[mirror_edk2.git] / IntelFsp2WrapperPkg / Library / SecFspWrapperPlatformSecLibSample / Ia32 / SecEntry.S

#------------------------------------------------------------------------------\r
#\r
# Copyright (c) 2014, Intel Corporation. All rights reserved.<BR>\r
# This program and the accompanying materials\r
# are licensed and made available under the terms and conditions of the BSD License\r
# which accompanies this distribution.  The full text of the license may be found at\r
# http://opensource.org/licenses/bsd-license.php.\r
#\r
# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
#\r
# Module Name:\r
#\r
#  SecEntry.S\r
#\r
# Abstract:\r
#\r
#  This is the code that goes from real-mode to protected mode.\r
#  It consumes the reset vector, calls TempRamInit API from FSP binary.\r
#\r
#------------------------------------------------------------------------------\r
\r
#include "Fsp.h"\r
\r
ASM_GLOBAL    ASM_PFX(_gPcd_FixedAtBuild_PcdFsptBaseAddress)\r
\r
ASM_GLOBAL ASM_PFX(_TEXT_REALMODE)\r
ASM_PFX(_TEXT_REALMODE):\r
#----------------------------------------------------------------------------\r
#\r
# Procedure:    _ModuleEntryPoint\r
#\r
# Input:        None\r
#\r
# Output:       None\r
#\r
# Destroys:     Assume all registers\r
#\r
# Description:\r
#\r
#   Transition to non-paged flat-model protected mode from a\r
#   hard-coded GDT that provides exactly two descriptors.\r
#   This is a bare bones transition to protected mode only\r
#   used for a while in PEI and possibly DXE.\r
#\r
#   After enabling protected mode, a far jump is executed to\r
#   transfer to PEI using the newly loaded GDT.\r
#\r
# Return:       None\r
#\r
#  MMX Usage:\r
#              MM0 = BIST State\r
#              MM5 = Save time-stamp counter value high32bit\r
#              MM6 = Save time-stamp counter value low32bit.\r
#\r
#----------------------------------------------------------------------------\r
\r
.align 4\r
ASM_GLOBAL ASM_PFX(_ModuleEntryPoint)\r
ASM_PFX(_ModuleEntryPoint):\r
  fninit                                # clear any pending Floating point exceptions\r
  #\r
  # Store the BIST value in mm0\r
  #\r
  movd    %eax, %mm0\r
\r
  #\r
  # Save time-stamp counter value\r
  # rdtsc load 64bit time-stamp counter to EDX:EAX\r
  #\r
  rdtsc\r
  movd    %edx, %mm5\r
  movd    %ecx, %mm6\r
\r
  #\r
  # Load the GDT table in GdtDesc\r
  #\r
  movl    $GdtDesc, %esi\r
  .byte   0x66\r
  lgdt    %cs:(%si)\r
\r
  #\r
  # Transition to 16 bit protected mode\r
  #\r
  movl    %cr0, %eax                 # Get control register 0\r
  orl     $0x00000003, %eax          # Set PE bit (bit #0) & MP bit (bit #1)\r
  movl    %eax, %cr0                 # Activate protected mode\r
\r
  movl    %cr4, %eax                 # Get control register 4\r
  orl     $0x00000600, %eax          # Set OSFXSR bit (bit #9) & OSXMMEXCPT bit (bit #10)\r
