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;; -----------------------------------------------------------------------
;;
;; Copyright 1994-2008 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.
;;
;; -----------------------------------------------------------------------
;;
;; comboot.inc
;;
;; Common code for running a COMBOOT image
;;
section .text
; Parameter registers definition; this is the definition
; of the stack frame used by INT 21h and INT 22h.
%define P_FLAGS word [bp+44]
%define P_FLAGSL byte [bp+44]
%define P_FLAGSH byte [bp+45]
%define P_CS word [bp+42]
%define P_IP word [bp+40]
%define P_DS word [bp+38]
%define P_ES word [bp+36]
%define P_FS word [bp+34]
%define P_GS word [bp+32]
%define P_EAX dword [bp+28]
%define P_AX word [bp+28]
%define P_HAX word [bp+30]
%define P_AL byte [bp+28]
%define P_AH byte [bp+29]
%define P_ECX dword [bp+24]
%define P_CX word [bp+24]
%define P_HCX word [bp+26]
%define P_CL byte [bp+24]
%define P_CH byte [bp+25]
%define P_EDX dword [bp+20]
%define P_DX word [bp+20]
%define P_HDX word [bp+22]
%define P_DL byte [bp+20]
%define P_DH byte [bp+21]
%define P_EBX dword [bp+16]
%define P_BX word [bp+16]
%define P_HBX word [bp+18]
%define P_BL byte [bp+16]
%define P_BH byte [bp+17]
%define P_EBP dword [bp+8]
%define P_BP word [bp+8]
%define P_HBP word [bp+10]
%define P_ESI dword [bp+4]
%define P_SI word [bp+4]
%define P_HSI word [bp+6]
%define P_EDI dword [bp]
%define P_DI word [bp]
%define P_HDI word [bp+2]
; Looks like a COMBOOT image but too large
comboot_too_large:
mov si,err_comlarge
call cwritestr
jmp enter_command
;
; Load a COMBOOT image. A COMBOOT image is basically a DOS .COM file,
; except that it may, of course, not contain any DOS system calls. We
; do, however, allow the execution of INT 20h to return to SYSLINUX.
;
is_comboot_image:
and dx,dx
jnz comboot_too_large
cmp ax,0ff00h ; Max size in bytes
jae comboot_too_large
push si ; Save file handle
call make_plain_cmdline
call comboot_setup_api
mov cx,comboot_seg
mov es,cx
xor di,di
mov cx,64 ; 256 bytes (size of PSP)
xor eax,eax ; Clear PSP
rep stosd
mov word [es:0], 020CDh ; INT 20h instruction
; First non-free paragraph
; This is valid because comboot_seg == real_mode_seg
; == the highest segment used by all derivatives
int 12h ; Get DOS memory size
shl ax,6 ; Kilobytes -> paragraphs
mov word [es:02h],ax
%ifndef DEPEND
%if real_mode_seg != comboot_seg
%error "This code assumes real_mode_seg == comboot_seg"
%endif
%endif
; Copy the command line from high memory
mov si,cmd_line_here
mov cx,125 ; Max cmdline len (minus space and CR)
mov di,081h ; Offset in PSP for command line
mov al,' ' ; DOS command lines begin with a space
stosb
.loop: es lodsb
and al,al
jz .done
stosb
loop .loop
.done:
mov al,0Dh ; CR after last character
stosb
mov ax,di
sub al,82h ; Include space but not CR
mov [es:80h],al ; Store command line length
; Now actually load the file...
pop si ; File handle
mov bx,100h ; Load at <seg>:0100h
mov cx,0FF00h >> SECTOR_SHIFT
; Absolute maximum # of sectors
call getfssec
; And invoke the program...
mov ax,es
mov ds,ax
mov ss,ax
xor sp,sp
push word 0 ; Return to address 0 -> exit
jmp comboot_seg:100h ; Run it
; Proper return vector
comboot_return: cli ; Don't trust anyone
push enter_command ; Normal return to command prompt
jmp comboot_exit
;
; Set up the COMBOOT API interrupt vectors. This is also used
; by the COM32 code.
