| blob | 2e943465d43da7581cda950ddedbf200ccf20772 |
1 ;; -----------------------------------------------------------------------
2 ;;
3 ;; Copyright 1994-2009 H. Peter Anvin - All Rights Reserved
4 ;; Copyright 2009-2010 Intel Corporation; author: H. Peter Anvin
5 ;;
6 ;; This program is free software; you can redistribute it and/or modify
7 ;; it under the terms of the GNU General Public License as published by
8 ;; the Free Software Foundation, Inc., 53 Temple Place Ste 330,
9 ;; Boston MA 02111-1307, USA; either version 2 of the License, or
10 ;; (at your option) any later version; incorporated herein by reference.
11 ;;
12 ;; -----------------------------------------------------------------------
14 ;;
15 ;; runkernel.inc
16 ;;
17 ;; Common code for running a Linux kernel
18 ;;
20 ;
21 ; Hook macros, that may or may not be defined
22 ;
23 %ifndef HAVE_UNLOAD_PREP
24 %macro UNLOAD_PREP 0
25 %endmacro
26 %endif
28 ;
29 ; A Linux kernel consists of three parts: boot sector, setup code, and
30 ; kernel code. The boot sector is never executed when using an external
31 ; booting utility, but it contains some status bytes that are necessary.
32 ;
33 ; First check that our kernel is at least 1K, or else it isn't long
34 ; enough to have the appropriate headers.
35 ;
36 ; We used to require the kernel to be 64K or larger, but it has gotten
37 ; popular to use the Linux kernel format for other things, which may
38 ; not be so large.
39 ;
40 ; Additionally, we used to have a test for 8 MB or smaller. Equally
41 ; obsolete.
42 ;
43 is_linux_kernel:
44 push si ; <A> file pointer
46 ;
47 ; Now start transferring the kernel
48 ;
49 push word real_mode_seg
50 pop es
52 ;
53 ; Start by loading the bootsector/setup code, to see if we need to
54 ; do something funky. It should fit in the first 32K (loading 64K won't
55 ; work since we might have funny stuff up near the end of memory).
56 ;
57 call abort_check ; Check for abort key
58 mov cx,8000h ; Half a moby (32K)
59 xor bx,bx
60 pop si ; <A> file pointer
61 pm_call getfsbytes
62 cmp cx,1024
63 jb kernel_corrupt
64 cmp word [es:bs_bootsign],0AA55h
65 jne kernel_corrupt ; Boot sec signature missing
67 ;
68 ; Save the file pointer for later...
69 ;
70 push si ; <A> file pointer
72 ;
73 ; Construct the command line (append options have already been copied)
74 ;
75 construct_cmdline:
76 mov di,[CmdLinePtr]
77 mov si,boot_image ; BOOT_IMAGE=
78 mov cx,boot_image_len
79 rep movsb
80 mov si,KernelName ; Unmangled kernel name
81 call strcpy
82 mov byte [es:di-1],' ' ; Follow by space
84 call do_ip_append ; Handle IPAppend
86 mov si,[CmdOptPtr] ; Options from user input
87 call strcpy
89 ;
90 ; Scan through the command line for anything that looks like we might be
91 ; interested in. The original version of this code automatically assumed
92 ; the first option was BOOT_IMAGE=, but that is no longer certain.