  movl    %eax, %cr4\r
\r
  #\r
  # Now we're in 16 bit protected mode\r
  # Set up the selectors for 32 bit protected mode entry\r
  #\r
  movw    SYS_DATA_SEL, %ax\r
  movw    %ax, %ds\r
  movw    %ax, %es\r
  movw    %ax, %fs\r
  movw    %ax, %gs\r
  movw    %ax, %ss\r
\r
  #\r
  # Transition to Flat 32 bit protected mode\r
  # The jump to a far pointer causes the transition to 32 bit mode\r
  #\r
  movl    ASM_PFX(ProtectedModeEntryLinearAddress), %esi\r
  jmp     *%cs:(%si)\r
\r
ASM_GLOBAL ASM_PFX(_TEXT_PROTECTED_MODE)\r
ASM_PFX(_TEXT_PROTECTED_MODE):\r
\r
#----------------------------------------------------------------------------\r
#\r
# Procedure:    ProtectedModeEntryPoint\r
#\r
# Input:        None\r
#\r
# Output:       None\r
#\r
# Destroys:     Assume all registers\r
#\r
# Description:\r
#\r
# This function handles:\r
#   Call two basic APIs from FSP binary\r
#   Initializes stack with some early data (BIST, PEI entry, etc)\r
#\r
# Return:       None\r
#\r
#----------------------------------------------------------------------------\r
\r
.align 4\r
ASM_GLOBAL ASM_PFX(ProtectedModeEntryPoint)\r
ASM_PFX(ProtectedModeEntryPoint):\r
\r
  # Find the fsp info header\r
  movl ASM_PFX(_gPcd_FixedAtBuild_PcdFsptBaseAddress), %edi\r
\r
  movl FVH_SIGINATURE_OFFSET(%edi), %eax\r
  cmp  $FVH_SIGINATURE_VALID_VALUE, %eax\r
  jnz  FspHeaderNotFound\r
\r
  xorl %eax, %eax\r
  movw FVH_EXTHEADER_OFFSET_OFFSET(%edi), %ax\r
  cmp  %ax, 0\r
  jnz  FspFvExtHeaderExist\r
\r
  xorl %eax, %eax\r
  movw FVH_HEADER_LENGTH_OFFSET(%edi), %ax   # Bypass Fv Header\r
  addl %eax, %edi\r
  jmp  FspCheckFfsHeader\r
\r
FspFvExtHeaderExist:\r
  addl %eax, %edi\r
  movl FVH_EXTHEADER_SIZE_OFFSET(%edi), %eax  # Bypass Ext Fv Header\r
  addl %eax, %edi\r
\r
  # Round up to 8 byte alignment\r
  movl %edi, %eax\r
  andb $0x07, %al\r
  jz FspCheckFfsHeader\r
\r
  and  $0xFFFFFFF8, %edi\r
  add  $0x08, %edi\r
\r
FspCheckFfsHeader:\r
  # Check the ffs guid\r
  movl (%edi), %eax\r
  cmp  $FSP_HEADER_GUID_DWORD1, %eax\r
  jnz  FspHeaderNotFound\r
\r
  movl 0x4(%edi), %eax\r
  cmp  $FSP_HEADER_GUID_DWORD2, %eax\r
  jnz  FspHeaderNotFound\r
\r
  movl 0x08(%edi), %eax\r
  cmp  $FSP_HEADER_GUID_DWORD3, %eax\r
  jnz  FspHeaderNotFound\r
\r
  movl 0x0c(%edi), %eax\r
  cmp  $FSP_HEADER_GUID_DWORD4, %eax\r
  jnz  FspHeaderNotFound\r
\r
  add  $FFS_HEADER_SIZE_VALUE, %edi        # Bypass the ffs header\r
\r
  # Check the section type as raw section\r
  movb SECTION_HEADER_TYPE_OFFSET(%edi), %al\r
  cmp  $0x19, %al\r
  jnz  FspHeaderNotFound\r
\r
  addl $RAW_SECTION_HEADER_SIZE_VALUE, %edi  # Bypass the section header\r
  jmp  FspHeaderFound\r
\r
FspHeaderNotFound:\r
  jmp  .\r
\r
FspHeaderFound:\r
  # Get the fsp TempRamInit Api address\r
  movl FSP_HEADER_IMAGEBASE_OFFSET(%edi), %eax\r
