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u-boot-1.1.6 源码包

		ratio. Valid values are 1 (default if undefined) and
		2. The core frequency as calculated above is multiplied
		by this value.

- Linux Kernel Interface:
		CONFIG_CLOCKS_IN_MHZ

		U-Boot stores all clock information in Hz
		internally. For binary compatibility with older Linux
		kernels (which expect the clocks passed in the
		bd_info data to be in MHz) the environment variable
		"clocks_in_mhz" can be defined so that U-Boot
		converts clock data to MHZ before passing it to the
		Linux kernel.
		When CONFIG_CLOCKS_IN_MHZ is defined, a definition of
		"clocks_in_mhz=1" is  automatically  included  in  the
		default environment.

		CONFIG_MEMSIZE_IN_BYTES		[relevant for MIPS only]

		When transfering memsize parameter to linux, some versions
		expect it to be in bytes, others in MB.
		Define CONFIG_MEMSIZE_IN_BYTES to make it in bytes.

		CONFIG_OF_FLAT_TREE

		New kernel versions are expecting firmware settings to be
		passed using flat open firmware trees.
		The environment variable "disable_of", when set, disables this
		functionality.

		CONFIG_OF_FLAT_TREE_MAX_SIZE

		The maximum size of the constructed OF tree.

		OF_CPU - The proper name of the cpus node.
		OF_SOC - The proper name of the soc node.
		OF_TBCLK - The timebase frequency.
		OF_STDOUT_PATH - The path to the console device

		CONFIG_OF_HAS_BD_T

		The resulting flat device tree will have a copy of the bd_t.
		Space should be pre-allocated in the dts for the bd_t.

		CONFIG_OF_HAS_UBOOT_ENV

		The resulting flat device tree will have a copy of u-boot's
		environment variables

		CONFIG_OF_BOARD_SETUP

		Board code has addition modification that it wants to make
		to the flat device tree before handing it off to the kernel

		CONFIG_OF_BOOT_CPU

		This define fills in the correct boot cpu in the boot
		param header, the default value is zero if undefined.

- Serial Ports:
		CFG_PL010_SERIAL

		Define this if you want support for Amba PrimeCell PL010 UARTs.

		CFG_PL011_SERIAL

		Define this if you want support for Amba PrimeCell PL011 UARTs.

		CONFIG_PL011_CLOCK

		If you have Amba PrimeCell PL011 UARTs, set this variable to
		the clock speed of the UARTs.

		CONFIG_PL01x_PORTS

		If you have Amba PrimeCell PL010 or PL011 UARTs on your board,
		define this to a list of base addresses for each (supported)
		port. See e.g. include/configs/versatile.h


- Console Interface:
		Depending on board, define exactly one serial port
		(like CONFIG_8xx_CONS_SMC1, CONFIG_8xx_CONS_SMC2,
		CONFIG_8xx_CONS_SCC1, ...), or switch off the serial
		console by defining CONFIG_8xx_CONS_NONE

		Note: if CONFIG_8xx_CONS_NONE is defined, the serial
		port routines must be defined elsewhere
		(i.e. serial_init(), serial_getc(), ...)

		CONFIG_CFB_CONSOLE
		Enables console device for a color framebuffer. Needs following
		defines (cf. smiLynxEM, i8042, board/eltec/bab7xx)
			VIDEO_FB_LITTLE_ENDIAN	graphic memory organisation
						(default big endian)
			VIDEO_HW_RECTFILL	graphic chip supports
						rectangle fill
						(cf. smiLynxEM)
			VIDEO_HW_BITBLT		graphic chip supports
						bit-blit (cf. smiLynxEM)
			VIDEO_VISIBLE_COLS	visible pixel columns
						(cols=pitch)
			VIDEO_VISIBLE_ROWS	visible pixel rows
			VIDEO_PIXEL_SIZE	bytes per pixel
			VIDEO_DATA_FORMAT	graphic data format
						(0-5, cf. cfb_console.c)
			VIDEO_FB_ADRS		framebuffer address
			VIDEO_KBD_INIT_FCT	keyboard int fct
						(i.e. i8042_kbd_init())
			VIDEO_TSTC_FCT		test char fct
						(i.e. i8042_tstc)
			VIDEO_GETC_FCT		get char fct
						(i.e. i8042_getc)
			CONFIG_CONSOLE_CURSOR	cursor drawing on/off
						(requires blink timer
						cf. i8042.c)
			CFG_CONSOLE_BLINK_COUNT blink interval (cf. i8042.c)
			CONFIG_CONSOLE_TIME	display time/date info in
						upper right corner
						(requires CFG_CMD_DATE)
			CONFIG_VIDEO_LOGO	display Linux logo in
						upper left corner
			CONFIG_VIDEO_BMP_LOGO	use bmp_logo.h instead of
						linux_logo.h for logo.
						Requires CONFIG_VIDEO_LOGO
			CONFIG_CONSOLE_EXTRA_INFO
						addional board info beside
						the logo

