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Diffstat (limited to 'contrib/syslinux/latest/doc/comboot.txt')
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diff --git a/contrib/syslinux/latest/doc/comboot.txt b/contrib/syslinux/latest/doc/comboot.txt deleted file mode 100644 index 4b4b880..0000000 --- a/contrib/syslinux/latest/doc/comboot.txt +++ /dev/null @@ -1,1012 +0,0 @@ - - COMBOOT and COM32 files - - -Syslinux supports simple standalone programs, using a file format -similar to DOS ".com" files. A 32-bit version, called COM32, is also -provided. A simple API provides access to a limited set of filesystem -and console functions. - - - ++++ COMBOOT file format ++++ - -A COMBOOT file is a raw binary file containing 16-bit code. It should -be linked to run at offset 0x100, and contain no absolute segment -references. It is run in 16-bit real mode. - -A COMBOOT image can be written to be compatible with MS-DOS. Such a -file will usually have extension ".com". A COMBOOT file which is not -compatible with MS-DOS will usually have extension ".cbt". - -Before running the program, Syslinux sets up the following fields in -the Program Segment Prefix (PSP), a structure at offset 0 in the -program segment: - - Offset Size Meaning - 0 word Contains an INT 20h instruction - 2 word Contains the paragraph (16-byte "segment" address) at - the end of memory available to the program. - 128 byte Length of the command line arguments, including the leading - space but not including the final CR character. - 129 127b Command line arguments, starting with a space and ending - with a CR character (ASCII 13). - -The program is allowed to use memory between the PSP paragraph (which -all the CS, DS, ES and SS registers point to at program start) and the -paragraph value given at offset 2. - -On startup, SP is set up to point to the end of the 64K segment, at -0xfffe. Under DOS it is possible for SP to contain a smaller -value if memory is very tight; this is never the case under Syslinux. - -The program should make no assumptions about what segment address it -will be loaded at; instead it should look at the segment registers on -program startup. Both DOS and Syslinux will guarantee CS == DS == ES -== SS on program start; the program should not assume anything about -the values of FS or GS. - -To exit, a program can either execute a near RET (which will jump to -offset 0 which contains an INT 20h instruction, terminating the -program), or execute INT 20h or INT 21h AH=00h or INT 21h AH=4Ch. -If compatiblity with Syslinux 1.xx is desired, use INT 20h. - - - ++++ COM32R file format ++++ - -A COM32R file is a raw binary file containing 32-bit code. It should -be self-relocating, as it will be loaded by the Syslinux core at any -4K aligned address. It will be run in flat-memory 32-bit protected -mode. Under Syslinux, it will be run in CPL 0, however, since it may -be possible to create a COM32 execution engine that would run under -something like Linux DOSEMU, it is recommended that the code does not -assume CPL 0 unless absolutely necessary. - -A COM32R program must start with the byte sequence B8 FE 4C CD 21 (mov -eax,21cd4cfeh) as a magic number. - -The COM32R format replaces the earlier COM32 format, which was linked -to a fixed address (0x101000). - -A COM32R file should have extension ".c32". - -On startup, CS will be set up as a flat 32-bit code segment, and DS == -ES == SS will be set up as the equivalent flat 32-bit data segment. -FS and GS are reserved for future use and are currently initialized to -zero. A COM32R image should not assume any particular values of -segment selectors. - -ESP is set up at the end of available memory and also serves as -notification to the program how much memory is available. - -The following arguments are passed to the program on the stack: - - Address Size Meaning - [ESP] dword Return (termination) address - [ESP+4] dword Number of additional arguments (currently 8) - [ESP+8] dword Pointer to the command line arguments (null-terminated