4 * Copyright (C) 1991, 1992 Linus Torvalds
6 * Based on bootsect.S and setup.S
7 * modified by more people than can be counted
9 * Rewritten as a common file by H. Peter Anvin (Apr 2007)
11 * BIG FAT NOTE: We're in real mode using 64k segments. Therefore segment
12 * addresses must be multiplied by 16 to obtain their respective linear
13 * addresses. To avoid confusion, linear addresses are written using leading
14 * hex while segment addresses are written as segment:offset.
18 #include <asm/segment.h>
19 #include <generated/utsrelease.h>
22 #include <asm/page_types.h>
23 #include <asm/setup.h>
28 BOOTSEG = 0x07C0 /* original address of boot-sector */
29 SYSSEG = 0x1000 /* historical load address >> 4 */
32 #define SVGA_MODE ASK_VGA
44 .section ".bstext", "ax"
46 .global bootsect_start
48 #ifdef CONFIG_EFI_STUB
54 # Normalize the start address
55 ljmp $BOOTSEG, $start2
66 movw $bugger_off_msg, %si
78 # Allow the user to press a key, then reboot
83 # int 0x19 should never return. In case it does anyway,
84 # invoke the BIOS reset code...
87 #ifdef CONFIG_EFI_STUB
90 # Offset to the PE header.
93 #endif /* CONFIG_EFI_STUB */
95 .section ".bsdata", "a"
97 .ascii "Direct booting from floppy is no longer supported.\r\n"
98 .ascii "Please use a boot loader program instead.\r\n"
100 .ascii "Remove disk and press any key to reboot . . .\r\n"
103 #ifdef CONFIG_EFI_STUB
112 .word 0x8664 # x86-64
114 .word 2 # nr_sections
115 .long 0 # TimeDateStamp
116 .long 0 # PointerToSymbolTable
117 .long 1 # NumberOfSymbols
118 .word section_table - optional_header # SizeOfOptionalHeader
120 .word 0x306 # Characteristics.
121 # IMAGE_FILE_32BIT_MACHINE |
122 # IMAGE_FILE_DEBUG_STRIPPED |
123 # IMAGE_FILE_EXECUTABLE_IMAGE |
124 # IMAGE_FILE_LINE_NUMS_STRIPPED
126 .word 0x206 # Characteristics
127 # IMAGE_FILE_DEBUG_STRIPPED |
128 # IMAGE_FILE_EXECUTABLE_IMAGE |
129 # IMAGE_FILE_LINE_NUMS_STRIPPED
134 .word 0x10b # PE32 format
136 .word 0x20b # PE32+ format
138 .byte 0x02 # MajorLinkerVersion
139 .byte 0x14 # MinorLinkerVersion
141 # Filled in by build.c
144 .long 0 # SizeOfInitializedData
145 .long 0 # SizeOfUninitializedData
147 # Filled in by build.c
148 .long 0x0000 # AddressOfEntryPoint
150 .long 0x0200 # BaseOfCode
161 .long 0x1000 # SectionAlignment
162 .long 0x200 # FileAlignment
163 .word 0 # MajorOperatingSystemVersion
164 .word 0 # MinorOperatingSystemVersion
165 .word 0 # MajorImageVersion
166 .word 0 # MinorImageVersion
167 .word 0 # MajorSubsystemVersion
168 .word 0 # MinorSubsystemVersion
169 .long 0 # Win32VersionValue
172 # The size of the bzImage is written in tools/build.c
174 .long 0 # SizeOfImage
176 .long 0x200 # SizeOfHeaders
178 .word 0xa # Subsystem (EFI application)
179 .word 0 # DllCharacteristics
181 .long 0 # SizeOfStackReserve
182 .long 0 # SizeOfStackCommit
183 .long 0 # SizeOfHeapReserve
184 .long 0 # SizeOfHeapCommit
186 .quad 0 # SizeOfStackReserve
187 .quad 0 # SizeOfStackCommit
188 .quad 0 # SizeOfHeapReserve
189 .quad 0 # SizeOfHeapCommit
191 .long 0 # LoaderFlags
192 .long 0x6 # NumberOfRvaAndSizes
194 .quad 0 # ExportTable
195 .quad 0 # ImportTable
196 .quad 0 # ResourceTable
197 .quad 0 # ExceptionTable
198 .quad 0 # CertificationTable
199 .quad 0 # BaseRelocationTable
208 .long 0x0 # startup_{32,64}
209 .long 0 # Size of initialized data
211 .long 0x0 # startup_{32,64}
212 .long 0 # PointerToRelocations
213 .long 0 # PointerToLineNumbers
214 .word 0 # NumberOfRelocations
215 .word 0 # NumberOfLineNumbers
216 .long 0x60500020 # Characteristics (section flags)
219 # The EFI application loader requires a relocation section
220 # because EFI applications must be relocatable. But since
221 # we don't need the loader to fixup any relocs for us, we
222 # just create an empty (zero-length) .reloc section header.
229 .long 0 # SizeOfRawData
230 .long 0 # PointerToRawData
231 .long 0 # PointerToRelocations
232 .long 0 # PointerToLineNumbers
233 .word 0 # NumberOfRelocations
234 .word 0 # NumberOfLineNumbers
235 .long 0x42100040 # Characteristics (section flags)
236 #endif /* CONFIG_EFI_STUB */
238 # Kernel attributes; used by setup. This is part 1 of the
239 # header, from the old boot sector.
