHL SB_OPCODE_FIELD) OR (SOC_UNIT_PORT_ID SHL SB_PORT_FIELD) OR (CFGSTICKY_RW_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Read | |
| or eax, RESET_FOR_ESRAM_LOCK ; Set the bit we're interested in | |
| mov ecx, (OPCODE_SIDEBAND_ALT_REG_WRITE SHL SB_OPCODE_FIELD) OR (SOC_UNIT_PORT_ID SHL SB_PORT_FIELD) OR (CFGSTICKY_RW_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| jmp IssueWarmReset | |
| ; | |
| ; Enable PCIEXBAR | |
| ; | |
| ConfigPci: | |
| mov eax, (EC_BASE + EC_ENABLE) ; Data | |
| mov ecx, (OPCODE_SIDEBAND_REG_WRITE SHL SB_OPCODE_FIELD) OR (MEMORY_ARBITER_PORT_ID SHL SB_PORT_FIELD) OR (AEC_CTRL_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| mov eax, (EC_BASE + EC_ENABLE) ; Data | |
| mov ecx, (OPCODE_SIDEBAND_REG_WRITE SHL SB_OPCODE_FIELD) OR (HOST_BRIDGE_PORT_ID SHL SB_PORT_FIELD) OR (HECREG_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| ; | |
| ; Open up full 8MB SPI decode | |
| ; | |
| mov ebx, PCI_CFG OR (ILB_PFA SHL 8) OR BDE ; PCI Configuration address | |
| mov eax, DECODE_ALL_REGIONS_ENABLE | |
| JMP32 stackless_PCIConfig_Write | |
| ; | |
| ; Enable NMI operation | |
| ; Good convention suggests you should read back RTC data port after | |
| ; accessing the RTC index port. | |
| ; | |
| mov al, NMI_ENABLE | |
| mov dx, RTC_INDEX | |
| out dx, al | |
| mov dx, RTC_DATA | |
| in al, dx | |
| ; | |
| ; Clear Host Bridge SMI, NMI, INTR fields | |
| ; | |
| mov ecx, (OPCODE_SIDEBAND_REG_READ SHL SB_OPCODE_FIELD) OR (HOST_BRIDGE_PORT_ID SHL SB_PORT_FIELD) OR (HLEGACY_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Read | |
| and eax, NOT(NMI + SMI + INTR) ; Clear NMI, SMI, INTR fields | |
| mov ecx, (OPCODE_SIDEBAND_REG_WRITE SHL SB_OPCODE_FIELD) OR (HOST_BRIDGE_PORT_ID SHL SB_PORT_FIELD) OR (HLEGACY_OFFSET SHL SB_ADDR_FIELD) | |
| JMP32 stackless_SideBand_Write | |
| ; | |
| ; Restore return address | |
| ; | |
| mov esp, ebp | |
| RET32 | |
| IssueWarmReset: | |
| ; | |
| ; Issue Warm Reset request to Remote Management Unit via iLB | |
| ; | |
| mov ax, CF9_WARM_RESET | |
| mov dx, ILB_RESET_REG | |
| out dx, ax | |
| jmp $ ; Stay here until we are reset. | |
| IssueColdReset: | |
| ; | |
| ; Issue Cold Reset request to Remote Management Unit via iLB | |
| ; | |
| mov ax, CF9_COLD_RESET | |
| mov dx, ILB_RESET_REG | |
| out dx, ax | |
| jmp $ ; Stay here until we are reset. | |
| stackless_EarlyPlatformInit ENDP | |
| ;---------------------------------------------------------------------------- | |
| ; | |
| ; Procedure: stackless_SideBand_Read | |
| ; | |
| ; Input: esp - return address | |
| ; ecx[15:8] - Register offset | |
| ; ecx[23:16] - Port ID | |
| ; ecx[31:24] - Opcode | |
| ; | |
| ; Output: eax - Data read | |
| ; | |
| ; Destroys: | |
| ; eax | |
| ; ebx | |
| ; cl | |
| ; esi | |
| ; | |
| ; Description: | |
| ; Perform requested sideband read | |
| ; | |
| ;---------------------------------------------------------------------------- | |
| stackless_SideBand_Read PROC NEAR C PUBLIC | |
| mov esi, esp ; Save the return address | |
| ; | |
| ; Load the SideBand Packet Register to generate the transaction | |
