comboot.doc

linux内核

	Output:	None

	Close a file before reaching the end of file.

	WARNING: Calling this function with an invalid file handle
	will probably crash the system.


AX=0009h [2.00] Call PXE Stack [PXELINUX ONLY]

	Input:	AX	0009h
		BX	PXE function number
		ES:DI	PXE data buffer
	Output:	AX	PXE return status code

	Invoke an arbitrary PXE stack function.  On SYSLINUX/ISOLINUX,
	this function returns with an error (CF=1) and no action is
	taken.  On PXELINUX, this function always returns with CF=0
	indicating that the PXE stack was successfully invoked; check
	the status code in AX and in the first word of the data buffer
	to determine if the PXE call succeeded or not.

	The PXE stack will have the UDP stack OPEN; if you change that
	you cannot call any of the file-related API functions, and
	must restore UDP OPEN before returning to PXELINUX.

	PXELINUX reserves UDP port numbers from 49152 to 65535 for its
	own use; port numbers below that range is available.


AX=000Ah [2.00]	Get Derivative-Specific Information

	[SYSLINUX, EXTLINUX]
	Input:	AX	000Ah
	Output:	AL	31h (SYSLINUX), 34h (EXTLINUX)
		DL	drive number
		ES:BX	pointer to partition table entry (if DL >= 80h)

		Note: This function was broken in EXTLINUX 3.00-3.02.


	[PXELINUX]
	Input:	AX	000Ah
	Output:	AL	32h (PXELINUX)
		DX	PXE API version detected (DH=major, DL=minor)
		ES:BX	pointer to PXENV+ or !PXE structure
		FS:SI	pointer to original stack with invocation record

		Note: DX notes the API version detected by PXELINUX,
		which may be more conservative than the actual version
		available.  For exact information examine the API
		version entry in the PXENV+ structure, or the API
		version entries in the ROMID structures pointed from
		the !PXE structure.

		PXELINUX will use, and provide, the !PXE structure
		over the PXENV+ structure.  Examine the structure
		signature to determine which particular structure was
		provided.

		The FS:SI pointer points to the top of the original stack
		provided by the PXE stack, with the following values
		pushed at the time PXELINUX is started:

		[fs:si+0]	GS		<- top of stack
		[fs:si+2]	FS
		[fs:si+4]	ES
		[fs:si+6]	DS
		[fs:si+8]	EDI
		[fs:si+12]	ESI
		[fs:si+16]	EBP
		[fs:si+20]	-
		[fs:si+24]	EBX
		[fs:si+28]	EDX
		[fs:si+32]	ECX
		[fs:si+36]	EAX
		[fs:si+40]	EFLAGS
		[fs:si+44]	PXE return IP	<- t.o.s. when PXELINUX invoked
		[fs:si+46]	PXE return CS


	[ISOLINUX]
	Input:	AX	000Ah
	Output:	AL	33h (ISOLINUX)
		DL	drive number
		ES:BX	pointer to El Torito spec packet

		Note: Some very broken El Torito implementations do
		not provide the spec packet information.  If so, ES:BX
		may point to all zeroes or to garbage.  Call INT 13h,
		AX=4B01h to obtain the spec packet directly from the
		BIOS if necessary.

	This call gives information specific to a particular SYSLINUX
	derivative.  The value returned in AL is the same as is
	returned in DL by INT 22h AX=0001h.


AX=000Bh [2.00]	Get Serial Console Configuration

	Input:	AX	000Bh
	Output:	DX	serial port I/O base (e.g. 3F8h = COM1...)
		CX	baud rate divisor (1 = 115200 bps, 2 = 57600 bps...)
		BX	flow control configuration bits (see syslinux.doc)
			-> bit 15 is set if the video console is disabled

	If no serial port is configured, DX will be set to 0 and the
	other registers are undefined.