;
comboot_setup_api:
mov di,4*0x20 ; DOS interrupt vectors
mov eax,comboot_return ; INT 20h = exit
stosd
mov ax,comboot_int21 ; INT 21h = DOS-compatible syscalls
stosd
mov ax,comboot_int22 ; INT 22h = proprietary syscalls
stosd
mov ax,comboot_bogus
mov cx,29 ; All remaining DOS vectors
rep stosd
ret
; INT 21h: generic DOS system call
comboot_int21: cli
push ds
push es
push fs
push gs
pushad
cld
mov bp,cs
mov ds,bp
mov es,bp
mov bp,sp ; Set up stack frame
call adjust_screen ; The COMBOOT program might have changed the screen
mov cx,int21_count
mov si,int21_table
.again: lodsb
cmp al,P_AH
lodsw
loopne .again
; The last function in the list is the
; "no such function" function
clc
call ax ; Call the invoked function
comboot_resume:
mov bp,sp ; In case the function clobbers BP
setc P_FLAGSL ; Propagate CF->error
popad
pop gs
pop fs
pop es
pop ds
iret
; Attempted to execute non-21h DOS system call
comboot_bogus: cli ; Don't trust anyone
mov cx,err_notdos
push enter_command
jmp comboot_exit_msg
;
; Generic COMBOOT return to command line code
; stack -> where to go next
; CX -> message (for _msg version)
;
comboot_exit:
xor cx,cx
comboot_exit_msg:
pop bx ; Return address
RESET_STACK_AND_SEGS AX
call adjust_screen ; The COMBOOT program might have changed the screen
jcxz .nomsg
mov si,KernelCName
call cwritestr
mov si,cx
call cwritestr
.nomsg:
jmp bx
;
; INT 21h system calls
;
comboot_getkey: ; 01 = get key with echo
call vgashowcursor
call comboot_getchar
call vgahidecursor
call writechr
clc
ret
comboot_writechr: ; 02 = writechr
mov al,P_DL
call writechr
clc
ret
comboot_writeserial: ; 04 = write serial port
mov al,P_DL
call write_serial
clc
ret
comboot_getkeynoecho: ; 08 = get key w/o echo
call comboot_getchar
clc
ret
comboot_writestr: ; 09 = write DOS string
mov es,P_DS
mov si,P_DX
.loop: es lodsb
cmp al,'$' ; End string with $ - bizarre
je .done
call writechr
jmp short .loop
.done: clc
ret
comboot_checkkey: ; 0B = check keyboard status
cmp byte [APIKeyFlag],00h
jnz .waiting
call pollchar
.waiting: setz al
dec al ; AL = 0FFh if present, 0 if not
mov P_AL,al
clc
ret
comboot_checkver: ; 30 = check DOS version
; We return 0 in all DOS-compatible version registers,
; but the high part of eax-ebx-ecx-edx spell "SYSLINUX"
mov P_EAX,'SY' << 16
mov P_EBX,'SL' << 16
mov P_ECX,'IN' << 16
mov P_EDX,'UX' << 16
ret
comboot_getchar:
cmp byte [APIKeyFlag],00h
jne .queued
call getchar ; If not queued get input
and al,al ; Function key? (CF <- 0)
jnz .done
mov [APIKeyWait],ah ; High part of key
inc byte [APIKeyFlag] ; Set flag
.done: mov P_AL,al
ret
.queued: mov al,[APIKeyWait]
dec byte [APIKeyFlag]
jmp .done
;
; INT 22h - SYSLINUX-specific system calls
; System call number in ax
;
comboot_int22:
cli
push ds
push es
push fs
push gs
pushad
cld
mov bp,cs
mov ds,bp
mov es,bp
mov bp,sp ; Set up stack frame
call adjust_screen ; The COMBOOT program might have changed the screen
cmp ax,int22_count
jb .ok
xor ax,ax ; Function 0 -> unimplemented
.ok:
xchg ax,bx
add bx,bx ; CF <- 0
call [bx+int22_table]
jmp comboot_resume ; On return
;
; INT 22h AX=0000h Unimplemented call
;
comapi_err:
stc
ret
;
; INT 22h AX=0001h Get SYSLINUX version
;
comapi_get_version:
; Number of API functions supported
mov P_AX,int22_count
; SYSLINUX version
mov P_CX,(VER_MAJOR << 8)+VER_MINOR
; SYSLINUX derivative ID byte
mov P_DX,my_id
; For future use
mov P_BX,cs ; cs == 0
mov P_ES,ds
; ES:SI -> version banner
mov P_SI,syslinux_banner
; ES:DI -> copyright string
mov P_DI,copyright_str
comapi_nop:
clc
ret
;
; INT 22h AX=0002h Write string
;
; Write null-terminated string in ES:BX
;
comapi_writestr:
mov ds,P_ES
mov si,P_BX
call writestr
clc
ret
;
; INT 22h AX=0003h Run command
;
; Terminates the COMBOOT program and executes the command line in
; ES:BX as if it had been entered by the user.