  addl FSP_HEADER_TEMPRAMINIT_OFFSET(%edi), %eax\r
\r
  # Setup the hardcode stack\r
  movl $TempRamInitStack, %esp\r
\r
  # Call the fsp TempRamInit Api\r
  jmp  *%eax\r
\r
TempRamInitDone:\r
  cmp  $0x8000000E, %eax   #Check if EFI_NOT_FOUND returned. Error code for Microcode Update not found.\r
  je   CallSecFspInit      #If microcode not found, don't hang, but continue.\r
\r
  cmp  $0x0, %eax\r
  jnz  FspApiFailed\r
\r
  #   ECX: start of range\r
  #   EDX: end of range\r
CallSecFspInit:\r
  xorl    %eax, %eax\r
  movl    %edx, %esp\r
\r
  # Align the stack at DWORD\r
  addl  $3, %esp\r
  andl  $0xFFFFFFFC, %esp\r
\r
  pushl   %edx\r
  pushl   %ecx\r
  pushl   %eax # zero - no hob list yet\r
  call ASM_PFX(CallPeiCoreEntryPoint)\r
\r
FspApiFailed:\r
  jmp .\r
\r
.align 0x10\r
TempRamInitStack:\r
    .long  TempRamInitDone\r
    .long  ASM_PFX(FsptUpdDataPtr)\r
\r
#\r
# ROM-based Global-Descriptor Table for the Tiano PEI Phase\r
#\r
.align 16\r
\r
#\r
# GDT[0]: 0x00: Null entry, never used.\r
#\r
.equ NULL_SEL,             . - GDT_BASE    # Selector [0]\r
GDT_BASE:\r
BootGdtTable:       .long  0\r
                    .long  0\r
#\r
# Linear data segment descriptor\r
#\r
.equ LINEAR_SEL,           . - GDT_BASE    # Selector [0x8]\r
    .word  0xFFFF                          # limit 0xFFFFF\r
    .word  0                               # base 0\r
    .byte  0\r
    .byte  0x92                            # present, ring 0, data, expand-up, writable\r
    .byte  0xCF                            # page-granular, 32-bit\r
    .byte  0\r
#\r
# Linear code segment descriptor\r
#\r
.equ LINEAR_CODE_SEL,      . - GDT_BASE    # Selector [0x10]\r
    .word  0xFFFF                          # limit 0xFFFFF\r
    .word  0                               # base 0\r
    .byte  0\r
    .byte  0x9B                            # present, ring 0, data, expand-up, not-writable\r
    .byte  0xCF                            # page-granular, 32-bit\r
    .byte  0\r
#\r
# System data segment descriptor\r
#\r
.equ SYS_DATA_SEL,         . - GDT_BASE    # Selector [0x18]\r
    .word  0xFFFF                          # limit 0xFFFFF\r
    .word  0                               # base 0\r
    .byte  0\r
    .byte  0x93                            # present, ring 0, data, expand-up, not-writable\r
    .byte  0xCF                            # page-granular, 32-bit\r
    .byte  0\r
\r
#\r
# System code segment descriptor\r
#\r
.equ SYS_CODE_SEL,         . - GDT_BASE    # Selector [0x20]\r
    .word  0xFFFF                          # limit 0xFFFFF\r
    .word  0                               # base 0\r
    .byte  0\r
    .byte  0x9A                            # present, ring 0, data, expand-up, writable\r
    .byte  0xCF                            # page-granular, 32-bit\r
    .byte  0\r
#\r
# Spare segment descriptor\r
#\r