string) - [ESP+12] dword Pointer to INT call helper function - [ESP+16] dword Pointer to low memory bounce buffer - [ESP+20] dword Size of low memory bounce buffer - [ESP+24] dword Pointer to FAR call helper function (new in 2.05) - [ESP+28] dword Pointer to CDECL helper function (new in 3.54) - [ESP+32] dword Amount of memory controlled by the Syslinux core (new in 3.74) - [ESP+36] dword Pointer to the filename of the com32 module (new in 3.86) - [ESP+40] dword Pointer to protected-mode functions (new in 4.00) - -The libcom32 startup code loads this into a structure named __com32, -defined in <com32.h>: - -extern struct com32_sys_args { - uint32_t cs_sysargs; - char *cs_cmdline; - void __cdecl(*cs_intcall)(uint8_t, const com32sys_t *, com32sys_t *); - void *cs_bounce; - uint32_t cs_bounce_size; - void __cdecl(*cs_farcall)(uint32_t, const com32sys_t *, com32sys_t *); - int __cdecl(*cs_cfarcall)(uint32_t, const void *, uint32_t); - uint32_t cs_memsize; - const char *cs_name; - const struct com32_pmapi *cs_pm; -} __com32; - -The intcall helper function can be used to issue BIOS or Syslinux API -calls, and takes the interrupt number as first argument. The second -argument is a pointer to the input register definition, an instance of -the following structure (available in <com32.h>): - -typedef union { - uint32_t l; - uint16_t w[2]; - uint8_t b[4]; -} reg32_t; - -typedef struct { - uint16_t gs; /* Offset 0 */ - uint16_t fs; /* Offset 2 */ - uint16_t es; /* Offset 4 */ - uint16_t ds; /* Offset 6 */ - - reg32_t edi; /* Offset 8 */ - reg32_t esi; /* Offset 12 */ - reg32_t ebp; /* Offset 16 */ - reg32_t _unused_esp; /* Offset 20 */ - reg32_t ebx; /* Offset 24 */ - reg32_t edx; /* Offset 28 */ - reg32_t ecx; /* Offset 32 */ - reg32_t eax; /* Offset 36 */ - - reg32_t eflags; /* Offset 40 */ -} com32sys_t; - -The third argument is a pointer to the output register definition, an -instance of the same structure. The third argument can also be zero -(NULL). - -Since BIOS or Syslinux API calls can generally only manipulate data -below address 0x100000, a "bounce buffer" in low memory, at least 64K -in size, is available, to copy data in and out. - -The farcall helper function behaves similarly, but takes as its first -argument the CS:IP (in the form (CS << 16) + IP) of procedure to be -invoked via a FAR CALL. - -The cfarcall helper function takes (CS << 16)+IP, a pointer to a stack -frame, a size of that stack frame, and returns the return value of EAX -(which may need to be appropriate truncated by the user.) - -Starting in version 4.00, some of these API calls are available as -protected-mode function calls, using the regparm(3) calling convention -(the first three argumetns in EAX, EDX, ECX; the rest on the stack.) -Those functions are defined in struct com32_pmapi, defined in -<syslinux/pmapi.h>. - - - ++++ SYSLINUX API CALLS +++ - -Syslinux provides the following API calls. Syslinux 1.xx only -supported INT 20h - terminate program. [] indicates the first version -of Syslinux which supported this feature (correctly.) - -NOTE: Most of the API functionality is still experimental. Expect to -find bugs. - - - ++++ DOS-COMPATIBLE API CALLS ++++ - -INT 20h [1.48] Terminate program -INT 21h AH=00h [2.00] Terminate program -INT 21h AH=4Ch [2.00] Terminate program - - All of these terminate the program. - - -INT 21h AH=01h [2.01] Get Key with Echo - - Reads a key from the console input, with echo to the console - output. The read character is returned in AL. Extended - characters received from the keyboard are returned as NUL (00h) - + the extended character code. - - -INT 21h AH=02h [2.01] Write Character - - Writes a character in DL to the console (video and serial) - output. - - -INT 21h AH=04h [2.01] Write Character to Serial Port - - Writes a character in DL to the serial console output - (if enabled.) If no serial port is configured, this routine - does nothing. - - -INT 21h AH=08h [2.09] Get Key without Echo - - Reads a key fron the console input, without echoing it to the - console