		When CONFIG_CFB_CONSOLE is defined, video console is
		default i/o. Serial console can be forced with
		environment 'console=serial'.

		When CONFIG_SILENT_CONSOLE is defined, all console
		messages (by U-Boot and Linux!) can be silenced with
		the "silent" environment variable. See
		doc/README.silent for more information.

- Console Baudrate:
		CONFIG_BAUDRATE - in bps
		Select one of the baudrates listed in
		CFG_BAUDRATE_TABLE, see below.
		CFG_BRGCLK_PRESCALE, baudrate prescale

- Interrupt driven serial port input:
		CONFIG_SERIAL_SOFTWARE_FIFO

		PPC405GP only.
		Use an interrupt handler for receiving data on the
		serial port. It also enables using hardware handshake
		(RTS/CTS) and UART's built-in FIFO. Set the number of
		bytes the interrupt driven input buffer should have.

		Leave undefined to disable this feature, including
		disable the buffer and hardware handshake.

- Console UART Number:
		CONFIG_UART1_CONSOLE

		AMCC PPC4xx only.
		If defined internal UART1 (and not UART0) is used
		as default U-Boot console.

- Boot Delay:	CONFIG_BOOTDELAY - in seconds
		Delay before automatically booting the default image;
		set to -1 to disable autoboot.

		See doc/README.autoboot for these options that
		work with CONFIG_BOOTDELAY. None are required.
		CONFIG_BOOT_RETRY_TIME
		CONFIG_BOOT_RETRY_MIN
		CONFIG_AUTOBOOT_KEYED
		CONFIG_AUTOBOOT_PROMPT
		CONFIG_AUTOBOOT_DELAY_STR
		CONFIG_AUTOBOOT_STOP_STR
		CONFIG_AUTOBOOT_DELAY_STR2
		CONFIG_AUTOBOOT_STOP_STR2
		CONFIG_ZERO_BOOTDELAY_CHECK
		CONFIG_RESET_TO_RETRY

- Autoboot Command:
		CONFIG_BOOTCOMMAND
		Only needed when CONFIG_BOOTDELAY is enabled;
		define a command string that is automatically executed
		when no character is read on the console interface
		within "Boot Delay" after reset.

		CONFIG_BOOTARGS
		This can be used to pass arguments to the bootm
		command. The value of CONFIG_BOOTARGS goes into the
		environment value "bootargs".

		CONFIG_RAMBOOT and CONFIG_NFSBOOT
		The value of these goes into the environment as
		"ramboot" and "nfsboot" respectively, and can be used
		as a convenience, when switching between booting from
		ram and nfs.

- Pre-Boot Commands:
		CONFIG_PREBOOT

		When this option is #defined, the existence of the
		environment variable "preboot" will be checked
		immediately before starting the CONFIG_BOOTDELAY
		countdown and/or running the auto-boot command resp.
		entering interactive mode.

		This feature is especially useful when "preboot" is
		automatically generated or modified. For an example
		see the LWMON board specific code: here "preboot" is
		modified when the user holds down a certain
		combination of keys on the (special) keyboard when
		booting the systems

- Serial Download Echo Mode:
		CONFIG_LOADS_ECHO
		If defined to 1, all characters received during a
		serial download (using the "loads" command) are
		echoed back. This might be needed by some terminal
		emulations (like "cu"), but may as well just take
		time on others. This setting #define's the initial
		value of the "loads_echo" environment variable.