;
comapi_run:
mov ds,P_ES
mov si,P_BX
mov di,command_line
call strcpy
push load_kernel ; Run a new kernel
jmp comboot_exit ; Terminate task, clean up
;
; INT 22h AX=0004h Run default command
;
; Terminates the COMBOOT program and executes the default command line
; as if a timeout had happened or the user pressed <Enter>.
;
comapi_run_default:
push auto_boot
jmp comboot_exit
;
; INT 22h AX=0005h Force text mode
;
; Puts the video in standard text mode
;
comapi_textmode:
call vgaclearmode
clc
ret
;
; INT 22h AX=0006h Open file
;
comapi_open:
push ds
mov ds,P_ES
mov si,P_SI
mov di,InitRD
call mangle_name
pop ds
call searchdir
jz comapi_err
mov P_AX,ax
mov P_HAX,dx
mov P_CX,SECTOR_SIZE
mov P_SI,si
clc
ret
;
; INT 22h AX=0007h Read file
;
comapi_read:
mov es,P_ES
mov bx,P_BX
mov si,P_SI
mov cx,P_CX
call getfssec
jnc .noteof
xor si,si ; SI <- 0 on EOF, CF <- 0
.noteof: mov P_SI,si
ret
;
; INT 22h AX=0008h Close file
;
comapi_close:
mov si,P_SI
call close_file
clc
ret
;
; INT 22h AX=0009h Call PXE stack
;
%if IS_PXELINUX
comapi_pxecall:
mov bx,P_BX
mov es,P_ES
mov di,P_DI
call pxenv
mov P_AX,ax
clc
ret
%else
comapi_pxecall equ comapi_err ; Not available
%endif
;
; INT 22h AX=000Ah Get Derivative-Specific Info
;
comapi_derinfo:
mov P_AL,my_id
%if IS_PXELINUX
mov ax,[APIVer]
mov P_DX,ax
mov ax,[StrucPtr]
mov P_BX,ax
mov ax,[StrucPtr+2]
mov P_ES,ax
mov ax,[InitStack]
mov P_SI,ax
mov ax,[InitStack+2]
mov P_FS,ax
%else
; Physical medium...
mov P_CL,SECTOR_SHIFT
mov al,[DriveNumber]
mov P_DL,al
mov P_FS,cs
mov P_SI,OrigESDI
%if IS_SYSLINUX || IS_MDSLINUX || IS_EXTLINUX
mov P_ES,cs
mov P_BX,PartInfo
%elif IS_ISOLINUX
mov P_ES,cs
mov P_BX,spec_packet
%endif
%endif
clc
ret
;
; INT 22h AX=000Bh Get Serial Console Configuration
;
comapi_serialcfg:
mov ax,[SerialPort]
mov P_DX,ax
mov ax,[BaudDivisor]
mov P_CX,ax
mov ax,[FlowControl]
or al,ah
mov ah,[FlowIgnore]
shr ah,4
test byte [DisplayCon],01h
jnz .normalconsole
or ah,80h
.normalconsole:
mov P_BX,ax
clc
ret
;
; INT 22h AX=000Ch Perform final cleanup
;
comapi_cleanup:
%if IS_PXELINUX
; Unload PXE if requested
test dl,3
setnz [KeepPXE]
sub bp,sp ; unload_pxe may move the stack around
call unload_pxe
add bp,sp ; restore frame pointer...