output. The read character is returned in AL. - - -INT 21h AH=09h [2.01] Write DOS String to Console - - Writes a DOS $-terminated string in DS:DX to the console. - - -INT 21h AH=0Bh [2.00] Check Keyboard - - Returns AL=FFh if there is a keystroke waiting (which can then - be read with INT 21h, AH=01h or AH=08h), otherwise AL=00h. - - -INT 21h AH=30h [2.00] Check DOS Version - - This function returns AX=BX=CX=DX=0, corresponding to a - hypothetical "DOS 0.0", but the high parts of EAX-EBX-ECX-EDX - spell "SYSLINUX": - - EAX=59530000h EBX=4C530000h ECX=4E490000h EDX=58550000h - - This function can thus be used to distinguish running on - Syslinux from running on DOS. - - - ++++ SYSLINUX-SPECIFIC API CALLS ++++ - -Syslinux-specific API calls are executed using INT 22h, with a -function number in AX. INT 22h is used by DOS for internal purposes; -do not execute INT 22h under DOS. - -DOS-compatible function INT 21h, AH=30h can be used to detect if the -Syslinux API calls are available. - -Any register not specifically listed as modified is preserved; -however, future versions of Syslinux may add additional output -registers to existing calls. - -All calls return CF=0 on success, CF=1 on failure. The noted outputs -apply if CF=0 only unless otherwise noted. All calls clobber the -arithmetric flags (CF, PF, AF, ZF, SF and OF) but leave all other -flags unchanged unless otherwise noted. - - -AX=0001h [2.00] Get Version - - Input: AX 0001h - Output: AX number of INT 22h API functions available - CH Syslinux major version number - CL Syslinux minor version number - DL Syslinux derivative ID (e.g. 32h = PXELINUX) - ES:SI Syslinux version string - ES:DI Syslinux copyright string - - This API call returns the Syslinux version and API - information. - - Note: before version 3.86, the version string had a leading CR LF - and the copyright string had a leading space. The strings might - still contain trailing CR and/or LF. - - -AX=0002h [2.01] Write String - - Input: AX 0002h - ES:BX null-terminated string - Output: None - - Writes a null-terminated string on the console. - - -AX=0003h [2.01] Run command - - Input: AX 0003h - ES:BX null-terminated command string - Output: Does not return - - This API call terminates the program and executes the command - string as if the user had entered it at the Syslinux command - line. This API call does not return. - - -AX=0004h [2.01] Run default command - - Input: AX 0004h - Output: Does not return - - This API call terminates the program and executes the default - command string as if the user had pressed Enter alone on the - Syslinux command line. This API call does not return. - - -AX=0005h [2.00] Force text mode - - Input: AX 0005h - Output: None - - If the screen was in graphics mode (due to displaying a splash - screen using the <Ctrl-X> command in a message file, or - similar), return to text mode. - - -AX=0006h [2.08] Open file - - Input: AX 0006h - ES:SI null-terminated filename - Output: SI file handle - EAX length of file in bytes, or -1 - CX file block size - - Open a file for reading. The exact syntax of the filenames - allowed depends on the particular Syslinux derivative. - - The Syslinux file system is block-oriented. The size of a - block will always be a power of two and no greater than 16K. - - Note: Syslinux considers a zero-length file to be nonexistent. - - In 3.70 or later, EAX can contain -1 indicating that the file - length is unknown. - - 32-BIT VERSION: - - int cs_pm->open_file(const char *filename, struct com32_filedata *data) - - filename - null-terminated filename - data - pointer to a file data buffer - - Returns the file handle, or -1 on failure. - The file data buffer contains block size and file size. - - -AX=0007h [2.08] Read file - - Input: AX 0007h - SI file handle - ES:BX buffer - CX number of blocks to read - Output: SI file handle, or 0 if EOF was reached - ECX number of bytes read [3.70] - - Read blocks from a file. Note that the file handle that is - returned in SI may not be the same value that was