- Kgdb Serial Baudrate: (if CFG_CMD_KGDB is defined)
		CONFIG_KGDB_BAUDRATE
		Select one of the baudrates listed in
		CFG_BAUDRATE_TABLE, see below.

- Monitor Functions:
		CONFIG_COMMANDS
		Most monitor functions can be selected (or
		de-selected) by adjusting the definition of
		CONFIG_COMMANDS; to select individual functions,
		#define CONFIG_COMMANDS by "OR"ing any of the
		following values:

		#define enables commands:
		-------------------------
		CFG_CMD_ASKENV	* ask for env variable
		CFG_CMD_AUTOSCRIPT Autoscript Support
		CFG_CMD_BDI	  bdinfo
		CFG_CMD_BEDBUG	* Include BedBug Debugger
		CFG_CMD_BMP	* BMP support
		CFG_CMD_BSP	* Board specific commands
		CFG_CMD_BOOTD	  bootd
		CFG_CMD_CACHE	* icache, dcache
		CFG_CMD_CONSOLE	  coninfo
		CFG_CMD_DATE	* support for RTC, date/time...
		CFG_CMD_DHCP	* DHCP support
		CFG_CMD_DIAG	* Diagnostics
		CFG_CMD_DOC	* Disk-On-Chip Support
		CFG_CMD_DTT	* Digital Therm and Thermostat
		CFG_CMD_ECHO	  echo arguments
		CFG_CMD_EEPROM	* EEPROM read/write support
		CFG_CMD_ELF	* bootelf, bootvx
		CFG_CMD_ENV	  saveenv
		CFG_CMD_FDC	* Floppy Disk Support
		CFG_CMD_FAT	* FAT partition support
		CFG_CMD_FDOS	* Dos diskette Support
		CFG_CMD_FLASH	  flinfo, erase, protect
		CFG_CMD_FPGA	  FPGA device initialization support
		CFG_CMD_HWFLOW	* RTS/CTS hw flow control
		CFG_CMD_I2C	* I2C serial bus support
		CFG_CMD_IDE	* IDE harddisk support
		CFG_CMD_IMI	  iminfo
		CFG_CMD_IMLS	  List all found images
		CFG_CMD_IMMAP	* IMMR dump support
		CFG_CMD_IRQ	* irqinfo
		CFG_CMD_ITEST	  Integer/string test of 2 values
		CFG_CMD_JFFS2	* JFFS2 Support
		CFG_CMD_KGDB	* kgdb
		CFG_CMD_LOADB	  loadb
		CFG_CMD_LOADS	  loads
		CFG_CMD_MEMORY	  md, mm, nm, mw, cp, cmp, crc, base,
				  loop, loopw, mtest
		CFG_CMD_MISC	  Misc functions like sleep etc
		CFG_CMD_MMC	* MMC memory mapped support
		CFG_CMD_MII	* MII utility commands
		CFG_CMD_NAND	* NAND support
		CFG_CMD_NET	  bootp, tftpboot, rarpboot
		CFG_CMD_PCI	* pciinfo
		CFG_CMD_PCMCIA	* PCMCIA support
		CFG_CMD_PING	* send ICMP ECHO_REQUEST to network host
		CFG_CMD_PORTIO	* Port I/O
		CFG_CMD_REGINFO * Register dump
		CFG_CMD_RUN	  run command in env variable
		CFG_CMD_SAVES	* save S record dump
		CFG_CMD_SCSI	* SCSI Support
		CFG_CMD_SDRAM	* print SDRAM configuration information
				  (requires CFG_CMD_I2C)
		CFG_CMD_SETGETDCR Support for DCR Register access (4xx only)
		CFG_CMD_SPI	* SPI serial bus support
		CFG_CMD_USB	* USB support
		CFG_CMD_VFD	* VFD support (TRAB)
		CFG_CMD_BSP	* Board SPecific functions
		CFG_CMD_CDP	* Cisco Discover Protocol support
		-----------------------------------------------
		CFG_CMD_ALL	all

		CONFIG_CMD_DFL	Default configuration; at the moment
				this is includes all commands, except
				the ones marked with "*" in the list
				above.