93 ;
94 parse_cmdline:
95 mov di,cmd_line_here
96 .skipspace: mov al,[es:di]
97 inc di
98 .skipspace_loaded:
99 and al,al
100 jz cmdline_end
101 cmp al,' '
102 jbe .skipspace
103 dec di
105 ; ES:DI now points to the beginning of an option
106 mov si,options_list
107 .next_opt:
108 movzx cx,byte [si]
109 jcxz .skip_opt
110 push di
111 inc si
112 repe cmpsb
113 jne .no_match
115 ; This either needs to have been an option with parameter,
116 ; or be followed by EOL/whitespace
117 mov ax,[es:di-1] ; AL = last chr; AH = following
118 cmp al,'='
119 je .is_match
120 cmp ah,' '
121 ja .no_match
122 .is_match:
123 pop ax ; Drop option pointer on stack
124 call [si]
125 .skip_opt:
126 mov al,[es:di]
127 inc di
128 cmp al,' '
129 ja .skip_opt
130 jmp .skipspace_loaded
131 .no_match:
132 pop di
133 add si,cx ; Skip remaining bytes
134 inc si ; Skip function pointer
135 inc si
136 jmp .next_opt
138 opt_vga:
139 mov ax,[es:di-1]
140 mov bx,-1
141 cmp ax,'=n' ; vga=normal
142 je .vc0
143 dec bx ; bx <- -2
144 cmp ax,'=e' ; vga=ext
145 je .vc0
146 dec bx ; bx <- -3
147 cmp ax,'=a' ; vga=ask
148 je .vc0
149 mov bx,0x0f04 ; bx <- 0x0f04 (current mode)
150 cmp ax,'=c' ; vga=current
151 je .vc0
152 call parseint_esdi ; vga=<number>
153 jc .skip ; Not an integer
154 .vc0: mov [es:bs_vidmode],bx ; Set video mode
155 .skip:
156 ret
158 opt_mem:
159 call parseint_esdi
160 jc .skip
161 %if HIGHMEM_SLOP != 0
162 sub ebx,HIGHMEM_SLOP
163 %endif
164 mov [MyHighMemSize],ebx
165 .skip:
166 ret
168 opt_quiet:
169 mov byte [QuietBoot],QUIET_FLAG
170 ret
172 %if IS_PXELINUX
173 opt_keeppxe:
174 or byte [KeepPXE],1 ; KeepPXE set by command line
175 ret
176 %endif
178 opt_initrd:
179 mov ax,di
180 cmp byte [es:di],' '
181 ja .have_initrd
182 xor ax,ax
183 .have_initrd:
184 mov [InitRDPtr],ax
185 ret
187 ;
188 ; After command line parsing...
189 ;
190 cmdline_end:
191 sub di,cmd_line_here
192 mov [CmdLineLen],di ; Length including final null
194 ;
195 ; Now check if we have a large kernel, which needs to be loaded high
196 ;
197 prepare_header:
198 mov dword [RamdiskMax], HIGHMEM_MAX ; Default initrd limit
199 cmp dword [es:su_header],HEADER_ID ; New setup code ID
200 jne old_kernel ; Old kernel, load low
201 mov ax,[es:su_version]
202 mov [KernelVersion],ax
203 cmp ax,0200h ; Setup code version 2.0
204 jb old_kernel ; Old kernel, load low
205 cmp ax,0201h ; Version 2.01+?
206 jb new_kernel ; If 2.00, skip this step
207 ; Set up the heap (assuming loading high for now)
208 mov word [es:su_heapend],linux_stack-512
209 or byte [es:su_loadflags],80h ; Let the kernel know we care
210 cmp ax,0203h ; Version 2.03+?
211 jb new_kernel ; Not 2.03+
212 mov eax,[es:su_ramdisk_max]
213 mov [RamdiskMax],eax ; Set the ramdisk limit
215 ;
216 ; We definitely have a new-style kernel. Let the kernel know who we are,
217 ; and that we are clueful
218 ;
219 new_kernel:
220 mov byte [es:su_loader],my_id ; Show some ID
221 xor eax,eax
222 mov [es:su_ramdisklen],eax ; No initrd loaded yet
224 ;
225 ; About to load the kernel. This is a modern kernel, so use the boot flags
226 ; we were provided.
227 ;
228 mov al,[es:su_loadflags]
229 or al,[QuietBoot] ; Set QUIET_FLAG if needed
230 mov [es:su_loadflags],al
231 mov [LoadFlags],al
233 any_kernel:
234 mov si,loading_msg
235 call writestr_qchk
236 mov si,KernelName ; Print kernel name part of
237 call writestr_qchk ; "Loading" message
239 ;
240 ; Load the kernel. We always load it at 100000h even if we're supposed to
241 ; load it "low"; for a "low" load we copy it down to low memory right before
242 ; jumping to it.
243 ;
244 read_kernel:
245 movzx ax,byte [es:bs_setupsecs] ; Setup sectors
246 and ax,ax
247 jnz .sects_ok
248 mov al,4 ; 0 = 4 setup sectors
249 .sects_ok:
250 inc ax ; Including the boot sector
251 mov [SetupSecs],ax
253 call dot_pause
255 ;
256 ; Move the stuff beyond the setup code to high memory at 100000h
257 ;
258 movzx esi,word [SetupSecs] ; Setup sectors
259 shl si,9 ; Convert to bytes
260 mov ecx,8000h ; 32K
261 sub ecx,esi ; Number of bytes to copy
262 add esi,core_real_mode ; Pointer to source
263 mov edi,free_high_memory ; Copy to free high memory
265 call bcopy ; Transfer to high memory
267 pop si ; <A> File pointer
268 and si,si ; EOF already?