AX=000Ch [2.00]	Perform final cleanup
	Input:	AX	000Ch
		DX	derivative-specific flags (0000h = clean up all)
	Output:	Does not return

	This routine performs any "final cleanup" the boot loader
	would normally perform before loading a kernel, such as
	unloading the PXE stack in the case of PXELINUX.  AFTER
	INVOKING THIS CALL, NO OTHER API CALLS MAY BE INVOKED, NOR MAY
	THE PROGRAM TERMINATE AND RETURN TO THE BOOT LOADER.  This
	call basically tells the boot loader "get out of the way, I'll
	handle it from here."

	For COM32 images, the boot loader will continue to provide
	interrupt and BIOS call thunking services as long its memory
	areas (0x0800-0xffff, 0x100000-0x100fff) are not overwritten.
	MAKE SURE TO DISABLE INTERRUPTS, AND INSTALL NEW GDT AND IDTS
	BEFORE OVERWRITING THESE MEMORY AREAS.

	The permissible values for DX is an OR of these values:

	SYSLINUX:	0000h	Normal cleanup

	PXELINUX:	0000h	Normal cleanup
			0003h	Keep UNDI and PXE stacks loaded

	ISOLINUX:	0000h	Normal cleanup

	EXTLINUX:	0000h	Normal cleanup

	All other values are undefined, and may have different
	meanings in future versions of SYSLINUX.


AX=000Dh [2.08]	Cleanup and replace bootstrap code
	Input:	AX	000Dh
		DX	derivative-specific flags (see previous function)
		EDI	bootstrap code (linear address, can be in high memory)
		ECX	bootstrap code length in bytes (must fit in low mem)
		EBX(!)	initial value of EDX after bootstrap
		ESI	initial value of ESI after bootstrap
		DS	initial value of DS after bootstrap
	Output:	Does not return

	This routine performs final cleanup, then takes a piece of
	code, copies it over the primary bootstrap at address 7C00h,
	and jumps to it.  This can be used to chainload boot sectors,
	MBRs, bootstraps, etc.

	Normal boot sectors expect DL to contain the drive number,
	and, for hard drives (DL >= 80h) DS:SI to contain a pointer to
	the 16-byte partition table entry.  The memory between
	600h-7FFh is available to put the partition table entry in.

	For PXELINUX, if the PXE stack is not unloaded, all registers
	(except DS, ESI and EDX) and the stack will be set up as they
	were set up by the PXE ROM.


AX=000Eh [2.11]	Get configuration file name
	Input:	AX	0000Eh
	Output:	ES:BX	null-terminated file name string

	Returns the name of the configuration file.  Note that it is
	possible that the configuration file doesn't actually exist.


AX=000Fh [3.00] Get IPAPPEND strings [PXELINUX]
	Input:  AX	000Fh
	Output:	CX	number of strings (currently 2)
		ES:BX	pointer to an array of NEAR pointers in
			the same segment, one for each of the above
			strings

	Returns the same strings that the "ipappend" option would have
	added to the command line, one for each bit of the "ipappend"
	flag value, so entry 0 is the "ip=" string and entry 1 is the
	"BOOTIF=" string.


AX=0010h [3.00] Resolve hostname [PXELINUX]
	Input:  ES:BX	pointer to null-terminated hostname
	Output:	EAX	IP address of hostname (zero if not found)

	Queries the DNS server(s) for a specific hostname.  If the
	hostname does not contain a dot (.), the local domain name
	is automatically appended.

	This function only return CF=1 if the function is not
	supported.  If the function is supported, but the hostname did
	not resolve, it returns with CF=0, EAX=0.

	The IP address is returned in network byte order, i.e. if the
	IP address is 1.2.3.4, EAX will contain 0x04030201.  Note that
	all uses of IP addresses in PXE are also in network byte order.


AX=0011h [3.05] Maximum number of shuffle descriptors
	Input:	AX	0011h
	Output:	CX	maximum number of descriptors

	This routine reports the maximum number of shuffle descriptors
	permitted in a call to function 0012h.

	Typical values are 682 and 1365.