.equ SYS16_CODE_SEL,       . - GDT_BASE    # Selector [0x28]\r
    .word  0xFFFF                          # limit 0xFFFFF\r
    .word  0                               # base 0\r
    .byte  0x0E                            # Changed from F000 to E000.\r
    .byte  0x9B                            # present, ring 0, code, expand-up, writable\r
    .byte  0x00                            # byte-granular, 16-bit\r
    .byte  0\r
#\r
# Spare segment descriptor\r
#\r
.equ SYS16_DATA_SEL,       . - GDT_BASE    # Selector [0x30]\r
    .word  0xFFFF                          # limit 0xFFFF\r
    .word  0                               # base 0\r
    .byte  0\r
    .byte  0x93                            # present, ring 0, data, expand-up, not-writable\r
    .byte  0x00                            # byte-granular, 16-bit\r
    .byte  0\r
\r
#\r
# Spare segment descriptor\r
#\r
.equ SPARE5_SEL,           . - GDT_BASE    # Selector [0x38]\r
    .word  0                               # limit 0\r
    .word  0                               # base 0\r
    .byte  0\r
    .byte  0                               # present, ring 0, data, expand-up, writable\r
    .byte  0                               # page-granular, 32-bit\r
    .byte  0\r
.equ GDT_SIZE,             . - BootGdtTable    # Size, in bytes\r
\r
#\r
# GDT Descriptor\r
#\r
GdtDesc:                                # GDT descriptor\r
    .word  GDT_SIZE - 1                    # GDT limit\r
    .long  BootGdtTable                    # GDT base address\r
\r
ASM_PFX(ProtectedModeEntryLinearAddress):\r
ProtectedModeEntryLinearOffset:\r
  .long      ASM_PFX(ProtectedModeEntryPoint)  # Offset of our 32 bit code\r
  .word      LINEAR_CODE_SEL\r
Commit	Line	Data
cf1d4549 JY	1	#------------------------------------------------------------------------------\r
	2	#\r
	3	# Copyright (c) 2014, Intel Corporation. All rights reserved.<BR>\r
	4	# This program and the accompanying materials\r
	5	# are licensed and made available under the terms and conditions of the BSD License\r
	6	# which accompanies this distribution. The full text of the license may be found at\r
	7	# http://opensource.org/licenses/bsd-license.php.\r
	8	#\r
	9	# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,\r
	10	# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.\r
	11	#\r
	12	# Module Name:\r
	13	#\r
	14	# SecEntry.S\r
	15	#\r
	16	# Abstract:\r
	17	#\r
	18	# This is the code that goes from real-mode to protected mode.\r
	19	# It consumes the reset vector, calls TempRamInit API from FSP binary.\r
	20	#\r
	21	#------------------------------------------------------------------------------\r
	22	\r
	23	#include "Fsp.h"\r
	24	\r
	25	ASM_GLOBAL ASM_PFX(_gPcd_FixedAtBuild_PcdFsptBaseAddress)\r
	26	\r
	27	ASM_GLOBAL ASM_PFX(_TEXT_REALMODE)\r
	28	ASM_PFX(_TEXT_REALMODE):\r
	29	#----------------------------------------------------------------------------\r