%elif IS_SYSLINUX || IS_MDSLINUX || IS_EXTLINUX
; Restore original FDC table
mov eax,[OrigFDCTabPtr]
mov [fdctab],eax
%endif
; Reset the floppy disk subsystem
xor ax,ax
xor dx,dx
int 13h
clc
ret
;
; INT 22h AX=000Dh Clean up then replace bootstrap
;
comapi_chainboot:
call comapi_cleanup
mov eax,P_EDI
mov [trackbuf+4],eax ; Copy from
mov eax,P_ECX
mov [trackbuf+8],eax ; Total bytes
mov eax,7C00h
mov [trackbuf],eax ; Copy to
mov [EntryPoint],eax ; CS:IP entry point
mov esi,P_ESI
mov edx,P_EBX
mov bx,P_DS
jmp replace_bootstrap_one
;
; INT 22h AX=000Eh Get configuration file name
;
comapi_configfile:
mov P_ES,cs
mov P_BX,ConfigName
clc
ret
;
; INT 22h AX=000Fh Get IPAPPEND strings
;
%if IS_PXELINUX
comapi_ipappend:
mov P_ES,cs
mov P_CX,numIPAppends
mov P_BX,IPAppends
clc
ret
section .data
alignb 2, db 0
IPAppends dw IPOption
dw BOOTIFStr
numIPAppends equ ($-IPAppends)/2
%else
comapi_ipappend equ comapi_err
%endif
section .text
;
; INT 22h AX=0010h Resolve hostname
;
%if IS_PXELINUX
comapi_dnsresolv:
mov ds,P_ES
mov si,P_BX
call dns_resolv
mov P_EAX,eax
clc
ret
%else
comapi_dnsresolv equ comapi_err
%endif
section .text
;
; INT 22h AX=0011h Maximum number of shuffle descriptors
;
comapi_maxshuffle:
mov P_CX,trackbufsize/12
ret
;
; INT 22h AX=0012h Cleanup, shuffle and boot
;
comapi_shuffle:
cmp P_CX,(2*trackbufsize)/12
ja .error
call comapi_cleanup
mov cx, P_CX
push cx ; On stack: descriptor count
lea cx,[ecx+ecx*2] ; CX *= 3
mov fs,P_ES
mov si,P_DI
mov di,trackbuf
push di ; On stack: descriptor list address
fs rep movsd ; Copy the list
mov eax,P_EBP
mov [EntryPoint],eax ; CS:IP entry point
mov esi,P_ESI
mov edx,P_EBX
mov bx,P_DS
jmp replace_bootstrap
.error:
stc
ret
;
; INT 22h AX=0013h Idle call
;
;
; *** FIX THIS ***
; The idle call seems to have detrimental effects on some machines when
; called from a COM32 context (WHY?) -- disable it for now.
;
%if 0 ; def HAVE_IDLE
comapi_idle:
DO_IDLE
clc
ret
%else
comapi_idle equ comapi_err
%endif
;
; INT 22h AX=0014h Local boot
;
%if IS_PXELINUX || IS_ISOLINUX
comapi_localboot:
mov ax,P_DX
jmp local_boot
%else
comapi_localboot equ comapi_err
%endif
;
; INT 22h AX=0015h Feature flags
;
comapi_features:
mov P_ES,cs
mov P_BX,feature_flags
mov P_CX,feature_flags_len
clc
ret
;
; INT 22h AX=0016h Run kernel image
;
comapi_runkernel:
mov al,P_DL
cmp al,VK_TYPES-1
ja .error
mov [KernelType],al
push ds
mov ds,P_DS
mov si,P_SI
mov di,KernelName
call mangle_name
pop ds
call searchdir
jz comapi_err
; The kernel image was found, so we can load it...
