Commit | Line | Data |
---|---|---|
62607313 PA |
1 | /* |
2 | * header.S | |
3 | * | |
4 | * Copyright (C) 1991, 1992 Linus Torvalds | |
5 | * | |
6 | * Based on bootsect.S and setup.S | |
7 | * modified by more people than can be counted | |
8 | * | |
9 | * Rewritten as a common file by H. Peter Anvin (Apr 2007) | |
10 | * | |
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. | |
15 | * | |
16 | */ | |
17 | ||
18 | #include <asm/segment.h> | |
273b281f | 19 | #include <generated/utsrelease.h> |
62607313 PA |
20 | #include <asm/boot.h> |
21 | #include <asm/e820.h> | |
0341c14d | 22 | #include <asm/page_types.h> |
62607313 | 23 | #include <asm/setup.h> |
09c205af | 24 | #include <asm/bootparam.h> |
62607313 | 25 | #include "boot.h" |
77d1a499 PA |
26 | #include "voffset.h" |
27 | #include "zoffset.h" | |
62607313 | 28 | |
62607313 | 29 | BOOTSEG = 0x07C0 /* original address of boot-sector */ |
5e47c478 | 30 | SYSSEG = 0x1000 /* historical load address >> 4 */ |
62607313 PA |
31 | |
32 | #ifndef SVGA_MODE | |
33 | #define SVGA_MODE ASK_VGA | |
34 | #endif | |
35 | ||
62607313 PA |
36 | #ifndef ROOT_RDONLY |
37 | #define ROOT_RDONLY 1 | |
38 | #endif | |
39 | ||
40 | .code16 | |
41 | .section ".bstext", "ax" | |
42 | ||
43 | .global bootsect_start | |
44 | bootsect_start: | |
291f3632 MF |
45 | #ifdef CONFIG_EFI_STUB |
46 | # "MZ", MS-DOS header | |
47 | .byte 0x4d | |
48 | .byte 0x5a | |
49 | #endif | |
62607313 PA |
50 | |
51 | # Normalize the start address | |
52 | ljmp $BOOTSEG, $start2 | |
53 | ||
54 | start2: | |
55 | movw %cs, %ax | |
56 | movw %ax, %ds | |
57 | movw %ax, %es | |
58 | movw %ax, %ss | |
59 | xorw %sp, %sp | |
60 | sti | |
61 | cld | |
62 | ||
63 | movw $bugger_off_msg, %si | |
64 | ||
65 | msg_loop: | |
66 | lodsb | |
67 | andb %al, %al | |
68 | jz bs_die | |
69 | movb $0xe, %ah | |
70 | movw $7, %bx | |
71 | int $0x10 | |
72 | jmp msg_loop | |
73 | ||
74 | bs_die: | |
75 | # Allow the user to press a key, then reboot | |
76 | xorw %ax, %ax | |
77 | int $0x16 | |
78 | int $0x19 | |
79 | ||
80 | # int 0x19 should never return. In case it does anyway, | |
81 | # invoke the BIOS reset code... | |
82 | ljmp $0xf000,$0xfff0 | |
83 | ||
291f3632 MF |
84 | #ifdef CONFIG_EFI_STUB |
85 | .org 0x3c | |
86 | # | |
87 | # Offset to the PE header. | |
88 | # | |
89 | .long pe_header | |
90 | #endif /* CONFIG_EFI_STUB */ | |
91 | ||
62607313 PA |
92 | .section ".bsdata", "a" |
93 | bugger_off_msg: | |
c7fb93ec | 94 | .ascii "Use a boot loader.\r\n" |
62607313 | 95 | .ascii "\n" |
c7fb93ec | 96 | .ascii "Remove disk and press any key to reboot...\r\n" |
62607313 PA |
97 | .byte 0 |
98 | ||
291f3632 MF |
99 | #ifdef CONFIG_EFI_STUB |
100 | pe_header: | |
101 | .ascii "PE" | |
102 | .word 0 | |
103 | ||
104 | coff_header: | |
105 | #ifdef CONFIG_X86_32 | |
106 | .word 0x14c # i386 | |
107 | #else | |
108 | .word 0x8664 # x86-64 | |
109 | #endif | |
c7fb93ec | 110 | .word 4 # nr_sections |
291f3632 MF |
111 | .long 0 # TimeDateStamp |
112 | .long 0 # PointerToSymbolTable | |
113 | .long 1 # NumberOfSymbols | |
114 | .word section_table - optional_header # SizeOfOptionalHeader | |
115 | #ifdef CONFIG_X86_32 | |
116 | .word 0x306 # Characteristics. | |
117 | # IMAGE_FILE_32BIT_MACHINE | | |