	30	#\r
	31	# Procedure: _ModuleEntryPoint\r
	32	#\r
	33	# Input: None\r
	34	#\r
	35	# Output: None\r
	36	#\r
	37	# Destroys: Assume all registers\r
	38	#\r
	39	# Description:\r
	40	#\r
	41	# Transition to non-paged flat-model protected mode from a\r
	42	# hard-coded GDT that provides exactly two descriptors.\r
	43	# This is a bare bones transition to protected mode only\r
	44	# used for a while in PEI and possibly DXE.\r
	45	#\r
	46	# After enabling protected mode, a far jump is executed to\r
	47	# transfer to PEI using the newly loaded GDT.\r
	48	#\r
	49	# Return: None\r
	50	#\r
	51	# MMX Usage:\r
	52	# MM0 = BIST State\r
	53	# MM5 = Save time-stamp counter value high32bit\r
	54	# MM6 = Save time-stamp counter value low32bit.\r
	55	#\r
	56	#----------------------------------------------------------------------------\r
	57	\r
	58	.align 4\r
	59	ASM_GLOBAL ASM_PFX(_ModuleEntryPoint)\r
	60	ASM_PFX(_ModuleEntryPoint):\r
	61	fninit # clear any pending Floating point exceptions\r
	62	#\r
	63	# Store the BIST value in mm0\r
	64	#\r
65	movd %eax, %mm0\r
66	\r
67	#\r
68	# Save time-stamp counter value\r
69	# rdtsc load 64bit time-stamp counter to EDX:EAX\r
70	#\r
71	rdtsc\r
72	movd %edx, %mm5\r
73	movd %ecx, %mm6\r
74	\r
75	#\r
76	# Load the GDT table in GdtDesc\r
77	#\r
78	movl $GdtDesc, %esi\r
79	.byte 0x66\r
80	lgdt %cs:(%si)\r
81	\r
82	#\r
83	# Transition to 16 bit protected mode\r
84	#\r
85	movl %cr0, %eax # Get control register 0\r
86	orl $0x00000003, %eax # Set PE bit (bit #0) & MP bit (bit #1)\r
87	movl %eax, %cr0 # Activate protected mode\r
88	\r
89	movl %cr4, %eax # Get control register 4\r
90	orl $0x00000600, %eax # Set OSFXSR bit (bit #9) & OSXMMEXCPT bit (bit #10)\r
91	movl %eax, %cr4\r
92	\r
93	#\r
94	# Now we're in 16 bit protected mode\r
95	# Set up the selectors for 32 bit protected mode entry\r
96	#\r
97	movw SYS_DATA_SEL, %ax\r
98	movw %ax, %ds\r
99	movw %ax, %es\r
100	movw %ax, %fs\r
101	movw %ax, %gs\r
102	movw %ax, %ss\r
103	\r
104	#\r
105	# Transition to Flat 32 bit protected mode\r
106	# The jump to a far pointer causes the transition to 32 bit mode\r
107	#\r
108	movl ASM_PFX(ProtectedModeEntryLinearAddress), %esi\r
109	jmp *%cs:(%si)\r
110	\r
111	ASM_GLOBAL ASM_PFX(_TEXT_PROTECTED_MODE)\r
112	ASM_PFX(_TEXT_PROTECTED_MODE):\r
113	\r
114	#----------------------------------------------------------------------------\r
115	#\r
116	# Procedure: ProtectedModeEntryPoint\r
117	#\r
118	# Input: None\r
119	#\r
120	# Output: None\r
121	#\r
122	# Destroys: Assume all registers\r
123	#\r
124	# Description:\r
125	#\r
126	# This function handles:\r
127	# Call two basic APIs from FSP binary\r
128	# Initializes stack with some early data (BIST, PEI entry, etc)\r
129	#\r
130	# Return: None\r
131	#\r
132	#----------------------------------------------------------------------------\r