mov [Kernel_SI],si
mov [Kernel_EAX],ax
mov [Kernel_EAX+2],dx
; It's not just possible, but quite likely, that ES:BX
; points into real_mode_seg, so we need to exercise some
; special care here... use xfer_buf_seg as an intermediary
push ds
push es
mov ax,xfer_buf_seg
mov ds,P_ES
mov si,P_BX
mov es,ax
xor di,di
call strcpy
pop es
pop ds
%if IS_PXELINUX
mov al,P_CL
mov [IPAppend],al
%endif
call comboot_exit
.finish:
; Copy the command line into its proper place
push ds
push es
mov ax,xfer_buf_seg
mov dx,real_mode_seg
mov ds,ax
mov es,dx
xor si,si
mov di,cmd_line_here
call strcpy
mov byte [es:di-1],' ' ; Simulate APPEND
pop es
pop ds
mov [CmdLinePtr],di
mov word [CmdOptPtr],zero_string
jmp kernel_good_saved
.error equ comapi_shuffle.error
;
; INT 22h AX=0017h Report video mode change
;
comapi_usingvga:
mov ax,P_BX
cmp ax,0Fh ; Unknown flags = failure
ja .error
mov [UsingVGA],al
mov cx,P_CX
mov dx,P_DX
mov [GXPixCols],cx
mov [GXPixRows],dx
test al,08h
jnz .notext
call adjust_screen
.notext:
clc
ret
.error:
stc
ret
;
; INT 22h AX=0018h Query custom font
;
comapi_userfont:
mov al,[UserFont]
and al,al
jz .done
mov al,[VGAFontSize]
mov P_ES,ds
mov P_BX,vgafontbuf
.done: ; CF=0 here
mov P_AL,al
ret
;
; INT 22h AX=0019h Read disk
;
%if IS_SYSLINUX || IS_MDSLINUX || IS_ISOLINUX || IS_EXTLINUX
comapi_readdisk:
mov esi,P_ESI ; Enforce ESI == EDI == 0, these
or esi,P_EDI ; are reserved for future expansion
jnz .err
mov eax,P_EDX
mov es,P_ES
mov bx,P_BX
mov bp,P_CX ; WE CANNOT use P_* after touching bp!
call getlinsec
clc
ret
.err:
stc
ret
%else
comapi_readdisk equ comapi_err
%endif
;
; INT 22h AX=001Ah Cleanup, shuffle and boot to flat protected mode
;
comapi_shufflepm:
cmp P_CX,(2*trackbufsize)/12
ja .error
call comapi_cleanup
mov cx, P_CX
push cx ; On stack: descriptor count
lea cx,[ecx+ecx*2] ; CX *= 3
mov fs,P_ES
mov si,P_DI
mov di,trackbuf
push di ; On stack: descriptor list address
fs rep movsd ; Copy the list
mov fs,P_DS
mov si,P_SI
mov edi,TrampolineBuf
mov al,0B8h ; MOV EAX opcode
mov cl,9
.maketramp:
stosb ; MOV opcode
inc ax ; Next register opcode
fs movsd ; immediate value
loop .maketramp
mov byte [di-5],0E9h ; Last opcode is JMP
sub [di-4],edi ; Make JMP target relative
mov dword [EntryPoint],trampoline_to_pm
xor bx,bx ; DS on entry
jmp replace_bootstrap
.error:
stc
ret
;
; INT 22h AX=001Bh Cleanup, shuffle and boot with register setting
;
comapi_shufflerm:
cmp P_CX,(2*trackbufsize)/12
ja .error
call comapi_cleanup
mov cx, P_CX
push cx ; On stack: descriptor count
lea cx,[ecx+ecx*2] ; CX *= 3
mov fs,P_ES
mov si,P_DI
mov di,trackbuf
push di ; On stack: descriptor list address
fs rep movsd ; Copy the list
mov fs,P_DS
mov si,P_SI
mov di,TrampolineBuf
; Generate segment-loading instructions
mov bx,0C08Eh ; MOV ES,AX
mov cl,6 ; 6 segment registers (incl CS)
.segtramp:
mov al,0B8h
stosb ; MOV AX,imm16 opcode
fs movsw ; imm16
mov ax,bx
add bh,8
stosw ; MOV xS,AX
loop .segtramp
; Clobber the MOV CS,AX instruction.
