mkinitrd-magellan/isolinux/runkernel.inc

;; $Id: runkernel.inc,v 1.1 2007-09-01 22:44:05 niro Exp $
;; -----------------------------------------------------------------------
;;   
;;   Copyright 1994-2005 H. Peter Anvin - All Rights Reserved
;;
;;   This program is free software; you can redistribute it and/or modify
;;   it under the terms of the GNU General Public License as published by
;;   the Free Software Foundation, Inc., 53 Temple Place Ste 330,
;;   Boston MA 02111-1307, USA; either version 2 of the License, or
;;   (at your option) any later version; incorporated herein by reference.
;;
;; -----------------------------------------------------------------------

;;
;; runkernel.inc
;; 
;; Common code for running a Linux kernel
;;

;
; Hook macros, that may or may not be defined
;
%ifndef HAVE_SPECIAL_APPEND
%macro SPECIAL_APPEND 0
%endmacro
%endif

%ifndef HAVE_UNLOAD_PREP
%macro UNLOAD_PREP 0
%endmacro
%endif

;
; A Linux kernel consists of three parts: boot sector, setup code, and
; kernel code.	The boot sector is never executed when using an external
; booting utility, but it contains some status bytes that are necessary.
;
; First check that our kernel is at least 1K and less than 8M (if it is
; more than 8M, we need to change the logic for loading it anyway...)
;
; We used to require the kernel to be 64K or larger, but it has gotten
; popular to use the Linux kernel format for other things, which may
; not be so large.
;
is_linux_kernel:
                cmp dx,80h			; 8 megs
		ja kernel_corrupt
		and dx,dx
		jnz kernel_sane
		cmp ax,1024			; Bootsect + 1 setup sect
		jb kernel_corrupt
kernel_sane:	push ax
		push dx
		push si
		mov si,loading_msg
                call cwritestr
;
; Now start transferring the kernel
;
		push word real_mode_seg
		pop es

		movzx eax,ax			; Fix this by using a 32-bit
		shl edx,16			; register for the kernel size
		or eax,edx
		mov [KernelSize],eax
		add eax,SECTOR_SIZE-1
		shr eax,SECTOR_SHIFT
                mov [KernelSects],eax		; Total sectors in kernel

;
; Now, if we transfer these straight, we'll hit 64K boundaries.	 Hence we
; have to see if we're loading more than 64K, and if so, load it step by
; step.
;

;
; Start by loading the bootsector/setup code, to see if we need to
; do something funky.  It should fit in the first 32K (loading 64K won't
; work since we might have funny stuff up near the end of memory).
; If we have larger than 32K clusters, yes, we're hosed.
;
		call abort_check		; Check for abort key
		mov ecx,8000h >> SECTOR_SHIFT	; Half a moby (32K)
		cmp ecx,[KernelSects]
		jna .normalkernel
		mov ecx,[KernelSects]
.normalkernel:
		sub [KernelSects],ecx
		xor bx,bx
                pop si                          ; Cluster pointer on stack
		call getfssec
                cmp word [es:bs_bootsign],0AA55h
		jne kernel_corrupt		; Boot sec signature missing

;
; Save the cluster pointer for later...
;
		push si
;
; Get the BIOS' idea of what the size of high memory is.
;
		call highmemsize
;
; Construct the command line (append options have already been copied)
;
construct_cmdline:
		mov di,[CmdLinePtr]
                mov si,boot_image        	; BOOT_IMAGE=
                mov cx,boot_image_len
                rep movsb
                mov si,KernelCName       	; Unmangled kernel name
                mov cx,[KernelCNameLen]
                rep movsb
                mov al,' '                      ; Space
                stosb

		SPECIAL_APPEND			; Module-specific hook

                mov si,[CmdOptPtr]              ; Options from user input
		call strcpy

;
; Scan through the command line for anything that looks like we might be
; interested in.  The original version of this code automatically assumed
; the first option was BOOT_IMAGE=, but that is no longer certain.
;
		mov si,cmd_line_here
		xor ax,ax
                mov [InitRDPtr],ax		; No initrd= option (yet)
                push es				; Set DS <- real_mode_seg
                pop ds
get_next_opt:   lodsb
		and al,al
		jz cmdline_end
		cmp al,' '
		jbe get_next_opt
		dec si
                mov eax,[si]
                cmp eax,'vga='
		je is_vga_cmd
                cmp eax,'mem='
		je is_mem_cmd
%if IS_PXELINUX
		cmp eax,'keep'			; Is it "keeppxe"?
		jne .notkeep
		cmp dword [si+3],'ppxe'
		jne .notkeep
		cmp byte [si+7],' '		; Must be whitespace or EOS
		ja .notkeep
		or byte [cs:KeepPXE],1
.notkeep:
%endif
                push es                         ; Save ES -> real_mode_seg
                push cs
                pop es                          ; Set ES <- normal DS
                mov di,initrd_cmd
		mov cx,initrd_cmd_len
		repe cmpsb
                jne .not_initrd