241 .section ".header", "a"
244 setup_sects: .byte 0 /* Filled in by build.c */
245 root_flags: .word ROOT_RDONLY
246 syssize: .long 0 /* Filled in by build.c */
247 ram_size: .word 0 /* Obsolete */
248 vid_mode: .word SVGA_MODE
249 root_dev: .word 0 /* Filled in by build.c */
250 boot_flag: .word 0xAA55
252 # offset 512, entry point
256 # Explicitly enter this as bytes, or the assembler
257 # tries to generate a 3-byte jump here, which causes
258 # everything else to push off to the wrong offset.
259 .byte 0xeb # short (2-byte) jump
260 .byte start_of_setup-1f
263 # Part 2 of the header, from the old setup.S
265 .ascii "HdrS" # header signature
266 .word 0x020a # header version number (>= 0x0105)
267 # or else old loadlin-1.5 will fail)
268 .globl realmode_swtch
269 realmode_swtch: .word 0, 0 # default_switch, SETUPSEG
270 start_sys_seg: .word SYSSEG # obsolete and meaningless, but just
271 # in case something decided to "use" it
272 .word kernel_version-512 # pointing to kernel version string
273 # above section of header is compatible
274 # with loadlin-1.5 (header v1.5). Don't
277 type_of_loader: .byte 0 # 0 means ancient bootloader, newer
278 # bootloaders know to change this.
279 # See Documentation/x86/boot.txt for
282 # flags, unused bits must be zero (RFU) bit within loadflags
284 LOADED_HIGH = 1 # If set, the kernel is loaded high
285 CAN_USE_HEAP = 0x80 # If set, the loader also has set
286 # heap_end_ptr to tell how much
287 # space behind setup.S can be used for
289 # Only the loader knows what is free
292 setup_move_size: .word 0x8000 # size to move, when setup is not
293 # loaded at 0x90000. We will move setup
294 # to 0x90000 then just before jumping
295 # into the kernel. However, only the
296 # loader knows how much data behind
297 # us also needs to be loaded.
299 code32_start: # here loaders can put a different
300 # start address for 32-bit code.
301 .long 0x100000 # 0x100000 = default for big kernel
303 ramdisk_image: .long 0 # address of loaded ramdisk image
304 # Here the loader puts the 32-bit
305 # address where it loaded the image.
306 # This only will be read by the kernel.
308 ramdisk_size: .long 0 # its size in bytes
313 heap_end_ptr: .word _end+STACK_SIZE-512
314 # (Header version 0x0201 or later)
315 # space from here (exclusive) down to
316 # end of setup code can be used by setup
317 # for local heap purposes.
320 .byte 0 # Extended boot loader version
322 .byte 0 # Extended boot loader type
324 cmd_line_ptr: .long 0 # (Header version 0x0202 or later)
325 # If nonzero, a 32-bit pointer
326 # to the kernel command line.
327 # The command line should be
328 # located between the start of
329 # setup and the end of low
330 # memory (0xa0000), or it may
331 # get overwritten before it
332 # gets read. If this field is
333 # used, there is no longer
334 # anything magical about the
335 # 0x90000 segment; the setup
336 # can be located anywhere in
337 # low memory 0x10000 or higher.
339 ramdisk_max: .long 0x7fffffff
340 # (Header version 0x0203 or later)
341 # The highest safe address for
342 # the contents of an initrd
343 # The current kernel allows up to 4 GB,
344 # but leave it at 2 GB to avoid
345 # possible bootloader bugs.
347 kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment
348 #required for protected mode
350 #ifdef CONFIG_RELOCATABLE
351 relocatable_kernel: .byte 1
353 relocatable_kernel: .byte 0
355 min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment
358 cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line,
359 #added with boot protocol
362 hardware_subarch: .long 0 # subarchitecture, added with 2.07
363 # default to 0 for normal x86 PC
365 hardware_subarch_data: .quad 0
367 payload_offset: .long ZO_input_data
368 payload_length: .long ZO_z_input_len
370 setup_data: .quad 0 # 64-bit physical pointer to
371 # single linked list of
374 pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr
376 #define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_extract_offset)
377 #define VO_INIT_SIZE (VO__end - VO__text)
378 #if ZO_INIT_SIZE > VO_INIT_SIZE
379 #define INIT_SIZE ZO_INIT_SIZE
381 #define INIT_SIZE VO_INIT_SIZE
383 init_size: .long INIT_SIZE # kernel initialization size
385 # End of setup header #####################################################
387 .section ".entrytext", "ax"
389 #ifdef SAFE_RESET_DISK_CONTROLLER
390 # Reset the disk controller.
391 movw $0x0000, %ax # Reset disk controller
392 movb $0x80, %dl # All disks
401 # Apparently some ancient versions of LILO invoked the kernel with %ss != %ds,
402 # which happened to work by accident for the old code. Recalculate the stack
403 # pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the
404 # stack behind its own code, so we can't blindly put it directly past the heap.
407 cmpw %ax, %dx # %ds == %ss?
409 je 2f # -> assume %sp is reasonably set
411 # Invalid %ss, make up a new stack
413 testb $CAN_USE_HEAP, loadflags
415 movw heap_end_ptr, %dx
416 1: addw $STACK_SIZE, %dx
418 xorw %dx, %dx # Prevent wraparound
420 2: # Now %dx should point to the end of our stack space
421 andw $~3, %dx # dword align (might as well...)
423 movw $0xfffc, %dx # Make sure we're not zero
425 movzwl %dx, %esp # Clear upper half of %esp
426 sti # Now we should have a working stack
428 # We will have entered with %cs = %ds+0x20, normalize %cs so
429 # it is on par with the other segments.
435 # Check signature at end of setup
436 cmpl $0x5a5aaa55, setup_sig
440 movw $__bss_start, %di
447 # Jump to C code (should not return)
450 # Setup corrupt somehow...
452 movl $setup_corrupt, %eax
464 .section ".initdata", "a"
467 .string "No setup signature found...\n"