| ; | |
| mov ebx, PCI_CFG OR (HOST_BRIDGE_PFA SHL 8) OR MESSAGE_BUS_CONTROL_REG ; PCI Configuration address | |
| mov cl, (ALL_BYTE_EN SHL SB_BE_FIELD) ; Set all Byte Enable bits | |
| xchg eax, ecx | |
| JMP32 stackless_PCIConfig_Write | |
| xchg eax, ecx | |
| ; | |
| ; Read the SideBand Data Register | |
| ; | |
| mov ebx, PCI_CFG OR (HOST_BRIDGE_PFA SHL 8) OR MESSAGE_DATA_REG ; PCI Configuration address | |
| JMP32 stackless_PCIConfig_Read | |
| mov esp, esi ; Restore the return address | |
| RET32 | |
| stackless_SideBand_Read ENDP | |
| ;---------------------------------------------------------------------------- | |
| ; | |
| ; Procedure: stackless_SideBand_Write | |
| ; | |
| ; Input: esp - return address | |
| ; eax - Data | |
| ; ecx[15:8] - Register offset | |
| ; ecx[23:16] - Port ID | |
| ; ecx[31:24] - Opcode | |
| ; | |
| ; Output: None | |
| ; | |
| ; Destroys: | |
| ; ebx | |
| ; cl | |
| ; esi | |
| ; | |
| ; Description: | |
| ; Perform requested sideband write | |
| ; | |
| ; | |
| ;---------------------------------------------------------------------------- | |
| stackless_SideBand_Write PROC NEAR C PUBLIC | |
| mov esi, esp ; Save the return address | |
| ; | |
| ; Load the SideBand Data Register with the data | |
| ; | |
| mov ebx, PCI_CFG OR (HOST_BRIDGE_PFA SHL 8) OR MESSAGE_DATA_REG ; PCI Configuration address | |
| JMP32 stackless_PCIConfig_Write | |
| ; | |
| ; Load the SideBand Packet Register to generate the transaction | |
| ; | |
| mov ebx, PCI_CFG OR (HOST_BRIDGE_PFA SHL 8) OR MESSAGE_BUS_CONTROL_REG ; PCI Configuration address | |
| mov cl, (ALL_BYTE_EN SHL SB_BE_FIELD) ; Set all Byte Enable bits | |
| xchg eax, ecx | |
| JMP32 stackless_PCIConfig_Write | |
| xchg eax, ecx | |
| mov esp, esi ; Restore the return address | |
| RET32 | |
| stackless_SideBand_Write ENDP | |
| ;---------------------------------------------------------------------------- | |
| ; | |
| ; Procedure: stackless_PCIConfig_Write | |
| ; | |
| ; Input: esp - return address | |
| ; eax - Data to write | |
| ; ebx - PCI Config Address | |
| ; | |
| ; Output: None | |
| ; | |
| ; Destroys: | |
| ; dx | |
| ; | |
| ; Description: | |
| ; Perform a DWORD PCI Configuration write | |
| ; | |
| ;---------------------------------------------------------------------------- | |
| stackless_PCIConfig_Write PROC NEAR C PUBLIC | |
| ; | |
| ; Write the PCI Config Address to the address port | |
| ; | |
| xchg eax, ebx | |
| mov dx, PCI_ADDRESS_PORT | |
| out dx, eax | |
| xchg eax, ebx | |
| ; | |
| ; Write the PCI DWORD Data to the data port | |
| ; | |
| mov dx, PCI_DATA_PORT | |
| out dx, eax | |
| RET32 | |
| stackless_PCIConfig_Write ENDP | |
| ;---------------------------------------------------------------------------- | |
| ; | |
| ; Procedure: stackless_PCIConfig_Read | |
| ; | |
| ; Input: esp - return address | |
| ; ebx - PCI Config Address | |
| ; | |
| ; Output: eax - Data read | |
| ; | |
| ; Destroys: | |
| ; eax | |
| ; dx | |
| ; | |
| ; Description: | |
| ; Perform a DWORD PCI Configuration read | |