		cmp al,' '
		jbe .noramdisk
		mov [cs:InitRDPtr],si
		jmp .not_initrd
.noramdisk:
		xor ax,ax
		mov [cs:InitRDPtr],ax
.not_initrd:	pop es                          ; Restore ES -> real_mode_seg
skip_this_opt:  lodsb                           ; Load from command line
                cmp al,' '
                ja skip_this_opt
                dec si
                jmp short get_next_opt
is_vga_cmd:
                add si,4
                mov eax,[si-1]
                mov bx,-1
                cmp eax,'=nor'			; vga=normal
                je vc0
		dec bx				; bx <- -2
                cmp eax,'=ext'			; vga=ext
                je vc0
                dec bx				; bx <- -3
                cmp eax,'=ask'			; vga=ask
                je vc0
                call parseint                   ; vga=<number>
		jc skip_this_opt		; Not an integer
vc0:		mov [bs_vidmode],bx		; Set video mode
		jmp short skip_this_opt
is_mem_cmd:
                add si,4
                call parseint
		jc skip_this_opt		; Not an integer
%if HIGHMEM_SLOP != 0
		sub ebx,HIGHMEM_SLOP
%endif
		mov [cs:HighMemSize],ebx
		jmp short skip_this_opt
cmdline_end:
                push cs                         ; Restore standard DS
                pop ds
		sub si,cmd_line_here
		mov [CmdLineLen],si		; Length including final null
;
; Now check if we have a large kernel, which needs to be loaded high
;
		mov dword [RamdiskMax], HIGHMEM_MAX	; Default initrd limit
		cmp dword [es:su_header],HEADER_ID	; New setup code ID
		jne old_kernel		; Old kernel, load low
		cmp word [es:su_version],0200h	; Setup code version 2.0
		jb old_kernel		; Old kernel, load low
                cmp word [es:su_version],0201h	; Version 2.01+?
                jb new_kernel                   ; If 2.00, skip this step
                mov word [es:su_heapend],linux_stack	; Set up the heap
                or byte [es:su_loadflags],80h	; Let the kernel know we care
		cmp word [es:su_version],0203h	; Version 2.03+?
		jb new_kernel			; Not 2.03+
		mov eax,[es:su_ramdisk_max]
		mov [RamdiskMax],eax		; Set the ramdisk limit

;
; We definitely have a new-style kernel.  Let the kernel know who we are,
; and that we are clueful
;
new_kernel:
		mov byte [es:su_loader],my_id	; Show some ID
		movzx ax,byte [es:bs_setupsecs]	; Variable # of setup sectors
		mov [SetupSecs],ax
		xor eax,eax
		mov [es:su_ramdisklen],eax	; No initrd loaded yet

;
; About to load the kernel.  This is a modern kernel, so use the boot flags
; we were provided.
;
                mov al,[es:su_loadflags]
		mov [LoadFlags],al
;
; Load the kernel.  We always load it at 100000h even if we're supposed to
; load it "low"; for a "low" load we copy it down to low memory right before
; jumping to it.
;
read_kernel:
                mov si,KernelCName		; Print kernel name part of
                call cwritestr                  ; "Loading" message
                mov si,dotdot_msg		; Print dots
                call cwritestr

                mov eax,[HighMemSize]
		sub eax,100000h			; Load address
		cmp eax,[KernelSize]
		jb no_high_mem		; Not enough high memory
;
; Move the stuff beyond the setup code to high memory at 100000h
;
		movzx esi,word [SetupSecs]	; Setup sectors
		inc si				; plus 1 boot sector
                shl si,9			; Convert to bytes
                mov ecx,8000h			; 32K
		sub ecx,esi			; Number of bytes to copy
		push ecx
		add esi,(real_mode_seg << 4)	; Pointer to source
                mov edi,100000h                 ; Copy to address 100000h

                call bcopy			; Transfer to high memory

		; On exit EDI -> where to load the rest

                mov si,dot_msg			; Progress report
                call cwritestr
                call abort_check

		pop ecx				; Number of bytes in the initial portion
		pop si				; Restore file handle/cluster pointer
		mov eax,[KernelSize]
		sub eax,8000h			; Amount of kernel not yet loaded
		jbe high_load_done		; Zero left (tiny kernel)

		xor dx,dx			; No padding needed
		call load_high			; Copy the file

high_load_done:
		mov [KernelEnd],edi
                mov ax,real_mode_seg		; Set to real mode seg
                mov es,ax

                mov si,dot_msg
                call cwritestr

;
; Now see if we have an initial RAMdisk; if so, do requisite computation
; We know we have a new kernel; the old_kernel code already will have objected
; if we tried to load initrd using an old kernel
;
load_initrd:
                cmp word [InitRDPtr],0
                jz nk_noinitrd
		call parse_load_initrd
nk_noinitrd:
;
; Abandon hope, ye that enter here!  We do no longer permit aborts.
;
                call abort_check        	; Last chance!!