passed in. - - If end of file was reached (SI=0), the file was automatically - closed. - - In 3.70 or later, ECX returns the number of bytes read. This - will always be a multiple of the block size unless EOF is - reached. - - The address of the buffer (ES:BX) should be at least 512-byte - aligned. Syslinux guarantees at least this alignment for the - COMBOOT load segment or the COM32 bounce buffer. - - Keep in mind that a "file" may be a TFTP connection, and that - leaving a file open for an extended period of time may result - in a timeout. - - WARNING: Calling this function with an invalid file handle - will probably crash the system. - - 32-BIT VERSION: - - size_t cs_pm->read_file(uint16_t *handle, void *buf, size_t blocks) - - handle - file handle (input and output, set to zero on end of file) - buf - buffer to write to - blocks - number of blocks to read - - Returns number of bytes read, or 0 on failure. - - -AX=0008h [2.08] Close file - - Input: AX 0008h - SI file handle - 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. - - 32-BIT VERSION: - - void cs_pm->close_file(uint16_t handle) - - handle - file handle to close - - -AX=0009h [2.00] Call PXE Stack [PXELINUX ONLY] - - Input: AX 0009h - BX PXE function number - ES:DI PXE parameter structure 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 - CL 9 (to get a valid return in CL for all versions) - Output: AL 31h (SYSLINUX), 34h (EXTLINUX) - DL drive number - CL sector size as a power of 2 (9 = 512 bytes) [3.35] - CH mode [3.73] - 1 = CBIOS mode - 2 = EBIOS mode - ES:BX pointer to partition table entry (if DL >= 80h) - FS:SI pointer to initial ES:DI value [3.53] - GS:DI pointer to partition offset (QWORD) [4.00] - - Note: This function was broken in EXTLINUX 3.00-3.02. - - On boot, ES:DI is supposed to point to the BIOS $PnP - structure, although in practice most operating systems - will search for it in memory. However, preserving - this while chainloading is probably a good idea. - - Note that FS:SI is a pointer to a memory location - containing the original ES:DI value, not the value - itself. - - - [PXELINUX] - Input: AX 000Ah - Output: AL 32h (PXELINUX) - DX PXE API version detected (DH=major, DL=minor) - ECX Local IP number (network byte order) [3.85] - ES:BX pointer to PXENV+ or !PXE structure - FS:SI pointer to original stack with invocation record - GS:DI pointer to network information [4.00] - - 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 - - GS:DI points to a structure of the following form: - - [gs:di+0] 4 - IPv4 - [gs:di+4] My IP - [gs:di+8] Boot server IP - [gs:di+12] Gateway IP - [gs:di+16] Netmask - - [ISOLINUX] - Input: AX 000Ah - Output: AL 33h (ISOLINUX) - DL drive number - CL 11 (sector size as a power of 2) [3.35] - CH mode [3.73] - 0 = El Torito - 1 = Hybrid (hard disk), CBIOS mode - 2 = Hybrid (hard disk), EBIOS mode - ES:BX pointer to El Torito spec packet - FS:SI pointer to initial ES:DI value [3.53] - GS:DI pointer to partition offset (QWORD) [4.00] - - 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. - - -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.txt) - -> 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: None - - 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: AX 0010h - 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] Obsoleted in 3.80 - - -AX=0012h [3.50] Cleanup, shuffle and boot - Input: AX 0012h - DX derivative-specific flags (see function 000Ch) - 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(). - - Starting in version 3.50, if the source address is -1 - (FFFFFFFFh) then the block specified by the destination - address and the length is set to all zero. - - Starting in version 3.50, if the destination address is -1 - (FFFFFFFFh) then the data block is loaded as a new set of - descriptors, and processing is continued (and unprocessed - descriptors are lost, this is thus typically only used as the - last descriptor in a block.) The block must still fit in the - internal descriptor buffer (see function 0011h), but