| ; | |
| ;---------------------------------------------------------------------------- | |
| stackless_PCIConfig_Read PROC NEAR C PUBLIC | |
| ; | |
| ; Write the PCI Config Address to the address port | |
| ; | |
| xchg eax, ebx | |
| mov dx, PCI_ADDRESS_PORT | |
| out dx, eax | |
| xchg eax, ebx | |
| ; | |
| ; Read the PCI DWORD Data from the data port | |
| ; | |
| mov dx, PCI_DATA_PORT | |
| in eax, dx | |
| RET32 | |
| stackless_PCIConfig_Read ENDP | |
| ; | |
| ; ROM-based Global-Descriptor Table for the Tiano PEI Phase | |
| ; | |
| align 16 | |
| PUBLIC BootGdtTable | |
| ; | |
| ; GDT[0]: 0x00: Null entry, never used. | |
| ; | |
| NULL_SEL equ $ - GDT_BASE ; Selector [0] | |
| GDT_BASE: | |
| BootGdtTable DD 0 | |
| DD 0 | |
| ; | |
| ; Linear data segment descriptor | |
| ; | |
| LINEAR_SEL equ $ - GDT_BASE ; Selector [0x8] | |
| DW 0FFFFh ; limit 0xFFFF | |
| DW 0 ; base 0 | |
| DB 0 | |
| DB 092h ; present, ring 0, data, expand-up, writable | |
| DB 0CFh ; page-granular, 32-bit | |
| DB 0 | |
| ; | |
| ; Linear code segment descriptor | |
| ; | |
| LINEAR_CODE_SEL equ $ - GDT_BASE ; Selector [0x10] | |
| DW 0FFFFh ; limit 0xFFFF | |
| DW 0 ; base 0 | |
| DB 0 | |
| DB 09Bh ; present, ring 0, data, expand-up, not-writable | |
| DB 0CFh ; page-granular, 32-bit | |
| DB 0 | |
| ; | |
| ; System data segment descriptor | |
| ; | |
| SYS_DATA_SEL equ $ - GDT_BASE ; Selector [0x18] | |
| DW 0FFFFh ; limit 0xFFFF | |
| DW 0 ; base 0 | |
| DB 0 | |
| DB 093h ; present, ring 0, data, expand-up, not-writable | |
| DB 0CFh ; page-granular, 32-bit | |
| DB 0 | |
| ; | |
| ; System code segment descriptor | |
| ; | |
| SYS_CODE_SEL equ $ - GDT_BASE ; Selector [0x20] | |
| DW 0FFFFh ; limit 0xFFFF | |
| DW 0 ; base 0 | |
| DB 0 | |
| DB 09Ah ; present, ring 0, data, expand-up, writable | |
| DB 0CFh ; page-granular, 32-bit | |
| DB 0 | |
| ; | |
| ; Spare segment descriptor | |
| ; | |
| SYS16_CODE_SEL equ $ - GDT_BASE ; Selector [0x28] | |
| DW 0FFFFh ; limit 0xFFFF | |
| DW 0 ; base 0 | |
| DB 0Fh | |
| DB 09Bh ; present, ring 0, code, expand-up, writable | |
| DB 00h ; byte-granular, 16-bit | |
| DB 0 | |
| ; | |
| ; Spare segment descriptor | |
| ; | |
| SYS16_DATA_SEL equ $ - GDT_BASE ; Selector [0x30] | |
| DW 0FFFFh ; limit 0xFFFF | |
| DW 0 ; base 0 | |
| DB 0 | |
| DB 093h ; present, ring 0, data, expand-up, not-writable | |
| DB 00h ; byte-granular, 16-bit | |
| DB 0 | |
| ; | |
| ; Spare segment descriptor | |
| ; | |
| SPARE5_SEL equ $ - GDT_BASE ; Selector [0x38] | |
| DW 0 ; limit 0xFFFF | |
| DW 0 ; base 0 | |
| DB 0 | |
| DB 0 ; present, ring 0, data, expand-up, writable | |
| DB 0 ; page-granular, 32-bit | |
| DB 0 | |
| GDT_SIZE EQU $ - BootGDTtable ; Size, in bytes | |
| ; | |
| ; GDT Descriptor | |
| ; | |
| GdtDesc: ; GDT descriptor | |
| DW GDT_SIZE - 1 ; GDT limit | |
| DD OFFSET BootGdtTable ; GDT base address | |
| ProtectedModeEntryLinearAddress LABEL FWORD | |
| ProtectedModeEntryLinearOffset LABEL DWORD | |
| DD OFFSET ProtectedModeEntryPoint ; Offset of our 32 bit code | |
| DW LINEAR_CODE_SEL | |
| END |