		mov si,ready_msg
		call cwritestr

		call vgaclearmode		; We can't trust ourselves after this

		UNLOAD_PREP			; Module-specific hook

;
; Now, if we were supposed to load "low", copy the kernel down to 10000h
; and the real mode stuff to 90000h.  We assume that all bzImage kernels are
; capable of starting their setup from a different address.
;
		mov ax,real_mode_seg
		mov fs,ax

;
; Copy command line.  Unfortunately, the kernel boot protocol requires
; the command line to exist in the 9xxxxh range even if the rest of the
; setup doesn't.
;
		cli				; In case of hooked interrupts
		test byte [LoadFlags],LOAD_HIGH
		jz need_high_cmdline
		cmp word [fs:su_version],0202h	; Support new cmdline protocol?
		jb need_high_cmdline
		; New cmdline protocol
		; Store 32-bit (flat) pointer to command line
		mov dword [fs:su_cmd_line_ptr],(real_mode_seg << 4) + cmd_line_here
		jmp short in_proper_place

need_high_cmdline:
;
; Copy command line up to 90000h
;
		mov ax,9000h			; Note AL <- 0
		mov es,ax
		mov si,cmd_line_here
		mov di,si
		mov [fs:kern_cmd_magic],word CMD_MAGIC ; Store magic
		mov [fs:kern_cmd_offset],di	; Store pointer

		mov cx,[CmdLineLen]
		cmp cx,255
		jna .len_ok
		mov cx,255			; Protocol < 0x202 has 255 as hard limit
.len_ok:
		fs rep movsb
		stosb				; Final null, note AL == 0 already

		push fs
		pop es

		test byte [LoadFlags],LOAD_HIGH
		jnz in_proper_place		; If high load, we're done

;
; Loading low; we can't assume it's safe to run in place.
;
; Copy real_mode stuff up to 90000h
;
		mov ax,9000h
		mov es,ax
		mov cx,[SetupSecs]
		inc cx				; Setup + boot sector
		shl cx,7			; Sectors -> dwords
		xor si,si
		xor di,di
		fs rep movsd			; Copy setup + boot sector
;
; Some kernels in the 1.2 ballpark but pre-bzImage have more than 4
; setup sectors, but the boot protocol had not yet been defined.  They
; rely on a signature to figure out if they need to copy stuff from
; the "protected mode" kernel area.  Unfortunately, we used that area
; as a transfer buffer, so it's going to find the signature there.
; Hence, zero the low 32K beyond the setup area.
;
		mov di,[SetupSecs]
		inc di				; Setup + boot sector
		mov cx,32768/512		; Sectors/32K
		sub cx,di			; Remaining sectors
		shl di,9			; Sectors -> bytes
		shl cx,7			; Sectors -> dwords
		xor eax,eax
		rep stosd			; Clear region
;
; Copy the kernel down to the "low" location
;
		mov ecx,[KernelSize]
		mov esi,100000h
		mov edi,10000h
		call bcopy

;
; Now everything is where it needs to be...
;
; When we get here, es points to the final segment, either
; 9000h or real_mode_seg
;
in_proper_place:

;
; If the default root device is set to FLOPPY (0000h), change to
; /dev/fd0 (0200h)
;
		cmp word [es:bs_rootdev],byte 0
		jne root_not_floppy
		mov word [es:bs_rootdev],0200h
root_not_floppy:

;
; Copy the disk table to high memory, then re-initialize the floppy
; controller
;
%if IS_SYSLINUX || IS_MDSLINUX
		lgs si,[cs:fdctab]
		mov di,linux_fdctab
		mov cx,6			; 12 bytes
		gs rep movsw
		mov [cs:fdctab],word linux_fdctab ; Save new floppy tab pos
		mov [cs:fdctab+2],es
%endif
;
; Linux wants the floppy motor shut off before starting the kernel,
; at least bootsect.S seems to imply so.
;
kill_motor:
		xor ax,ax
		xor dx,dx
		int 13h

;
; If we're debugging, wait for a keypress so we can read any debug messages
;
%ifdef debug
                xor ax,ax
                int 16h
%endif
;
; Set up segment registers and the Linux real-mode stack
; Note: es == the real mode segment
;
		cli
		mov bx,es
		mov ds,bx
		mov fs,bx
		mov gs,bx
		mov ss,bx
		mov sp,linux_stack
;
; We're done... now RUN THAT KERNEL!!!!
; Setup segment == real mode segment + 020h; we need to jump to offset
; zero in the real mode segment.
;
		add bx,020h
		push bx
		push word 0h
		retf

;
; Load an older kernel.  Older kernels always have 4 setup sectors, can't have
; initrd, and are always loaded low.
;
old_kernel:
               	cmp word [InitRDPtr],0		; Old kernel can't have initrd
                je load_old_kernel
                mov si,err_oldkernel
                jmp abort_load
load_old_kernel:
		mov word [SetupSecs],4		; Always 4 setup sectors
		mov byte [LoadFlags],0		; Always low
		jmp read_kernel

;
; parse_load_initrd
;
; Parse an initrd= option and load the initrds.  Note that we load
; from the high end of memory first, so we parse this option from
; left to right.
;
parse_load_initrd:
		push es
		push ds
		mov ax,real_mode_seg
		mov ds,ax
		push cs
		pop es			; DS == real_mode_seg, ES == CS

		mov si,[cs:InitRDPtr]
.find_end:
		lodsb
		cmp al,' '
		ja .find_end
		; Now SI points to one character beyond the
		; byte that ended this option.