269 jz high_load_done
271 ; On exit EDI -> where to load the rest
273 mov bx,dot_pause
274 or eax,-1 ; Load the whole file
275 mov dx,3 ; Pad to dword
276 call load_high
278 high_load_done:
279 mov [KernelEnd],edi
280 mov ax,real_mode_seg ; Set to real mode seg
281 mov es,ax
283 mov si,dot_msg
284 call writestr_qchk
286 ;
287 ; Some older kernels (1.2 era) would have more than 4 setup sectors, but
288 ; would not rely on the boot protocol to manage that. These kernels fail
289 ; if they see protected-mode kernel data after the setup sectors, so
290 ; clear that memory.
291 ;
292 push di
293 mov di,[SetupSecs]
294 shl di,9
295 xor eax,eax
296 mov cx,cmd_line_here
297 sub cx,di
298 shr cx,2
299 rep stosd
300 pop di
302 ;
303 ; Now see if we have an initial RAMdisk; if so, do requisite computation
304 ; We know we have a new kernel; the old_kernel code already will have objected
305 ; if we tried to load initrd using an old kernel
306 ;
307 load_initrd:
308 ; Cap the ramdisk memory range if appropriate
309 mov eax,[RamdiskMax]
310 cmp eax,[MyHighMemSize]
311 ja .ok
312 mov [MyHighMemSize],eax
313 .ok:
314 xor eax,eax
315 cmp [InitRDPtr],ax
316 jz .noinitrd
317 call parse_load_initrd
318 .noinitrd:
320 ;
321 ; Abandon hope, ye that enter here! We do no longer permit aborts.
322 ;
323 call abort_check ; Last chance!!
325 mov si,ready_msg
326 call writestr_qchk
328 UNLOAD_PREP ; Module-specific hook
330 ;
331 ; Now, if we were supposed to load "low", copy the kernel down to 10000h
332 ; and the real mode stuff to 90000h. We assume that all bzImage kernels are
333 ; capable of starting their setup from a different address.
334 ;
335 mov ax,real_mode_seg
336 mov es,ax
337 mov fs,ax
339 ;
340 ; If the default root device is set to FLOPPY (0000h), change to
341 ; /dev/fd0 (0200h)
342 ;
343 cmp word [es:bs_rootdev],byte 0
344 jne root_not_floppy
345 mov word [es:bs_rootdev],0200h
346 root_not_floppy:
348 ;
349 ; Copy command line. Unfortunately, the old kernel boot protocol requires
350 ; the command line to exist in the 9xxxxh range even if the rest of the
351 ; setup doesn't.
352 ;
353 setup_command_line:
354 mov dx,[KernelVersion]
355 test byte [LoadFlags],LOAD_HIGH
356 jz .need_high_cmdline
357 cmp dx,0202h ; Support new cmdline protocol?
358 jb .need_high_cmdline
359 ; New cmdline protocol
360 ; Store 32-bit (flat) pointer to command line
361 ; This is the "high" location, since we have bzImage
362 mov dword [fs:su_cmd_line_ptr],cmd_line
363 mov word [HeapEnd],linux_stack
364 mov word [fs:su_heapend],linux_stack-512
365 jmp .setup_done
367 .need_high_cmdline:
368 ;
369 ; Copy command line down to fit in high conventional memory
370 ; -- this happens if we have a zImage kernel or the protocol
371 ; is less than 2.02.
372 ;
373 mov si,cmd_line_here
374 mov di,old_cmd_line_here
375 mov [fs:kern_cmd_magic],word CMD_MAGIC ; Store magic
376 mov [fs:kern_cmd_offset],di ; Store pointer
377 mov word [HeapEnd],old_linux_stack
378 mov ax,255 ; Max cmdline limit
379 cmp dx,0201h
380 jb .adjusted
381 ; Protocol 2.01+
382 mov word [fs:su_heapend],old_linux_stack-512
383 jbe .adjusted
384 ; Protocol 2.02+
385 ; Note that the only reason we would end up here is
386 ; because we have a zImage, so we anticipate the move
387 ; to 90000h already...