can, of - course, itself chain another block. - - - 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. - - This interface was probably broken before version 3.50. - - -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.txt 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 Type of file (since 3.50) - 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.) - - The file types are defined as follows: - - Equivalent - EDX Config Extensions Type of file - 0 KERNEL Determined by filename extension - 1 LINUX none Linux kernel image - 2 BOOT .bs .bin Bootstrap program - 3 BSS .bss Boot sector with patch [SYSLINUX] - 4 PXE .0 PXE Network Bootstrap Prog [PXELINUX] - 5 FDIMAGE .img Floppy disk image [ISOLINUX] - 6 COMBOOT .com .cbt 16-bit COMBOOT program - 7 COM32 .c32 COM32 program - 8 CONFIG Configuration file - - -AX=0017h [3.30] Report video mode change - Input: AX 0017h - BX Video mode flags - Bit 0: graphics mode - Bit 1: non-default mode - Bit 2: VESA mode - Bit 3: text functions not supported - CX For graphics modes, pixel columns - DX For graphics modes, pixel rows - Output: None - - This function is used to report video mode changes to - Syslinux. It does NOT actually change the video mode, but - rather, allows Syslinux to take appropriate action in response - to a video mode change. Modes that cannot be exited either - with the conventional BIOS mode set command (INT 10h, AH=00h) - or the VESA VBE mode set command (INT 10h, AX=4F02h) should - not be used. - - This function returns with a failure if BX contains any bits - which are undefined in the current version of Syslinux. - - The following bits in BX are currently defined: - - Bit 0: graphics mode - - Indicates that the mode is a graphics mode, as opposed - to a text mode. - - Bit 1: non-standard mode - - A non-standard mode is any mode except text mode and - graphics mode 0012h (VGA 640x480, 16 color.) - - Bit 2: VESA mode - - This mode is a VESA mode, and has to be exited with - the VESA VBE API (INT 10h, AX=4F02h) as opposed to the - conventional BIOS API (INT 10h, AH=00h). - - Bit 3: Text functions not supported - - This indicates that the BIOS text output functions - (INT 10h, AH=02h, 03h, 06h, 09h, 0Eh, 11h) don't work. - If this bit is set, Syslinux will reset the mode - before printing any characters on the screen. - - This is common for VESA modes. - - -AX=0018h [3.30] Query custom font - Input: AX 0018h - Output: AL Height of custom font in scan lines, or zero - ES:BX Pointer to custom font in memory - - This call queries if a custom display font has been loaded via - the "font" configuration file command. If no custom font has - been loaded, AL contains zero. - - -AX=0019h [3.50] Read disk [SYSLINUX, ISOLINUX, EXTLINUX] - Input: AX 0019h - EDX Sector number (LSW) - ESI Sector number (MSW) [4.00] - EDI Reserved - MUST BE ZERO - CX Sector count - ES:BX Buffer address - Output: None - - Read disk blocks from the active filesystem (partition); for - disks, sector number zero is the boot sector. For ISOLINUX, - this call reads the CD-ROM. - - For compatiblity with all systems, the buffer should - *neither* cross 64K boundaries, *nor* wrap around the segment. - - This routine reports "boot failed" (and does not return) on - disk error. - - Note: for ISOLINUX in hybrid mode, this call uses simulated - 2048-byte CD-ROM sector numbers. - - -AX=001Ah [3.50] Obsoleted in 3.80 - - -AX=001Bh [3.50] Obsoleted in 3.80 - - -AX=001Ch [3.60] Get pointer to auxilliary data vector - Input: AX 001Ch - Output: ES:BX Auxilliary data vector - CX Size of the ADV (currently 500 bytes) - - The auxillary data vector is a tagged data structure used - to carry a small amount of information (up to 500 bytes) from - one boot to another. - - -AX=001Dh [3.60] Write auxilliary data vector - Input: AX 001Dh - Output: None - - Write the auxilliary data vector back to disk. Returns - failure for non-disk-based derivatives unless the "auxdata" - configuration command is used to specify a disk location - (not yet implemented.) - - In a