.get_chunk:
		dec si

		; DS:SI points to a termination byte

		xor ax,ax
		xchg al,[si]		; Zero-terminate
		push si			; Save ending byte address
		push ax			; Save ending byte

.find_start:
		dec si
		cmp si,[cs:InitRDPtr]
		je .got_start
		cmp byte [si],','
		jne .find_start

		; It's a comma byte
		inc si

.got_start:
		push si
		mov di,InitRD		; Target buffer for mangled name
		call mangle_name
		call loadinitrd
		pop si

		pop ax
		pop di
		mov [di],al		; Restore ending byte

		cmp si,[cs:InitRDPtr]
		ja .get_chunk

		pop ds
		pop es
		ret

;
; Load RAM disk into high memory
;
; Input:	InitRD		- set to the mangled name of the initrd
;
loadinitrd:
		push ds
		push es
		mov ax,cs			; CS == DS == ES
		mov ds,ax
		mov es,ax
                mov si,InitRD
                mov di,InitRDCName
                call unmangle_name              ; Create human-readable name
                sub di,InitRDCName
                mov [InitRDCNameLen],di
                mov di,InitRD
                call searchdir                  ; Look for it in directory
		jz .notthere

		mov cx,dx
		shl ecx,16
		mov cx,ax			; ECX <- ram disk length

		mov ax,real_mode_seg
		mov es,ax

		push ecx			; Bytes to load
		cmp dword [es:su_ramdisklen],0
		je .nopadding			; Don't pad the last initrd
		add ecx,4095
		and cx,0F000h
.nopadding:
		add [es:su_ramdisklen],ecx
		mov edx,[HighMemSize]		; End of memory
		dec edx
		mov eax,[RamdiskMax]		; Highest address allowed by kernel
		cmp edx,eax
		jna .memsize_ok
		mov edx,eax			; Adjust to fit inside limit
.memsize_ok:
		inc edx
                and dx,0F000h			; Round down to 4K boundary
		sub edx,ecx			; Subtract size of ramdisk
                and dx,0F000h			; Round down to 4K boundary
		cmp edx,[KernelEnd]		; Are we hitting the kernel image?
		jb no_high_mem

                mov [es:su_ramdiskat],edx	; Load address
		mov [RamdiskMax],edx		; Next initrd loaded here

                mov edi,edx			; initrd load address
		push si
		mov si,crlfloading_msg		; Write "Loading "
		call cwritestr
                mov si,InitRDCName		; Write ramdisk name
                call cwritestr
                mov si,dotdot_msg		; Write dots
                call cwritestr
		pop si

		pop eax				; Bytes to load
		mov dx,0FFFh			; Pad to page
		call load_high			; Load the file

		pop es
		pop ds
		jmp crlf			; Print carriage return and return

.notthere:
                mov si,err_noinitrd
                call cwritestr
                mov si,InitRDCName
                call cwritestr
                mov si,crlf_msg
                jmp abort_load

no_high_mem:    				; Error routine
		mov si,err_nohighmem
                jmp abort_load