388 mov dword [fs:su_cmd_line_ptr],0x90000+old_cmd_line_here
389 mov ax,old_max_cmd_len ; 2.02+ allow a higher limit
390 .adjusted:
392 mov cx,[CmdLineLen]
393 cmp cx,ax
394 jna .len_ok
395 mov cx,ax ; Truncate the command line
396 .len_ok:
397 fs rep movsb
398 stosb ; Final null, note AL=0 already
399 mov [CmdLineEnd],di
400 cmp dx,0200h
401 jb .nomovesize
402 mov [es:su_movesize],di ; Tell the kernel what to move
403 .nomovesize:
404 .setup_done:
406 ;
407 ; Time to start setting up move descriptors
408 ;
409 setup_move:
410 mov di,trackbuf
411 xor cx,cx ; Number of descriptors
413 mov bx,es ; real_mode_seg
414 mov fs,bx
415 push ds ; We need DS == ES == CS here
416 pop es
418 mov edx,100000h
419 test byte [LoadFlags],LOAD_HIGH
420 jnz .loading_high
422 ; Loading low: move real_mode stuff to 90000h, then move the kernel down
423 mov eax,90000h
424 stosd
425 mov eax,core_real_mode
426 stosd
427 movzx eax,word [CmdLineEnd]
428 stosd
429 inc cx
430 mov edx,10000h ; Revised target address
431 mov bx,9000h ; Revised real mode segment
433 .loading_high:
434 mov eax,edx ; Target address of kernel
435 stosd
436 mov eax,free_high_memory ; Where currently loaded
437 stosd
438 neg eax
439 add eax,[KernelEnd]
440 stosd
441 inc cx
443 cmp word [InitRDPtr],0 ; Did we have an initrd?
444 je .no_initrd
446 mov eax,[fs:su_ramdiskat]
447 stosd
448 mov eax,[InitRDStart]
449 stosd
450 mov eax,[fs:su_ramdisklen]
451 stosd
452 inc cx
454 .no_initrd:
455 push dword run_linux_kernel
456 push cx ; descriptor list entries count
458 ; BX points to the final real mode segment, and will be loaded
459 ; into DS.
461 test byte [QuietBoot],QUIET_FLAG
462 jz replace_bootstrap
463 jmp replace_bootstrap_noclearmode
465 run_linux_kernel:
466 ;
467 ; Set up segment registers and the Linux real-mode stack
468 ; Note: ds == the real mode segment
469 ;
470 cli
471 mov ax,ds
472 mov ss,ax
473 mov sp,strict word linux_stack
474 ; Point HeapEnd to the immediate of the instruction above
475 HeapEnd equ $-2 ; Self-modifying code! Fun!
476 mov es,ax
477 mov fs,ax
478 mov gs,ax
480 ;
481 ; We're done... now RUN THAT KERNEL!!!!
482 ; Setup segment == real mode segment + 020h; we need to jump to offset
483 ; zero in the real mode segment.
484 ;
485 add ax,020h
486 push ax
487 push word 0h
488 retf
490 ;
491 ; Load an older kernel. Older kernels always have 4 setup sectors, can't have
492 ; initrd, and are always loaded low.
493 ;
494 old_kernel:
495 xor ax,ax
496 cmp word [InitRDPtr],ax ; Old kernel can't have initrd
497 je .load
498 mov si,err_oldkernel
499 jmp abort_load
500 .load:
501 mov byte [LoadFlags],al ; Always low
502 mov word [KernelVersion],ax ; Version 0.00
503 jmp any_kernel
505 ;
506 ; parse_load_initrd
507 ;
508 ; Parse an initrd= option and load the initrds. This sets
509 ; InitRDStart and InitRDEnd with dword padding between; we then
510 ; do a global memory shuffle to move it to the end of memory.
511 ;
512 ; On entry, EDI points to where to start loading.
513 ;
514 parse_load_initrd:
515 push es
516 push ds
517 mov ax,real_mode_seg
518 mov ds,ax
519 push cs
520 pop es ; DS == real_mode_seg, ES == CS
522 mov [cs:InitRDStart],edi
523 mov [cs:InitRDEnd],edi
525 mov si,[cs:InitRDPtr]
527 .get_chunk:
528 ; DS:SI points to the start of a name
530 mov bx,si
531 .find_end:
532 lodsb
533 cmp al,','
534 je .got_end
535 cmp al,' '
536 jbe .got_end
537 jmp .find_end
539 .got_end:
540 push ax ; Terminating character
541 push si ; Next filename (if any)
542 mov byte [si-1],0 ; Zero-terminate
543 mov si,bx ; Current filename
545 push di
546 mov di,InitRD ; Target buffer for mangled name
547 pm_call pm_mangle_name
548 pop di
549 call loadinitrd
551 pop si
552 pop ax
553 mov [si-1],al ; Restore ending byte
555 cmp al,','
556 je .get_chunk
558 ; Compute the initrd target location
559 ; Note: we round to a page boundary twice here. The first
560 ; time it is to make sure we don't use any fractional page
561 ; which may be valid RAM but which will be ignored by the
562 ; kernel (and therefore is inaccessible.) The second time
563 ; it is to make sure we start out on page boundary.