133	\r
134	.align 4\r
135	ASM_GLOBAL ASM_PFX(ProtectedModeEntryPoint)\r
136	ASM_PFX(ProtectedModeEntryPoint):\r
137	\r
138	# Find the fsp info header\r
139	movl ASM_PFX(_gPcd_FixedAtBuild_PcdFsptBaseAddress), %edi\r
140	\r
141	movl FVH_SIGINATURE_OFFSET(%edi), %eax\r
142	cmp $FVH_SIGINATURE_VALID_VALUE, %eax\r
143	jnz FspHeaderNotFound\r
144	\r
145	xorl %eax, %eax\r
146	movw FVH_EXTHEADER_OFFSET_OFFSET(%edi), %ax\r
147	cmp %ax, 0\r
148	jnz FspFvExtHeaderExist\r
149	\r
150	xorl %eax, %eax\r
151	movw FVH_HEADER_LENGTH_OFFSET(%edi), %ax # Bypass Fv Header\r
152	addl %eax, %edi\r
153	jmp FspCheckFfsHeader\r
154	\r
155	FspFvExtHeaderExist:\r
156	addl %eax, %edi\r
157	movl FVH_EXTHEADER_SIZE_OFFSET(%edi), %eax # Bypass Ext Fv Header\r
158	addl %eax, %edi\r
159	\r
160	# Round up to 8 byte alignment\r
161	movl %edi, %eax\r
162	andb $0x07, %al\r
163	jz FspCheckFfsHeader\r
164	\r
165	and $0xFFFFFFF8, %edi\r
166	add $0x08, %edi\r
167	\r
168	FspCheckFfsHeader:\r
169	# Check the ffs guid\r
170	movl (%edi), %eax\r
171	cmp $FSP_HEADER_GUID_DWORD1, %eax\r
172	jnz FspHeaderNotFound\r
173	\r
174	movl 0x4(%edi), %eax\r
175	cmp $FSP_HEADER_GUID_DWORD2, %eax\r
176	jnz FspHeaderNotFound\r
177	\r
178	movl 0x08(%edi), %eax\r
179	cmp $FSP_HEADER_GUID_DWORD3, %eax\r
180	jnz FspHeaderNotFound\r
181	\r
182	movl 0x0c(%edi), %eax\r
183	cmp $FSP_HEADER_GUID_DWORD4, %eax\r
184	jnz FspHeaderNotFound\r
185	\r
186	add $FFS_HEADER_SIZE_VALUE, %edi # Bypass the ffs header\r
187	\r
188	# Check the section type as raw section\r
189	movb SECTION_HEADER_TYPE_OFFSET(%edi), %al\r
190	cmp $0x19, %al\r
191	jnz FspHeaderNotFound\r
192	\r
193	addl $RAW_SECTION_HEADER_SIZE_VALUE, %edi # Bypass the section header\r
194	jmp FspHeaderFound\r
195	\r
196	FspHeaderNotFound:\r
197	jmp .\r
198	\r
199	FspHeaderFound:\r
200	# Get the fsp TempRamInit Api address\r
201	movl FSP_HEADER_IMAGEBASE_OFFSET(%edi), %eax\r
202	addl FSP_HEADER_TEMPRAMINIT_OFFSET(%edi), %eax\r
203	\r
204	# Setup the hardcode stack\r
205	movl $TempRamInitStack, %esp\r
206	\r
207	# Call the fsp TempRamInit Api\r
208	jmp *%eax\r
209	\r
210	TempRamInitDone:\r
211	cmp $0x8000000E, %eax #Check if EFI_NOT_FOUND returned. Error code for Microcode Update not found.\r
212	je CallSecFspInit #If microcode not found, don't hang, but continue.\r
213	\r
214	cmp $0x0, %eax\r
215	jnz FspApiFailed\r
216	\r
217	# ECX: start of range\r
218	# EDX: end of range\r
219	CallSecFspInit:\r
220	xorl %eax, %eax\r
221	movl %edx, %esp\r
222	\r
223	# Align the stack at DWORD\r
224	addl $3, %esp\r
225	andl $0xFFFFFFFC, %esp\r
226	\r
227	pushl %edx\r
228	pushl %ecx\r
229	pushl %eax # zero - no hob list yet\r
230	call ASM_PFX(CallPeiCoreEntryPoint)\r
231	\r
232	FspApiFailed:\r
233	jmp .\r
234	\r
235	.align 0x10\r
236	TempRamInitStack:\r
237	.long TempRamInitDone\r