                ret

		section .data
boot_image      db 'BOOT_IMAGE='
boot_image_len  equ $-boot_image

		section .bss
		alignb 4
RamdiskMax	resd 1			; Highest address for ramdisk
KernelSize	resd 1			; Size of kernel in bytes
KernelSects	resd 1			; Size of kernel in sectors
KernelEnd	resd 1			; Ending address of the kernel image
CmdLineLen	resw 1			; Length of command line including null
SetupSecs	resw 1			; Number of setup sectors
InitRDPtr	resw 1			; Pointer to initrd= option in command line
LoadFlags	resb 1			; Loadflags from kernel
1	;; $Id: runkernel.inc,v 1.1 2007-09-01 22:44:05 niro Exp $
2	;; -----------------------------------------------------------------------
3	;;
4	;; Copyright 1994-2005 H. Peter Anvin - All Rights Reserved
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	;; -----------------------------------------------------------------------
13
14	;;
15	;; runkernel.inc
16	;;
17	;; Common code for running a Linux kernel
18	;;
19
20	;
21	; Hook macros, that may or may not be defined
22	;
23	%ifndef HAVE_SPECIAL_APPEND
24	%macro SPECIAL_APPEND 0
25	%endmacro
26	%endif
27
28	%ifndef HAVE_UNLOAD_PREP
29	%macro UNLOAD_PREP 0
30	%endmacro
31	%endif
32
33	;
34	; A Linux kernel consists of three parts: boot sector, setup code, and
35	; kernel code. The boot sector is never executed when using an external
36	; booting utility, but it contains some status bytes that are necessary.
37	;
38	; First check that our kernel is at least 1K and less than 8M (if it is
39	; more than 8M, we need to change the logic for loading it anyway...)
40	;
41	; We used to require the kernel to be 64K or larger, but it has gotten
42	; popular to use the Linux kernel format for other things, which may
43	; not be so large.
44	;
45	is_linux_kernel:
46	cmp dx,80h ; 8 megs
47	ja kernel_corrupt
48	and dx,dx
49	jnz kernel_sane
50	cmp ax,1024 ; Bootsect + 1 setup sect
51	jb kernel_corrupt
52	kernel_sane: push ax
53	push dx
54	push si
55	mov si,loading_msg
56	call cwritestr
57	;
58	; Now start transferring the kernel
59	;
60	push word real_mode_seg
61	pop es
62
63	movzx eax,ax ; Fix this by using a 32-bit
64	shl edx,16 ; register for the kernel size
65	or eax,edx
66	mov [KernelSize],eax
67	add eax,SECTOR_SIZE-1
68	shr eax,SECTOR_SHIFT
69	mov [KernelSects],eax ; Total sectors in kernel
70
71	;
72	; Now, if we transfer these straight, we'll hit 64K boundaries. Hence we
73	; have to see if we're loading more than 64K, and if so, load it step by
74	; step.
75	;
76
77	;
78	; Start by loading the bootsector/setup code, to see if we need to
79	; do something funky. It should fit in the first 32K (loading 64K won't
80	; work since we might have funny stuff up near the end of memory).
81	; If we have larger than 32K clusters, yes, we're hosed.
82	;
83	call abort_check ; Check for abort key
84	mov ecx,8000h >> SECTOR_SHIFT ; Half a moby (32K)
85	cmp ecx,[KernelSects]
86	jna .normalkernel
87	mov ecx,[KernelSects]
88	.normalkernel:
89	sub [KernelSects],ecx
90	xor bx,bx
91	pop si ; Cluster pointer on stack
92	call getfssec
93	cmp word [es:bs_bootsign],0AA55h
94	jne kernel_corrupt ; Boot sec signature missing
95
96	;
97	; Save the cluster pointer for later...
98	;
99	push si
100	;
101	; Get the BIOS' idea of what the size of high memory is.
102	;
103	call highmemsize
104	;
105	; Construct the command line (append options have already been copied)
106	;
107	construct_cmdline:
108	mov di,[CmdLinePtr]
109	mov si,boot_image ; BOOT_IMAGE=
110	mov cx,boot_image_len
111	rep movsb
112	mov si,KernelCName ; Unmangled kernel name
113	mov cx,[KernelCNameLen]
114	rep movsb
115	mov al,' ' ; Space
116	stosb
117
118	SPECIAL_APPEND ; Module-specific hook
119
120	mov si,[CmdOptPtr] ; Options from user input
121	call strcpy
122
123	;
124	; Scan through the command line for anything that looks like we might be
125	; interested in. The original version of this code automatically assumed
126	; the first option was BOOT_IMAGE=, but that is no longer certain.
127	;
128	mov si,cmd_line_here
129	xor ax,ax
130	mov [InitRDPtr],ax ; No initrd= option (yet)
131	push es ; Set DS <- real_mode_seg
132	pop ds
133	get_next_opt: lodsb
134	and al,al
135	jz cmdline_end
136	cmp al,' '
137	jbe get_next_opt
138	dec si
139	mov eax,[si]
140	cmp eax,'vga='