118 | # IMAGE_FILE_DEBUG_STRIPPED | | |
119 | # IMAGE_FILE_EXECUTABLE_IMAGE | | |
120 | # IMAGE_FILE_LINE_NUMS_STRIPPED | |
121 | #else | |
122 | .word 0x206 # Characteristics | |
123 | # IMAGE_FILE_DEBUG_STRIPPED | | |
124 | # IMAGE_FILE_EXECUTABLE_IMAGE | | |
125 | # IMAGE_FILE_LINE_NUMS_STRIPPED | |
126 | #endif | |
127 | ||
128 | optional_header: | |
129 | #ifdef CONFIG_X86_32 | |
130 | .word 0x10b # PE32 format | |
131 | #else | |
132 | .word 0x20b # PE32+ format | |
133 | #endif | |
134 | .byte 0x02 # MajorLinkerVersion | |
135 | .byte 0x14 # MinorLinkerVersion | |
136 | ||
137 | # Filled in by build.c | |
138 | .long 0 # SizeOfCode | |
139 | ||
140 | .long 0 # SizeOfInitializedData | |
141 | .long 0 # SizeOfUninitializedData | |
142 | ||
143 | # Filled in by build.c | |
144 | .long 0x0000 # AddressOfEntryPoint | |
145 | ||
e31be363 | 146 | .long 0x0200 # BaseOfCode |
291f3632 MF |
147 | #ifdef CONFIG_X86_32 |
148 | .long 0 # data | |
149 | #endif | |
150 | ||
151 | extra_header_fields: | |
152 | #ifdef CONFIG_X86_32 | |
153 | .long 0 # ImageBase | |
154 | #else | |
155 | .quad 0 # ImageBase | |
156 | #endif | |
fa5c3501 | 157 | .long 0x20 # SectionAlignment |
743628e8 | 158 | .long 0x20 # FileAlignment |
291f3632 MF |
159 | .word 0 # MajorOperatingSystemVersion |
160 | .word 0 # MinorOperatingSystemVersion | |
161 | .word 0 # MajorImageVersion | |
162 | .word 0 # MinorImageVersion | |
163 | .word 0 # MajorSubsystemVersion | |
164 | .word 0 # MinorSubsystemVersion | |
165 | .long 0 # Win32VersionValue | |
166 | ||
167 | # | |
168 | # The size of the bzImage is written in tools/build.c | |
169 | # | |
170 | .long 0 # SizeOfImage | |
171 | ||
172 | .long 0x200 # SizeOfHeaders | |
173 | .long 0 # CheckSum | |
174 | .word 0xa # Subsystem (EFI application) | |
175 | .word 0 # DllCharacteristics | |
176 | #ifdef CONFIG_X86_32 | |
177 | .long 0 # SizeOfStackReserve | |
178 | .long 0 # SizeOfStackCommit | |
179 | .long 0 # SizeOfHeapReserve | |
180 | .long 0 # SizeOfHeapCommit | |
181 | #else | |
182 | .quad 0 # SizeOfStackReserve | |
183 | .quad 0 # SizeOfStackCommit | |
184 | .quad 0 # SizeOfHeapReserve | |
185 | .quad 0 # SizeOfHeapCommit | |
186 | #endif | |
187 | .long 0 # LoaderFlags | |
e47bb0bd | 188 | .long 0x6 # NumberOfRvaAndSizes |
291f3632 MF |
189 | |
190 | .quad 0 # ExportTable | |
191 | .quad 0 # ImportTable | |
192 | .quad 0 # ResourceTable | |
193 | .quad 0 # ExceptionTable | |
194 | .quad 0 # CertificationTable | |
195 | .quad 0 # BaseRelocationTable | |
196 | ||
197 | # Section table | |
198 | section_table: | |
743628e8 JJ |
199 | # |
200 | # The offset & size fields are filled in by build.c. | |
201 | # | |
202 | .ascii ".setup" | |
291f3632 MF |
203 | .byte 0 |
204 | .byte 0 | |
205 | .long 0 | |
206 | .long 0x0 # startup_{32,64} | |
207 | .long 0 # Size of initialized data | |
208 | # on disk | |
209 | .long 0x0 # startup_{32,64} | |
210 | .long 0 # PointerToRelocations | |
211 | .long 0 # PointerToLineNumbers | |
212 | .word 0 # NumberOfRelocations | |
213 | .word 0 # NumberOfLineNumbers | |
214 | .long 0x60500020 # Characteristics (section flags) | |
215 | ||
216 | # | |
217 | # The EFI application loader requires a relocation section | |
743628e8 JJ |
218 | # because EFI applications must be relocatable. The .reloc |