AX=0012h [3.05] Cleanup, shuffle and boot
	Input:	AX	0012h
		DX	derivative-specific flags (see previous function)
		ES:DI	shuffle descriptor list (must be in low memory)
		CX	number of shuffle descriptors
		EBX(!)	initial value of EDX after bootstrap
		ESI	initial value of ESI after bootstrap
		DS	initial value of DS after bootstrap
		EBP	CS:IP of routine to jump to
	Output:	Does not return
		(if CX is too large the routine returns with CF=1)

	This routine performs final cleanup, then performs a sequence
	of copies, and jumps to a specified real mode entry point.
	This is a more general version of function 000Dh, which can
	also be used to load other types of programs.

	The copies must not touch memory below address 7C00h.

	ES:DI points to a list of CX descriptors each of the form:
	
		Offset	Size	Meaning
		 0	dword	destination address
		 4	dword	source address
		 8	dword	length in bytes

	The copies are overlap-safe, like memmove().

	Normal boot sectors expect DL to contain the drive number,
	and, for hard drives (DL >= 80h) DS:SI to contain a pointer to
	the 16-byte partition table entry.  The memory between
	600h-7FFh is available to put the partition table entry in.

	For PXELINUX, if the PXE stack is not unloaded, all registers
	(except DS, ESI and EDX) and the stack will be set up as they
	were set up by the PXE ROM.


AX=0013h [3.08] Idle loop call
	Input:	AX	0013h
	Output:	None

	Call this routine while sitting in an idle loop.  It performs
	any periodic activities required by the filesystem code.  At
	the moment, this is a no-op on all derivatives except
	PXELINUX, where it executes PXE calls to answer ARP queries.

	Starting with version 3.10, this API call harmlessly returns
	failure (CF=1) if invoked on a platform which does not need
	idle calls.  Additionally, it's safe to call this API call on
	previous SYSLINUX versions (2.00 or later); it will just
	harmlessly fail.  Thus, if this call returns failure (CF=1),
	it means that there is no technical reason to call this
	function again, although doing so is of course safe.


AX=0014h [3.10] Local boot [PXELINUX, ISOLINUX]
	Input:	AX	0014h
		DX	Local boot parameter
	Output:	Does not return

	This function invokes the equivalent of the "localboot"
	configuration file option.  The parameter in DX is the same
	parameter as would be entered after "localboot" in the
	configuration file; this parameter is derivative-specific --
	see syslinux.doc for the definition.


AX=0015h [3.10] Get feature flags
	Input:	AX	0015h
	Output:	ES:BX	pointer to flags in memory
		CX	number of flag bytes

	This function reports whether or not this SYSLINUX version and
	derivative supports specific features.  Keep in mind that
	future versions might have more bits; remember to treat any
	bits beyond the end of the array (as defined by the value in
	CX) as zero.

	Currently the following feature flag is defined:

	Byte	Bit	Definition
	----------------------------------------------------
	0	0	Local boot (AX=0014h) supported
		1	Idle loop call (AX=0013h) is a no-op

	All other flags are reserved.


AX=0016h [3.10] Run kernel image
	Input:	AX	0016h
		DS:SI	Filename of kernel image (zero-terminated string)
		ES:BX	Command line (zero-terminated string)
		ECX	IPAPPEND flags [PXELINUX]
		EDX	Reserved - MUST BE ZERO
	Output:	Does not return if successful; returns with CF=1 if
		the kernel image is not found.

	This function is similiar to AX=0003h Run command, except that
	the filename and command line are treated as if specified in a
	KERNEL and APPEND statement of a LABEL statement, which means:

	- The filename has to be exact; no variants are tried;
	- No global APPEND statement is applied;
	- ALLOWOPTIONS and IMPLICIT statements in the configuration
	  file do not apply.  It is therefore important that the
	  COMBOOT module doesn't allow the end user to violate the
	  intent of the administrator.

	Additionally, this function returns with a failure if the file
	doesn't exist, instead of returning to the command line.  (It
	may still return to the command line if the image is somehow
	corrupt, however.)