141	je is_vga_cmd
142	cmp eax,'mem='
143	je is_mem_cmd
144	%if IS_PXELINUX
145	cmp eax,'keep' ; Is it "keeppxe"?
146	jne .notkeep
147	cmp dword [si+3],'ppxe'
148	jne .notkeep
149	cmp byte [si+7],' ' ; Must be whitespace or EOS
150	ja .notkeep
151	or byte [cs:KeepPXE],1
152	.notkeep:
153	%endif
154	push es ; Save ES -> real_mode_seg
155	push cs
156	pop es ; Set ES <- normal DS
157	mov di,initrd_cmd
158	mov cx,initrd_cmd_len
159	repe cmpsb
160	jne .not_initrd
161
162	cmp al,' '
163	jbe .noramdisk
164	mov [cs:InitRDPtr],si
165	jmp .not_initrd
166	.noramdisk:
167	xor ax,ax
168	mov [cs:InitRDPtr],ax
169	.not_initrd: pop es ; Restore ES -> real_mode_seg
170	skip_this_opt: lodsb ; Load from command line
171	cmp al,' '
172	ja skip_this_opt
173	dec si
174	jmp short get_next_opt
175	is_vga_cmd:
176	add si,4
177	mov eax,[si-1]
178	mov bx,-1
179	cmp eax,'=nor' ; vga=normal
180	je vc0
181	dec bx ; bx <- -2
182	cmp eax,'=ext' ; vga=ext
183	je vc0
184	dec bx ; bx <- -3
185	cmp eax,'=ask' ; vga=ask
186	je vc0
187	call parseint ; vga=<number>
188	jc skip_this_opt ; Not an integer
189	vc0: mov [bs_vidmode],bx ; Set video mode
190	jmp short skip_this_opt
191	is_mem_cmd:
192	add si,4
193	call parseint
194	jc skip_this_opt ; Not an integer
195	%if HIGHMEM_SLOP != 0
196	sub ebx,HIGHMEM_SLOP
197	%endif
198	mov [cs:HighMemSize],ebx
199	jmp short skip_this_opt
200	cmdline_end:
201	push cs ; Restore standard DS
202	pop ds
203	sub si,cmd_line_here
204	mov [CmdLineLen],si ; Length including final null
205	;
206	; Now check if we have a large kernel, which needs to be loaded high
207	;
208	mov dword [RamdiskMax], HIGHMEM_MAX ; Default initrd limit
209	cmp dword [es:su_header],HEADER_ID ; New setup code ID
210	jne old_kernel ; Old kernel, load low
211	cmp word [es:su_version],0200h ; Setup code version 2.0
212	jb old_kernel ; Old kernel, load low
213	cmp word [es:su_version],0201h ; Version 2.01+?
214	jb new_kernel ; If 2.00, skip this step
215	mov word [es:su_heapend],linux_stack ; Set up the heap
216	or byte [es:su_loadflags],80h ; Let the kernel know we care
217	cmp word [es:su_version],0203h ; Version 2.03+?
218	jb new_kernel ; Not 2.03+
219	mov eax,[es:su_ramdisk_max]
220	mov [RamdiskMax],eax ; Set the ramdisk limit
221
222	;
223	; We definitely have a new-style kernel. Let the kernel know who we are,
224	; and that we are clueful
225	;
226	new_kernel:
227	mov byte [es:su_loader],my_id ; Show some ID
228	movzx ax,byte [es:bs_setupsecs] ; Variable # of setup sectors
229	mov [SetupSecs],ax
230	xor eax,eax
231	mov [es:su_ramdisklen],eax ; No initrd loaded yet
232
233	;
234	; About to load the kernel. This is a modern kernel, so use the boot flags
235	; we were provided.
236	;
237	mov al,[es:su_loadflags]
238	mov [LoadFlags],al
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	mov si,KernelCName ; Print kernel name part of
246	call cwritestr ; "Loading" message
247	mov si,dotdot_msg ; Print dots
248	call cwritestr
249
250	mov eax,[HighMemSize]
251	sub eax,100000h ; Load address
252	cmp eax,[KernelSize]
253	jb no_high_mem ; Not enough high memory
254	;
255	; Move the stuff beyond the setup code to high memory at 100000h
256	;
257	movzx esi,word [SetupSecs] ; Setup sectors
258	inc si ; plus 1 boot sector
259	shl si,9 ; Convert to bytes
260	mov ecx,8000h ; 32K
261	sub ecx,esi ; Number of bytes to copy
262	push ecx
263	add esi,(real_mode_seg << 4) ; Pointer to source
264	mov edi,100000h ; Copy to address 100000h
265
266	call bcopy ; Transfer to high memory
267
268	; On exit EDI -> where to load the rest
269
270	mov si,dot_msg ; Progress report
271	call cwritestr
272	call abort_check
273
274	pop ecx ; Number of bytes in the initial portion
275	pop si ; Restore file handle/cluster pointer
276	mov eax,[KernelSize]
277	sub eax,8000h ; Amount of kernel not yet loaded
278	jbe high_load_done ; Zero left (tiny kernel)
279
280	xor dx,dx ; No padding needed
281	call load_high ; Copy the file
282
283	high_load_done:
284	mov [KernelEnd],edi
285	mov ax,real_mode_seg ; Set to real mode seg
286	mov es,ax
287
288	mov si,dot_msg
289	call cwritestr
290
291	;
292	; Now see if we have an initial RAMdisk; if so, do requisite computation
293	; We know we have a new kernel; the old_kernel code already will have objected