future version, PXELINUX may end up attempting to save - the ADV on the server via TFTP write. - - -AX=001Eh [3.74] Keyboard remapping table - Input: AX 001Eh - DX 0000h - all other values reserved - Output: AX format version (1) - CX length in bytes (256) - ES:BX pointer to keyboard table - - This call queries the keyboard remapping table. For the current - version, the format code is always 1 and the length is always - 256. This version can be updated simply by overwriting the version - in memory; this may not be true in the future. - - -AX=001Fh [3.74] Get current working directory - Input: AX 0001Fh - Output: ES:BX null-terminated directory name string - - Returns the current working directory. - - -AX=0020h [3.74] Obsoleted in 4.00 -AX=0021h [3.74] Obsoleted in 4.00 -AX=0022h [3.74] Obsoleted in 4.00 - - These three functions provided opendir/readdir/closedir - functionality in the late 3.xx series. They have been - replaced by the protected-mode interface. - - -AX=0023h [3.80] Get shuffler parameters - Input: AX 0023h - Output: CX size of shuffler "safe area" in bytes - Other registers reserved for future use - - This call gives the size of the required shuffler "safe area", - in bytes; for call 0024h. In the future, it may provide - additional parameters. - - -AX=0024h [3.80] Cleanup, shuffle and boot, raw version - Input: AX 0024h - DX derivative-specific flags (see function 000Ch) - EDI shuffle descriptor list safe area - ESI shuffle descriptor list source - ECX byte count of shuffle descriptor list - Output: Does not return - - 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. - - Unlike previous obsolete versions of this function, there are - no restrictions that copies must not touch memory below - address 7C00h. Either the shuffle descriptor list or the safe - area (or both) may be located in high memory. - - ESI points to a list of descriptors each of the form: - - Offset Size Meaning - 0 dword destination address - 4 dword source address (-1 = zero) - 8 dword length in bytes (0 = end of list) - - The copies are overlap-safe, like memmove(). - - Before actually executing the move list, the list is moved to - the address specified in EDI. The caller is responsibe to - ensure that the moved descriptor list plus a "safe area" - immediately afterwards (the size of which is specified by - function 0023h) is not disturbed by the copy sequence. It is, - however, safe to overwrite descriptors already consumed. - - If the source address is -1 (FFFFFFFFh) then the block - specified by the destination address and the length is set to - all zero. - - The list is terminated by an entry with length 0. For that - entry, the destination is used as an entry point, and the - source represents the type of entry point: - - 0 16-bit protected mode (dst is CS.base) - 1 Flat 32-bit protected mode (dst is EIP) - - This routine does not set up any GPR register state - whatsoever, including stack. It is the responsibility of the - caller to make sure the entry point provided sets up any - registers needed. - - For mode 0 (16-bit real mode), EAX will contain CR0 with bit 0 - masked out, suitable for loading into CR0 to immediately enter - real mode. Note: if real-mode entry is planned, - (CS.base & 0xfff0000f) should == 0 for compatibility with KVM, - and possibly other virtualization solutions. - - In both mode 0 and mode 1, the data segments will be loaded - with read/write data segments, matching the respective code - segment. For mode 0, B=0 and the limits will be 64K, for mode - 1, B=1 and the limits will be 4 GB. - - - ++++ 32-BIT ONLY API CALLS ++++ - -void *pm_cs->lmalloc(size_t bytes) - - Allocate a buffer in low memory (below 1 MB). - - -void pm_cs->lfree(void *ptr) - - Free a buffer allocated with pm_cs->lmalloc(). - - -DIR *pm_cs->opendir(const char *pathname) - - Open a directory. - - -struct dirent *pm_cs->readdir(DIR *dir) - - Read an entry from a directory. The entry is returned in a - static buffer. - - -int pm_cs->closedir(DIR *dir) - - Close a directory. |