		If you don't define CONFIG_COMMANDS it defaults to
		CONFIG_CMD_DFL in include/cmd_confdefs.h. A board can
		override the default settings in the respective
		include file.

		EXAMPLE: If you want all functions except of network
		support you can write:

		#define CONFIG_COMMANDS (CFG_CMD_ALL & ~CFG_CMD_NET)


	Note:	Don't enable the "icache" and "dcache" commands
		(configuration option CFG_CMD_CACHE) unless you know
		what you (and your U-Boot users) are doing. Data
		cache cannot be enabled on systems like the 8xx or
		8260 (where accesses to the IMMR region must be
		uncached), and it cannot be disabled on all other
		systems where we (mis-) use the data cache to hold an
		initial stack and some data.


		XXX - this list needs to get updated!

- Watchdog:
		CONFIG_WATCHDOG
		If this variable is defined, it enables watchdog
		support. There must be support in the platform specific
		code for a watchdog. For the 8xx and 8260 CPUs, the
		SIU Watchdog feature is enabled in the SYPCR
		register.

- U-Boot Version:
		CONFIG_VERSION_VARIABLE
		If this variable is defined, an environment variable
		named "ver" is created by U-Boot showing the U-Boot
		version as printed by the "version" command.
		This variable is readonly.

- Real-Time Clock:

		When CFG_CMD_DATE is selected, the type of the RTC
		has to be selected, too. Define exactly one of the
		following options:

		CONFIG_RTC_MPC8xx	- use internal RTC of MPC8xx
		CONFIG_RTC_PCF8563	- use Philips PCF8563 RTC
		CONFIG_RTC_MC146818	- use MC146818 RTC
		CONFIG_RTC_DS1307	- use Maxim, Inc. DS1307 RTC
		CONFIG_RTC_DS1337	- use Maxim, Inc. DS1337 RTC
		CONFIG_RTC_DS1338	- use Maxim, Inc. DS1338 RTC
		CONFIG_RTC_DS164x	- use Dallas DS164x RTC
		CONFIG_RTC_MAX6900	- use Maxim, Inc. MAX6900 RTC

		Note that if the RTC uses I2C, then the I2C interface
		must also be configured. See I2C Support, below.

- Timestamp Support:

		When CONFIG_TIMESTAMP is selected, the timestamp
		(date and time) of an image is printed by image
		commands like bootm or iminfo. This option is
		automatically enabled when you select CFG_CMD_DATE .

- Partition Support:
		CONFIG_MAC_PARTITION and/or CONFIG_DOS_PARTITION
		and/or CONFIG_ISO_PARTITION

		If IDE or SCSI support	is  enabled  (CFG_CMD_IDE  or
		CFG_CMD_SCSI) you must configure support for at least
		one partition type as well.

- IDE Reset method:
		CONFIG_IDE_RESET_ROUTINE - this is defined in several
		board configurations files but used nowhere!

		CONFIG_IDE_RESET - is this is defined, IDE Reset will
		be performed by calling the function
			ide_set_reset(int reset)
		which has to be defined in a board specific file

- ATAPI Support:
		CONFIG_ATAPI

		Set this to enable ATAPI support.

- LBA48 Support
		CONFIG_LBA48

		Set this to enable support for disks larger than 137GB
		Also look at CFG_64BIT_LBA ,CFG_64BIT_VSPRINTF and CFG_64BIT_STRTOUL
		Whithout these , LBA48 support uses 32bit variables and will 'only'
		support disks up to 2.1TB.

		CFG_64BIT_LBA:
			When enabled, makes the IDE subsystem use 64bit sector addresses.
			Default is 32bit.

- SCSI Support:
		At the moment only there is only support for the
		SYM53C8XX SCSI controller; define
		CONFIG_SCSI_SYM53C8XX to enable it.

		CFG_SCSI_MAX_LUN [8], CFG_SCSI_MAX_SCSI_ID [7] and