294	; if we tried to load initrd using an old kernel
295	;
296	load_initrd:
297	cmp word [InitRDPtr],0
298	jz nk_noinitrd
299	call parse_load_initrd
300	nk_noinitrd:
301	;
302	; Abandon hope, ye that enter here! We do no longer permit aborts.
303	;
304	call abort_check ; Last chance!!
305
306	mov si,ready_msg
307	call cwritestr
308
309	call vgaclearmode ; We can't trust ourselves after this
310
311	UNLOAD_PREP ; Module-specific hook
312
313	;
314	; Now, if we were supposed to load "low", copy the kernel down to 10000h
315	; and the real mode stuff to 90000h. We assume that all bzImage kernels are
316	; capable of starting their setup from a different address.
317	;
318	mov ax,real_mode_seg
319	mov fs,ax
320
321	;
322	; Copy command line. Unfortunately, the kernel boot protocol requires
323	; the command line to exist in the 9xxxxh range even if the rest of the
324	; setup doesn't.
325	;
326	cli ; In case of hooked interrupts
327	test byte [LoadFlags],LOAD_HIGH
328	jz need_high_cmdline
329	cmp word [fs:su_version],0202h ; Support new cmdline protocol?
330	jb need_high_cmdline
331	; New cmdline protocol
332	; Store 32-bit (flat) pointer to command line
333	mov dword [fs:su_cmd_line_ptr],(real_mode_seg << 4) + cmd_line_here
334	jmp short in_proper_place
335
336	need_high_cmdline:
337	;
338	; Copy command line up to 90000h
339	;
340	mov ax,9000h ; Note AL <- 0
341	mov es,ax
342	mov si,cmd_line_here
343	mov di,si
344	mov [fs:kern_cmd_magic],word CMD_MAGIC ; Store magic
345	mov [fs:kern_cmd_offset],di ; Store pointer
346
347	mov cx,[CmdLineLen]
348	cmp cx,255
349	jna .len_ok
350	mov cx,255 ; Protocol < 0x202 has 255 as hard limit
351	.len_ok:
352	fs rep movsb
353	stosb ; Final null, note AL == 0 already
354
355	push fs
356	pop es
357
358	test byte [LoadFlags],LOAD_HIGH
359	jnz in_proper_place ; If high load, we're done
360
361	;
362	; Loading low; we can't assume it's safe to run in place.
363	;
364	; Copy real_mode stuff up to 90000h
365	;
366	mov ax,9000h
367	mov es,ax
368	mov cx,[SetupSecs]
369	inc cx ; Setup + boot sector
370	shl cx,7 ; Sectors -> dwords
371	xor si,si
372	xor di,di
373	fs rep movsd ; Copy setup + boot sector
374	;
375	; Some kernels in the 1.2 ballpark but pre-bzImage have more than 4
376	; setup sectors, but the boot protocol had not yet been defined. They
377	; rely on a signature to figure out if they need to copy stuff from
378	; the "protected mode" kernel area. Unfortunately, we used that area
379	; as a transfer buffer, so it's going to find the signature there.
380	; Hence, zero the low 32K beyond the setup area.
381	;
382	mov di,[SetupSecs]
383	inc di ; Setup + boot sector
384	mov cx,32768/512 ; Sectors/32K
385	sub cx,di ; Remaining sectors
386	shl di,9 ; Sectors -> bytes
387	shl cx,7 ; Sectors -> dwords
388	xor eax,eax
389	rep stosd ; Clear region
390	;
391	; Copy the kernel down to the "low" location
392	;
393	mov ecx,[KernelSize]
394	mov esi,100000h
395	mov edi,10000h
396	call bcopy
397
398	;
399	; Now everything is where it needs to be...
400	;
401	; When we get here, es points to the final segment, either
402	; 9000h or real_mode_seg
403	;
404	in_proper_place:
405
406	;
407	; If the default root device is set to FLOPPY (0000h), change to
408	; /dev/fd0 (0200h)
409	;
410	cmp word [es:bs_rootdev],byte 0
411	jne root_not_floppy
412	mov word [es:bs_rootdev],0200h
413	root_not_floppy:
414
415	;
416	; Copy the disk table to high memory, then re-initialize the floppy
417	; controller
418	;
419	%if IS_SYSLINUX \|\| IS_MDSLINUX
420	lgs si,[cs:fdctab]
421	mov di,linux_fdctab
422	mov cx,6 ; 12 bytes
423	gs rep movsw
424	mov [cs:fdctab],word linux_fdctab ; Save new floppy tab pos
425	mov [cs:fdctab+2],es
426	%endif
427	;
428	; Linux wants the floppy motor shut off before starting the kernel,
429	; at least bootsect.S seems to imply so.
430	;
431	kill_motor:
432	xor ax,ax
433	xor dx,dx
434	int 13h
435
436	;
437	; If we're debugging, wait for a keypress so we can read any debug messages
438	;
439	%ifdef debug
440	xor ax,ax
441	int 16h
442	%endif
443	;
444	; Set up segment registers and the Linux real-mode stack
445	; Note: es == the real mode segment
446	;
447	cli
448	mov bx,es
449	mov ds,bx
450	mov fs,bx
451	mov gs,bx
452	mov ss,bx
453	mov sp,linux_stack
454	;