219 | # offset & size fields are filled in by build.c. | |
291f3632 MF |
220 | # |
221 | .ascii ".reloc" | |
222 | .byte 0 | |
223 | .byte 0 | |
2e064b1e JJ |
224 | .long 0 |
225 | .long 0 | |
226 | .long 0 # SizeOfRawData | |
227 | .long 0 # PointerToRawData | |
291f3632 MF |
228 | .long 0 # PointerToRelocations |
229 | .long 0 # PointerToLineNumbers | |
230 | .word 0 # NumberOfRelocations | |
231 | .word 0 # NumberOfLineNumbers | |
232 | .long 0x42100040 # Characteristics (section flags) | |
743628e8 JJ |
233 | |
234 | # | |
235 | # The offset & size fields are filled in by build.c. | |
236 | # | |
237 | .ascii ".text" | |
238 | .byte 0 | |
239 | .byte 0 | |
240 | .byte 0 | |
241 | .long 0 | |
242 | .long 0x0 # startup_{32,64} | |
243 | .long 0 # Size of initialized data | |
244 | # on disk | |
245 | .long 0x0 # startup_{32,64} | |
246 | .long 0 # PointerToRelocations | |
247 | .long 0 # PointerToLineNumbers | |
248 | .word 0 # NumberOfRelocations | |
249 | .word 0 # NumberOfLineNumbers | |
250 | .long 0x60500020 # Characteristics (section flags) | |
251 | ||
c7fb93ec MB |
252 | # |
253 | # The offset & size fields are filled in by build.c. | |
254 | # | |
255 | .ascii ".bss" | |
256 | .byte 0 | |
257 | .byte 0 | |
258 | .byte 0 | |
259 | .byte 0 | |
260 | .long 0 | |
261 | .long 0x0 | |
262 | .long 0 # Size of initialized data | |
263 | # on disk | |
264 | .long 0x0 | |
265 | .long 0 # PointerToRelocations | |
266 | .long 0 # PointerToLineNumbers | |
267 | .word 0 # NumberOfRelocations | |
268 | .word 0 # NumberOfLineNumbers | |
269 | .long 0xc8000080 # Characteristics (section flags) | |
270 | ||
291f3632 | 271 | #endif /* CONFIG_EFI_STUB */ |
62607313 PA |
272 | |
273 | # Kernel attributes; used by setup. This is part 1 of the | |
274 | # header, from the old boot sector. | |
275 | ||
276 | .section ".header", "a" | |
09c205af PA |
277 | .globl sentinel |
278 | sentinel: .byte 0xff, 0xff /* Used to detect broken loaders */ | |
279 | ||
62607313 PA |
280 | .globl hdr |
281 | hdr: | |
5e47c478 | 282 | setup_sects: .byte 0 /* Filled in by build.c */ |
62607313 | 283 | root_flags: .word ROOT_RDONLY |
5e47c478 PA |
284 | syssize: .long 0 /* Filled in by build.c */ |
285 | ram_size: .word 0 /* Obsolete */ | |
62607313 | 286 | vid_mode: .word SVGA_MODE |
5e47c478 | 287 | root_dev: .word 0 /* Filled in by build.c */ |
62607313 PA |
288 | boot_flag: .word 0xAA55 |
289 | ||
290 | # offset 512, entry point | |
291 | ||
292 | .globl _start | |
293 | _start: | |
294 | # Explicitly enter this as bytes, or the assembler | |
295 | # tries to generate a 3-byte jump here, which causes | |
296 | # everything else to push off to the wrong offset. | |
297 | .byte 0xeb # short (2-byte) jump | |
298 | .byte start_of_setup-1f | |
299 | 1: | |
300 | ||
301 | # Part 2 of the header, from the old setup.S | |
302 | ||
303 | .ascii "HdrS" # header signature | |
7d453eee | 304 | .word 0x020d # header version number (>= 0x0105) |
62607313 PA |
305 | # or else old loadlin-1.5 will fail) |
306 | .globl realmode_swtch | |
307 | realmode_swtch: .word 0, 0 # default_switch, SETUPSEG | |
5e47c478 PA |
308 | start_sys_seg: .word SYSSEG # obsolete and meaningless, but just |
309 | # in case something decided to "use" it | |