mov word [di-22], 9090h ; NOP NOP
; Generate GPR-loading instructions
mov ax,0B866h ; MOV EAX,imm32
mov cl,8 ; 8 GPRs
.gprtramp:
stosw ; MOV ExX,imm32 opcode
fs movsd ; imm32
inc ah
loop .gprtramp
mov al,0EAh ; JMP FAR imm16:imm16 opcode
stosb
fs movsd ; CS:IP
mov dword [EntryPoint],TrampolineBuf
jmp replace_bootstrap
.error:
stc
ret
;
; INT 22h AX=001Ch Get pointer to auxillary data vector
;
comapi_getadv:
mov P_ES,ds
mov P_BX,adv0.data
mov P_CX,ADV_LEN
ret
;
; INT 22h AX=001Dh Write auxillary data vector
;
comapi_writeadv equ adv_write
section .data
%macro int21 2
db %1
dw %2
%endmacro
int21_table:
int21 00h, comboot_return
int21 01h, comboot_getkey
int21 02h, comboot_writechr
int21 04h, comboot_writeserial
int21 08h, comboot_getkeynoecho
int21 09h, comboot_writestr
int21 0Bh, comboot_checkkey
int21 30h, comboot_checkver
int21 4Ch, comboot_return
int21 -1, comboot_bogus
int21_count equ ($-int21_table)/3
align 2, db 0
int22_table:
dw comapi_err ; 0000 unimplemented syscall
dw comapi_get_version ; 0001 get SYSLINUX version
dw comapi_writestr ; 0002 write string
dw comapi_run ; 0003 run specified command
dw comapi_run_default ; 0004 run default command
dw comapi_textmode ; 0005 force text mode
dw comapi_open ; 0006 open file
dw comapi_read ; 0007 read file
dw comapi_close ; 0008 close file
dw comapi_pxecall ; 0009 call PXE stack
dw comapi_derinfo ; 000A derivative-specific info
dw comapi_serialcfg ; 000B get serial port config
dw comapi_cleanup ; 000C perform final cleanup
dw comapi_chainboot ; 000D clean up then bootstrap
dw comapi_configfile ; 000E get name of config file
dw comapi_ipappend ; 000F get ipappend strings
dw comapi_dnsresolv ; 0010 resolve hostname
dw comapi_maxshuffle ; 0011 maximum shuffle descriptors
dw comapi_shuffle ; 0012 cleanup, shuffle and boot
dw comapi_idle ; 0013 idle call
dw comapi_localboot ; 0014 local boot
dw comapi_features ; 0015 feature flags
dw comapi_runkernel ; 0016 run kernel image
dw comapi_usingvga ; 0017 report video mode change
dw comapi_userfont ; 0018 query custom font
dw comapi_readdisk ; 0019 read disk
dw comapi_shufflepm ; 001A cleanup, shuffle and boot to pm
dw comapi_shufflerm ; 001B cleanup, shuffle and boot to rm
dw comapi_getadv ; 001C get pointer to ADV
dw comapi_writeadv ; 001D write ADV to disk
int22_count equ ($-int22_table)/2
APIKeyWait db 0
APIKeyFlag db 0
zero_string db 0 ; Empty, null-terminated string
;
; This is the feature flag array for INT 22h AX=0015h
feature_flags:
%if IS_PXELINUX
db 1 ; Have local boot, idle not noop
%elif IS_ISOLINUX
db 3 ; Have local boot, idle is noop
%else
db 2 ; No local boot, idle is noop
%endif
feature_flags_len equ ($-feature_flags)
err_notdos db ': attempted DOS system call', CR, LF, 0
err_comlarge db 'COMBOOT image too large.', CR, LF, 0
section .bss1
ConfigName resb FILENAME_MAX