564 mov edx,[cs:InitRDEnd]
565 sub edx,[cs:InitRDStart]
566 mov [su_ramdisklen],edx
567 mov eax,[cs:MyHighMemSize]
568 and ax,0F000h ; Round to a page boundary
569 sub eax,edx
570 and ax,0F000h ; Round to a page boundary
571 mov [su_ramdiskat],eax
573 pop ds
574 pop es
575 ret
577 ;
578 ; Load RAM disk into high memory
579 ;
580 ; Input: InitRD - set to the mangled name of the initrd
581 ; EDI - location to load
582 ; Output: EDI - location for next initrd
583 ; InitRDEnd - updated
584 ;
585 loadinitrd:
586 push ds
587 push es
588 mov ax,cs ; CS == DS == ES
589 mov ds,ax
590 mov es,ax
591 push edi
592 mov di,InitRD
593 pm_call pm_searchdir ; Look for it in directory
594 pop edi
595 jz .notthere
597 push si
598 mov si,crlfloading_msg ; Write "Loading "
599 call writestr_qchk
600 mov si,InitRD ; Write ramdisk name
601 call writestr_qchk
602 mov si,dotdot_msg ; Write dots
603 call writestr_qchk
604 pop si
606 .li_skip_echo:
607 mov dx,3
608 mov bx,dot_pause
609 call load_high
610 mov [InitRDEnd],ebx
612 pop es
613 pop ds
614 ret
616 .notthere:
617 mov si,err_noinitrd
618 call writestr
619 mov si,InitRD
620 call writestr
621 mov si,crlf_msg
622 jmp abort_load
624 ;
625 ; writestr_qchk: writestr, except allows output to be suppressed
626 ; assumes CS == DS
627 ;
628 writestr_qchk:
629 test byte [QuietBoot],QUIET_FLAG
630 jz writestr
631 ret
633 section .data16
634 crlfloading_msg db CR, LF
635 loading_msg db 'Loading ', 0
636 dotdot_msg db '.'
637 dot_msg db '.', 0
638 ready_msg db 'ready.', CR, LF, 0
639 err_oldkernel db 'Cannot load a ramdisk with an old kernel image.'
640 db CR, LF, 0
641 err_noinitrd db CR, LF, 'Could not find ramdisk image: ', 0
643 boot_image db 'BOOT_IMAGE='
644 boot_image_len equ $-boot_image
646 ;
647 ; Command line options we'd like to take a look at
648 ;
649 %macro cmd_opt 2
650 %strlen cmd_opt_len %1
651 db cmd_opt_len
652 db %1
653 dw %2
654 %endmacro
655 options_list:
656 cmd_opt "vga=", opt_vga
657 cmd_opt "mem=", opt_mem
658 cmd_opt "quiet", opt_quiet
659 str_initrd equ $+1 ; Pointer to "initrd=" in memory
660 cmd_opt "initrd=", opt_initrd
661 %if IS_PXELINUX
662 cmd_opt "keeppxe", opt_keeppxe
663 %endif
664 db 0
666 section .bss16
667 alignb 4
668 MyHighMemSize resd 1 ; Possibly adjusted highmem size
669 RamdiskMax resd 1 ; Highest address for ramdisk
670 KernelSize resd 1 ; Size of kernel in bytes
671 KernelSects resd 1 ; Size of kernel in sectors
672 KernelEnd resd 1 ; Ending address of the kernel image
673 InitRDStart resd 1 ; Start of initrd (pre-relocation)
674 InitRDEnd resd 1 ; End of initrd (pre-relocation)
675 CmdLineLen resw 1 ; Length of command line including null
676 CmdLineEnd resw 1 ; End of the command line in real_mode_seg
677 SetupSecs resw 1 ; Number of setup sectors (+bootsect)
678 KernelVersion resw 1 ; Kernel protocol version
679 ;
680 ; These are derived from the command-line parser
681 ;
682 InitRDPtr resw 1 ; Pointer to initrd= option in command line
683 LoadFlags resb 1 ; Loadflags from kernel
684 QuietBoot resb 1 ; Set if a quiet boot is requested