62607313 PA |
310 | .word kernel_version-512 # pointing to kernel version string |
311 | # above section of header is compatible | |
312 | # with loadlin-1.5 (header v1.5). Don't | |
313 | # change it. | |
314 | ||
5e47c478 PA |
315 | type_of_loader: .byte 0 # 0 means ancient bootloader, newer |
316 | # bootloaders know to change this. | |
395cf969 | 317 | # See Documentation/x86/boot.txt for |
62607313 PA |
318 | # assigned ids |
319 | ||
320 | # flags, unused bits must be zero (RFU) bit within loadflags | |
321 | loadflags: | |
09c205af | 322 | .byte LOADED_HIGH # The kernel is to be loaded high |
62607313 PA |
323 | |
324 | setup_move_size: .word 0x8000 # size to move, when setup is not | |
325 | # loaded at 0x90000. We will move setup | |
326 | # to 0x90000 then just before jumping | |
327 | # into the kernel. However, only the | |
328 | # loader knows how much data behind | |
329 | # us also needs to be loaded. | |
330 | ||
331 | code32_start: # here loaders can put a different | |
332 | # start address for 32-bit code. | |
62607313 | 333 | .long 0x100000 # 0x100000 = default for big kernel |
62607313 PA |
334 | |
335 | ramdisk_image: .long 0 # address of loaded ramdisk image | |
336 | # Here the loader puts the 32-bit | |
337 | # address where it loaded the image. | |
338 | # This only will be read by the kernel. | |
339 | ||
340 | ramdisk_size: .long 0 # its size in bytes | |
341 | ||
342 | bootsect_kludge: | |
343 | .long 0 # obsolete | |
344 | ||
6b6815c6 PA |
345 | heap_end_ptr: .word _end+STACK_SIZE-512 |
346 | # (Header version 0x0201 or later) | |
62607313 PA |
347 | # space from here (exclusive) down to |
348 | # end of setup code can be used by setup | |
349 | # for local heap purposes. | |
350 | ||
5031296c PA |
351 | ext_loader_ver: |
352 | .byte 0 # Extended boot loader version | |
353 | ext_loader_type: | |
354 | .byte 0 # Extended boot loader type | |
355 | ||
62607313 PA |
356 | cmd_line_ptr: .long 0 # (Header version 0x0202 or later) |
357 | # If nonzero, a 32-bit pointer | |
358 | # to the kernel command line. | |
359 | # The command line should be | |
360 | # located between the start of | |
361 | # setup and the end of low | |
362 | # memory (0xa0000), or it may | |
363 | # get overwritten before it | |
364 | # gets read. If this field is | |
365 | # used, there is no longer | |
366 | # anything magical about the | |
367 | # 0x90000 segment; the setup | |
368 | # can be located anywhere in | |
369 | # low memory 0x10000 or higher. | |
370 | ||
3e920b53 | 371 | initrd_addr_max: .long 0x7fffffff |
62607313 PA |
372 | # (Header version 0x0203 or later) |
373 | # The highest safe address for | |
374 | # the contents of an initrd | |
cf8fa920 PA |
375 | # The current kernel allows up to 4 GB, |
376 | # but leave it at 2 GB to avoid | |
377 | # possible bootloader bugs. | |
62607313 PA |
378 | |
379 | kernel_alignment: .long CONFIG_PHYSICAL_ALIGN #physical addr alignment | |
380 | #required for protected mode | |
381 | #kernel | |
382 | #ifdef CONFIG_RELOCATABLE | |
383 | relocatable_kernel: .byte 1 | |
384 | #else | |
385 | relocatable_kernel: .byte 0 | |
386 | #endif | |
37ba7ab5 | 387 | min_alignment: .byte MIN_KERNEL_ALIGN_LG2 # minimum alignment |
09c205af PA |
388 | |
389 | xloadflags: | |