455	; We're done... now RUN THAT KERNEL!!!!
456	; Setup segment == real mode segment + 020h; we need to jump to offset
457	; zero in the real mode segment.
458	;
459	add bx,020h
460	push bx
461	push word 0h
462	retf
463
464	;
465	; Load an older kernel. Older kernels always have 4 setup sectors, can't have
466	; initrd, and are always loaded low.
467	;
468	old_kernel:
469	cmp word [InitRDPtr],0 ; Old kernel can't have initrd
470	je load_old_kernel
471	mov si,err_oldkernel
472	jmp abort_load
473	load_old_kernel:
474	mov word [SetupSecs],4 ; Always 4 setup sectors
475	mov byte [LoadFlags],0 ; Always low
476	jmp read_kernel
477
478	;
479	; parse_load_initrd
480	;
481	; Parse an initrd= option and load the initrds. Note that we load
482	; from the high end of memory first, so we parse this option from
483	; left to right.
484	;
485	parse_load_initrd:
486	push es
487	push ds
488	mov ax,real_mode_seg
489	mov ds,ax
490	push cs
491	pop es ; DS == real_mode_seg, ES == CS
492
493	mov si,[cs:InitRDPtr]
494	.find_end:
495	lodsb
496	cmp al,' '
497	ja .find_end
498	; Now SI points to one character beyond the
499	; byte that ended this option.
500
501	.get_chunk:
502	dec si
503
504	; DS:SI points to a termination byte
505
506	xor ax,ax
507	xchg al,[si] ; Zero-terminate
508	push si ; Save ending byte address
509	push ax ; Save ending byte
510
511	.find_start:
512	dec si
513	cmp si,[cs:InitRDPtr]
514	je .got_start
515	cmp byte [si],','
516	jne .find_start
517
518	; It's a comma byte
519	inc si
520
521	.got_start:
522	push si
523	mov di,InitRD ; Target buffer for mangled name
524	call mangle_name
525	call loadinitrd
526	pop si
527
528	pop ax
529	pop di
530	mov [di],al ; Restore ending byte
531
532	cmp si,[cs:InitRDPtr]
533	ja .get_chunk
534
535	pop ds
536	pop es
537	ret
538
539	;
540	; Load RAM disk into high memory
541	;
542	; Input: InitRD - set to the mangled name of the initrd
543	;
544	loadinitrd:
545	push ds
546	push es
547	mov ax,cs ; CS == DS == ES
548	mov ds,ax
549	mov es,ax
550	mov si,InitRD
551	mov di,InitRDCName
552	call unmangle_name ; Create human-readable name
553	sub di,InitRDCName
554	mov [InitRDCNameLen],di
555	mov di,InitRD
556	call searchdir ; Look for it in directory
557	jz .notthere
558
559	mov cx,dx
560	shl ecx,16
561	mov cx,ax ; ECX <- ram disk length
562
563	mov ax,real_mode_seg
564	mov es,ax
565
566	push ecx ; Bytes to load
567	cmp dword [es:su_ramdisklen],0
568	je .nopadding ; Don't pad the last initrd
569	add ecx,4095
570	and cx,0F000h
571	.nopadding:
572	add [es:su_ramdisklen],ecx
573	mov edx,[HighMemSize] ; End of memory
574	dec edx
575	mov eax,[RamdiskMax] ; Highest address allowed by kernel
576	cmp edx,eax
577	jna .memsize_ok
578	mov edx,eax ; Adjust to fit inside limit
579	.memsize_ok:
580	inc edx
581	and dx,0F000h ; Round down to 4K boundary
582	sub edx,ecx ; Subtract size of ramdisk
583	and dx,0F000h ; Round down to 4K boundary
584	cmp edx,[KernelEnd] ; Are we hitting the kernel image?
585	jb no_high_mem
586
587	mov [es:su_ramdiskat],edx ; Load address
588	mov [RamdiskMax],edx ; Next initrd loaded here
589
590	mov edi,edx ; initrd load address
591	push si
592	mov si,crlfloading_msg ; Write "Loading "
593	call cwritestr
594	mov si,InitRDCName ; Write ramdisk name
595	call cwritestr
596	mov si,dotdot_msg ; Write dots
597	call cwritestr
598	pop si
599
600	pop eax ; Bytes to load
601	mov dx,0FFFh ; Pad to page
602	call load_high ; Load the file
603
604	pop es
605	pop ds
606	jmp crlf ; Print carriage return and return
607
608	.notthere:
609	mov si,err_noinitrd
610	call cwritestr
611	mov si,InitRDCName
612	call cwritestr
613	mov si,crlf_msg
614	jmp abort_load
615
616	no_high_mem: ; Error routine
617	mov si,err_nohighmem
618	jmp abort_load
619
620	ret
621
622	section .data
623	boot_image db 'BOOT_IMAGE='
624	boot_image_len equ $-boot_image
625
626	section .bss
627	alignb 4
628	RamdiskMax resd 1 ; Highest address for ramdisk
629	KernelSize resd 1 ; Size of kernel in bytes
630	KernelSects resd 1 ; Size of kernel in sectors
631	KernelEnd resd 1 ; Ending address of the kernel image
632	CmdLineLen resw 1 ; Length of command line including null
633	SetupSecs resw 1 ; Number of setup sectors
634	InitRDPtr resw 1 ; Pointer to initrd= option in command line
635	LoadFlags resb 1 ; Loadflags from kernel