238	.long ASM_PFX(FsptUpdDataPtr)\r
239	\r
240	#\r
241	# ROM-based Global-Descriptor Table for the Tiano PEI Phase\r
242	#\r
243	.align 16\r
244	\r
245	#\r
246	# GDT[0]: 0x00: Null entry, never used.\r
247	#\r
248	.equ NULL_SEL, . - GDT_BASE # Selector [0]\r
249	GDT_BASE:\r
250	BootGdtTable: .long 0\r
251	.long 0\r
252	#\r
253	# Linear data segment descriptor\r
254	#\r
255	.equ LINEAR_SEL, . - GDT_BASE # Selector [0x8]\r
256	.word 0xFFFF # limit 0xFFFFF\r
257	.word 0 # base 0\r
258	.byte 0\r
259	.byte 0x92 # present, ring 0, data, expand-up, writable\r
260	.byte 0xCF # page-granular, 32-bit\r
261	.byte 0\r
262	#\r
263	# Linear code segment descriptor\r
264	#\r
265	.equ LINEAR_CODE_SEL, . - GDT_BASE # Selector [0x10]\r
266	.word 0xFFFF # limit 0xFFFFF\r
267	.word 0 # base 0\r
268	.byte 0\r
269	.byte 0x9B # present, ring 0, data, expand-up, not-writable\r
270	.byte 0xCF # page-granular, 32-bit\r
271	.byte 0\r
272	#\r
273	# System data segment descriptor\r
274	#\r
275	.equ SYS_DATA_SEL, . - GDT_BASE # Selector [0x18]\r
276	.word 0xFFFF # limit 0xFFFFF\r
277	.word 0 # base 0\r
278	.byte 0\r
279	.byte 0x93 # present, ring 0, data, expand-up, not-writable\r
280	.byte 0xCF # page-granular, 32-bit\r
281	.byte 0\r
282	\r
283	#\r
284	# System code segment descriptor\r
285	#\r
286	.equ SYS_CODE_SEL, . - GDT_BASE # Selector [0x20]\r
287	.word 0xFFFF # limit 0xFFFFF\r
288	.word 0 # base 0\r
289	.byte 0\r
290	.byte 0x9A # present, ring 0, data, expand-up, writable\r
291	.byte 0xCF # page-granular, 32-bit\r
292	.byte 0\r
293	#\r
294	# Spare segment descriptor\r
295	#\r
296	.equ SYS16_CODE_SEL, . - GDT_BASE # Selector [0x28]\r
297	.word 0xFFFF # limit 0xFFFFF\r
298	.word 0 # base 0\r
299	.byte 0x0E # Changed from F000 to E000.\r
300	.byte 0x9B # present, ring 0, code, expand-up, writable\r
301	.byte 0x00 # byte-granular, 16-bit\r
302	.byte 0\r
303	#\r
304	# Spare segment descriptor\r
305	#\r
306	.equ SYS16_DATA_SEL, . - GDT_BASE # Selector [0x30]\r
307	.word 0xFFFF # limit 0xFFFF\r
308	.word 0 # base 0\r
309	.byte 0\r
310	.byte 0x93 # present, ring 0, data, expand-up, not-writable\r
311	.byte 0x00 # byte-granular, 16-bit\r
312	.byte 0\r
313	\r
314	#\r
315	# Spare segment descriptor\r
316	#\r
317	.equ SPARE5_SEL, . - GDT_BASE # Selector [0x38]\r
318	.word 0 # limit 0\r
319	.word 0 # base 0\r
320	.byte 0\r
321	.byte 0 # present, ring 0, data, expand-up, writable\r
322	.byte 0 # page-granular, 32-bit\r
323	.byte 0\r
324	.equ GDT_SIZE, . - BootGdtTable # Size, in bytes\r
325	\r
326	#\r
327	# GDT Descriptor\r
328	#\r
329	GdtDesc: # GDT descriptor\r
330	.word GDT_SIZE - 1 # GDT limit\r
331	.long BootGdtTable # GDT base address\r
332	\r
333	ASM_PFX(ProtectedModeEntryLinearAddress):\r
334	ProtectedModeEntryLinearOffset:\r
335	.long ASM_PFX(ProtectedModeEntryPoint) # Offset of our 32 bit code\r
336	.word LINEAR_CODE_SEL\r