390 | #ifdef CONFIG_X86_64 | |
391 | # define XLF0 XLF_KERNEL_64 /* 64-bit kernel */ | |
392 | #else | |
393 | # define XLF0 0 | |
394 | #endif | |
ee92d815 | 395 | |
745c5167 | 396 | #if defined(CONFIG_RELOCATABLE) && defined(CONFIG_X86_64) |
ee92d815 YL |
397 | /* kernel/boot_param/ramdisk could be loaded above 4g */ |
398 | # define XLF1 XLF_CAN_BE_LOADED_ABOVE_4G | |
399 | #else | |
400 | # define XLF1 0 | |
401 | #endif | |
402 | ||
09c205af | 403 | #ifdef CONFIG_EFI_STUB |
7d453eee MF |
404 | # ifdef CONFIG_EFI_MIXED |
405 | # define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64) | |
09c205af | 406 | # else |
7d453eee MF |
407 | # ifdef CONFIG_X86_64 |
408 | # define XLF23 XLF_EFI_HANDOVER_64 /* 64-bit EFI handover ok */ | |
409 | # else | |
410 | # define XLF23 XLF_EFI_HANDOVER_32 /* 32-bit EFI handover ok */ | |
411 | # endif | |
09c205af PA |
412 | # endif |
413 | #else | |
414 | # define XLF23 0 | |
415 | #endif | |
456a29dd | 416 | |
2965faa5 | 417 | #if defined(CONFIG_X86_64) && defined(CONFIG_EFI) && defined(CONFIG_KEXEC_CORE) |
456a29dd DY |
418 | # define XLF4 XLF_EFI_KEXEC |
419 | #else | |
420 | # define XLF4 0 | |
421 | #endif | |
422 | ||
423 | .word XLF0 | XLF1 | XLF23 | XLF4 | |
62607313 PA |
424 | |
425 | cmdline_size: .long COMMAND_LINE_SIZE-1 #length of the command line, | |
426 | #added with boot protocol | |
427 | #version 2.06 | |
428 | ||
a24e7851 RR |
429 | hardware_subarch: .long 0 # subarchitecture, added with 2.07 |
430 | # default to 0 for normal x86 PC | |
431 | ||
432 | hardware_subarch_data: .quad 0 | |
433 | ||
77d1a499 PA |
434 | payload_offset: .long ZO_input_data |
435 | payload_length: .long ZO_z_input_len | |
099e1377 | 436 | |
8b664aa6 HY |
437 | setup_data: .quad 0 # 64-bit physical pointer to |
438 | # single linked list of | |
439 | # struct setup_data | |
440 | ||
37ba7ab5 PA |
441 | pref_address: .quad LOAD_PHYSICAL_ADDR # preferred load addr |
442 | ||
4252db10 BH |
443 | # |
444 | # Getting to provably safe in-place decompression is hard. Worst case | |
445 | # behaviours need to be analyzed. Here let's take the decompression of | |
446 | # a gzip-compressed kernel as example, to illustrate it: | |
447 | # | |
448 | # The file layout of gzip compressed kernel is: | |
449 | # | |
450 | # magic[2] | |
451 | # method[1] | |
452 | # flags[1] | |
453 | # timestamp[4] | |
454 | # extraflags[1] | |
455 | # os[1] | |
456 | # compressed data blocks[N] | |
457 | # crc[4] orig_len[4] | |
458 | # | |
459 | # ... resulting in +18 bytes overhead of uncompressed data. | |
460 | # | |
461 | # (For more information, please refer to RFC 1951 and RFC 1952.) | |
462 | # | |
463 | # Files divided into blocks | |
464 | # 1 bit (last block flag) | |
465 | # 2 bits (block type) | |
466 | # | |
467 | # 1 block occurs every 32K -1 bytes or when there 50% compression | |
468 | # has been achieved. The smallest block type encoding is always used. | |
469 | # | |
470 | # stored: | |
471 | # 32 bits length in bytes. | |
472 | # | |
473 | # fixed: | |
474 | # magic fixed tree. | |
475 | # symbols. | |
476 | # | |
477 | # dynamic: | |
478 | # dynamic tree encoding. | |
479 | # symbols. | |
480 | # | |
481 | # | |
482 | # The buffer for decompression in place is the length of the uncompressed | |
