comboot.inc

linux内核

;
; INT 22h AX=0006h	Open file
;
comapi_open:
		push ds
		mov ds,P_ES
		mov si,P_SI
		mov di,InitRD
		push di
		call mangle_name
		pop di
		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:
		; Do nothing for now.  Eventually implement
		; an internal API for this.
		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_SYSLINUX || IS_MDSLINUX || IS_EXTLINUX
		mov al,[DriveNumber]
		mov P_DL,al
		mov P_ES,cs
		mov P_BX,PartInfo
%elif 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
%elif IS_ISOLINUX
		mov al,[DriveNo]
		mov P_DL,al
		mov P_ES,cs
		mov P_BX,spec_packet
%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
		ret
%else
comapi_dnsresolv equ comapi_err
%endif
		
		section .text

;
; INT 22h AX=0011h	Maximum number of shuffle descriptors
;
comapi_maxshuffle:
		mov P_CX,(2*trackbufsize)/12
		ret

;
; INT 22h AX=0012h	Cleanup, shuffle and boot
;
comapi_shuffle:
		call comapi_cleanup
		mov cx,P_CX
		cmp cx,(2*trackbufsize)/12
		ja .error

		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:
		push ds
		mov ds,P_DS
		mov si,P_SI
		mov di,KernelName
		push di
		call mangle_name
		pop di
		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

		xor ax,ax
		mov bx,.finish
		jmp comboot_exit_special

.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

		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
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)