483 | # data, plus a small amount extra to keep the algorithm safe. The | |
484 | # compressed data is placed at the end of the buffer. The output pointer | |
485 | # is placed at the start of the buffer and the input pointer is placed | |
486 | # where the compressed data starts. Problems will occur when the output | |
487 | # pointer overruns the input pointer. | |
488 | # | |
489 | # The output pointer can only overrun the input pointer if the input | |
490 | # pointer is moving faster than the output pointer. A condition only | |
491 | # triggered by data whose compressed form is larger than the uncompressed | |
492 | # form. | |
493 | # | |
494 | # The worst case at the block level is a growth of the compressed data | |
495 | # of 5 bytes per 32767 bytes. | |
496 | # | |
497 | # The worst case internal to a compressed block is very hard to figure. | |
498 | # The worst case can at least be bounded by having one bit that represents | |
499 | # 32764 bytes and then all of the rest of the bytes representing the very | |
500 | # very last byte. | |
501 | # | |
502 | # All of which is enough to compute an amount of extra data that is required | |
503 | # to be safe. To avoid problems at the block level allocating 5 extra bytes | |
504 | # per 32767 bytes of data is sufficient. To avoid problems internal to a | |
505 | # block adding an extra 32767 bytes (the worst case uncompressed block size) | |
506 | # is sufficient, to ensure that in the worst case the decompressed data for | |
507 | # block will stop the byte before the compressed data for a block begins. | |
508 | # To avoid problems with the compressed data's meta information an extra 18 | |
509 | # bytes are needed. Leading to the formula: | |
510 | # | |
d607251b | 511 | # extra_bytes = (uncompressed_size >> 12) + 32768 + 18 |
4252db10 BH |
512 | # |
513 | # Adding 8 bytes per 32K is a bit excessive but much easier to calculate. | |
514 | # Adding 32768 instead of 32767 just makes for round numbers. | |
4252db10 BH |
515 | # |
516 | # Above analysis is for decompressing gzip compressed kernel only. Up to | |
517 | # now 6 different decompressor are supported all together. And among them | |
518 | # xz stores data in chunks and has maximum chunk of 64K. Hence safety | |
519 | # margin should be updated to cover all decompressors so that we don't | |
520 | # need to deal with each of them separately. Please check | |
521 | # the description in lib/decompressor_xxx.c for specific information. | |
522 | # | |
523 | # extra_bytes = (uncompressed_size >> 12) + 65536 + 128 | |
4252db10 | 524 | |
d607251b YL |
525 | #define ZO_z_extra_bytes ((ZO_z_output_len >> 12) + 65536 + 128) |
526 | #if ZO_z_output_len > ZO_z_input_len | |
527 | # define ZO_z_extract_offset (ZO_z_output_len + ZO_z_extra_bytes - \ | |
528 | ZO_z_input_len) | |
529 | #else | |
530 | # define ZO_z_extract_offset ZO_z_extra_bytes | |
531 | #endif | |
532 | ||
533 | /* | |
534 | * The extract_offset has to be bigger than ZO head section. Otherwise when | |
535 | * the head code is running to move ZO to the end of the buffer, it will | |
536 | * overwrite the head code itself. | |
537 | */ | |
538 | #if (ZO__ehead - ZO_startup_32) > ZO_z_extract_offset | |
539 | # define ZO_z_min_extract_offset ((ZO__ehead - ZO_startup_32 + 4095) & ~4095) | |
540 | #else | |
541 | # define ZO_z_min_extract_offset ((ZO_z_extract_offset + 4095) & ~4095) | |
542 | #endif | |
543 | ||
544 | #define ZO_INIT_SIZE (ZO__end - ZO_startup_32 + ZO_z_min_extract_offset) | |
545 | ||
37ba7ab5 PA |
546 | #define VO_INIT_SIZE (VO__end - VO__text) |
547 | #if ZO_INIT_SIZE > VO_INIT_SIZE | |
d607251b | 548 | # define INIT_SIZE ZO_INIT_SIZE |
37ba7ab5 | 549 | #else |
d607251b | 550 | # define INIT_SIZE VO_INIT_SIZE |
37ba7ab5 | 551 | #endif |
d607251b | 552 | |
37ba7ab5 | 553 | init_size: .long INIT_SIZE # kernel initialization size |
86134a1b | 554 | handover_offset: .long 0 # Filled in by build.c |
37ba7ab5 | 555 | |
62607313 PA |
556 | # End of setup header ##################################################### |
557 | ||
7a734e7d | 558 | .section ".entrytext", "ax" |
62607313 | 559 | start_of_setup: |
62607313 PA |
560 | # Force %es = %ds |
561 | movw %ds, %ax | |
562 | movw %ax, %es | |
563 | cld | |
564 | ||
16252da6 JR |
565 | # Apparently some ancient versions of LILO invoked the kernel with %ss != %ds, |
566 | # which happened to work by accident for the old code. Recalculate the stack | |
567 | # pointer if %ss is invalid. Otherwise leave it alone, LOADLIN sets up the | |
568 | # stack behind its own code, so we can't blindly put it directly past the heap. | |
6b6815c6 | 569 | |
6b6815c6 PA |
570 | movw %ss, %dx |
571 | cmpw %ax, %dx # %ds == %ss? | |
572 | movw %sp, %dx | |
16252da6 JR |
573 | je 2f # -> assume %sp is reasonably set |
574 | ||
575 | # Invalid %ss, make up a new stack | |
576 | movw $_end, %dx | |
577 | testb $CAN_USE_HEAP, loadflags | |
578 | jz 1f | |
579 | movw heap_end_ptr, %dx | |
580 | 1: addw $STACK_SIZE, %dx | |
581 | jnc 2f | |
582 | xorw %dx, %dx # Prevent wraparound | |
6b6815c6 | 583 | |
16252da6 | 584 | 2: # Now %dx should point to the end of our stack space |
6b6815c6 PA |
585 | andw $~3, %dx # dword align (might as well...) |
586 | jnz 3f | |
587 | movw $0xfffc, %dx # Make sure we're not zero | |
16252da6 | 588 | 3: movw %ax, %ss |
6b6815c6 PA |
589 | movzwl %dx, %esp # Clear upper half of %esp |
590 | sti # Now we should have a working stack | |
591 | ||
592 | # We will have entered with %cs = %ds+0x20, normalize %cs so | |
593 | # it is on par with the other segments. | |
594 | pushw %ds | |
595 | pushw $6f | |
596 | lretw | |
597 | 6: | |
62607313 PA |
598 | |
599 | # Check signature at end of setup | |
600 | cmpl $0x5a5aaa55, setup_sig | |
601 | jne setup_bad | |
602 | ||
603 | # Zero the bss | |
604 | movw $__bss_start, %di | |
605 | movw $_end+3, %cx | |
606 | xorl %eax, %eax | |
607 | subw %di, %cx | |
608 | shrw $2, %cx | |
609 | rep; stosl | |
610 | ||
611 | # Jump to C code (should not return) | |
612 | calll main | |
613 | ||
614 | # Setup corrupt somehow... | |
615 | setup_bad: | |
616 | movl $setup_corrupt, %eax | |
617 | calll puts | |
618 | # Fall through... | |
619 | ||
620 | .globl die | |
621 | .type die, @function | |
622 | die: | |
623 | hlt | |
624 | jmp die | |
625 | ||
bbc15f46 | 626 | .size die, .-die |
62607313 PA |
627 | |
628 | .section ".initdata", "a" | |
629 | setup_corrupt: | |
630 | .byte 7 | |
8b608d2f | 631 | .string "No setup signature found...\n" |