README

 -125	common/image.c		Ramdisk subimage hash verification failed
  126	common/image.c		Ramdisk subimage hash verification OK
 -126	common/image.c		Ramdisk subimage for unsupported architecture
  127	common/image.c		Architecture check OK
 -127	common/image.c		Can't get ramdisk subimage data/size
  128	common/image.c		Got ramdisk subimage data/size
  129	common/image.c		Can't get ramdisk load address
 -129	common/image.c		Got ramdisk load address

 -130	common/cmd_doc.c	Incorrect FIT image format
  131	common/cmd_doc.c	FIT image format OK

 -140	common/cmd_ide.c	Incorrect FIT image format
  141	common/cmd_ide.c	FIT image format OK

 -150	common/cmd_nand.c	Incorrect FIT image format
  151	common/cmd_nand.c	FIT image format OK

- legacy image format:
		CONFIG_IMAGE_FORMAT_LEGACY
		enables the legacy image format support in U-Boot.

		Default:
		enabled if CONFIG_FIT_SIGNATURE is not defined.

		CONFIG_DISABLE_IMAGE_LEGACY
		disable the legacy image format

		This define is introduced, as the legacy image format is
		enabled per default for backward compatibility.

- FIT image support:
		CONFIG_FIT_DISABLE_SHA256
		Supporting SHA256 hashes has quite an impact on binary size.
		For constrained systems sha256 hash support can be disabled
		with this option.

		TODO(sjg@chromium.org): Adjust this option to be positive,
		and move it to Kconfig

- Standalone program support:
		CONFIG_STANDALONE_LOAD_ADDR

		This option defines a board specific value for the
		address where standalone program gets loaded, thus
		overwriting the architecture dependent default
		settings.

- Frame Buffer Address:
		CONFIG_FB_ADDR

		Define CONFIG_FB_ADDR if you want to use specific
		address for frame buffer.  This is typically the case
		when using a graphics controller has separate video
		memory.  U-Boot will then place the frame buffer at
		the given address instead of dynamically reserving it
		in system RAM by calling lcd_setmem(), which grabs
		the memory for the frame buffer depending on the
		configured panel size.

		Please see board_init_f function.

- Automatic software updates via TFTP server
		CONFIG_UPDATE_TFTP
		CONFIG_UPDATE_TFTP_CNT_MAX
		CONFIG_UPDATE_TFTP_MSEC_MAX

		These options enable and control the auto-update feature;
		for a more detailed description refer to doc/README.update.

- MTD Support (mtdparts command, UBI support)
		CONFIG_MTD_DEVICE

		Adds the MTD device infrastructure from the Linux kernel.
		Needed for mtdparts command support.

		CONFIG_MTD_PARTITIONS

		Adds the MTD partitioning infrastructure from the Linux
		kernel. Needed for UBI support.

- UBI support
		CONFIG_CMD_UBI

		Adds commands for interacting with MTD partitions formatted
		with the UBI flash translation layer

		Requires also defining CONFIG_RBTREE

		CONFIG_UBI_SILENCE_MSG

		Make the verbose messages from UBI stop printing.  This leaves
		warnings and errors enabled.


		CONFIG_MTD_UBI_WL_THRESHOLD
		This parameter defines the maximum difference between the highest
		erase counter value and the lowest erase counter value of eraseblocks
		of UBI devices. When this threshold is exceeded, UBI starts performing
		wear leveling by means of moving data from eraseblock with low erase
		counter to eraseblocks with high erase counter.

		The default value should be OK for SLC NAND flashes, NOR flashes and
		other flashes which have eraseblock life-cycle 100000 or more.
		However, in case of MLC NAND flashes which typically have eraseblock
		life-cycle less than 10000, the threshold should be lessened (e.g.,
		to 128 or 256, although it does not have to be power of 2).

		default: 4096

		CONFIG_MTD_UBI_BEB_LIMIT
		This option specifies the maximum bad physical eraseblocks UBI
		expects on the MTD device (per 1024 eraseblocks). If the
		underlying flash does not admit of bad eraseblocks (e.g. NOR
		flash), this value is ignored.

		NAND datasheets often specify the minimum and maximum NVM
		(Number of Valid Blocks) for the flashes' endurance lifetime.
		The maximum expected bad eraseblocks per 1024 eraseblocks
		then can be calculated as "1024 * (1 - MinNVB / MaxNVB)",
		which gives 20 for most NANDs (MaxNVB is basically the total
		count of eraseblocks on the chip).

		To put it differently, if this value is 20, UBI will try to
		reserve about 1.9% of physical eraseblocks for bad blocks
		handling. And that will be 1.9% of eraseblocks on the entire
		NAND chip, not just the MTD partition UBI attaches. This means
		that if you have, say, a NAND flash chip admits maximum 40 bad
		eraseblocks, and it is split on two MTD partitions of the same
		size, UBI will reserve 40 eraseblocks when attaching a
		partition.

		default: 20

		CONFIG_MTD_UBI_FASTMAP
		Fastmap is a mechanism which allows attaching an UBI device
		in nearly constant time. Instead of scanning the whole MTD device it
		only has to locate a checkpoint (called fastmap) on the device.
		The on-flash fastmap contains all information needed to attach
		the device. Using fastmap makes only sense on large devices where
		attaching by scanning takes long. UBI will not automatically install
		a fastmap on old images, but you can set the UBI parameter
		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT to 1 if you want so. Please note
		that fastmap-enabled images are still usable with UBI implementations
		without	fastmap support. On typical flash devices the whole fastmap
		fits into one PEB. UBI will reserve PEBs to hold two fastmaps.

		CONFIG_MTD_UBI_FASTMAP_AUTOCONVERT
		Set this parameter to enable fastmap automatically on images
		without a fastmap.
		default: 0

		CONFIG_MTD_UBI_FM_DEBUG
		Enable UBI fastmap debug
		default: 0

- UBIFS support
		CONFIG_CMD_UBIFS

		Adds commands for interacting with UBI volumes formatted as
		UBIFS.  UBIFS is read-only in u-boot.

		Requires UBI support as well as CONFIG_LZO

		CONFIG_UBIFS_SILENCE_MSG

		Make the verbose messages from UBIFS stop printing.  This leaves
		warnings and errors enabled.

- SPL framework
		CONFIG_SPL
		Enable building of SPL globally.

		CONFIG_SPL_LDSCRIPT
		LDSCRIPT for linking the SPL binary.

		CONFIG_SPL_MAX_FOOTPRINT
		Maximum size in memory allocated to the SPL, BSS included.
		When defined, the linker checks that the actual memory
		used by SPL from _start to __bss_end does not exceed it.
		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
		must not be both defined at the same time.

		CONFIG_SPL_MAX_SIZE
		Maximum size of the SPL image (text, data, rodata, and
		linker lists sections), BSS excluded.
		When defined, the linker checks that the actual size does
		not exceed it.

		CONFIG_SPL_TEXT_BASE
		TEXT_BASE for linking the SPL binary.

		CONFIG_SPL_RELOC_TEXT_BASE
		Address to relocate to.  If unspecified, this is equal to
		CONFIG_SPL_TEXT_BASE (i.e. no relocation is done).

		CONFIG_SPL_BSS_START_ADDR
		Link address for the BSS within the SPL binary.

		CONFIG_SPL_BSS_MAX_SIZE
		Maximum size in memory allocated to the SPL BSS.
		When defined, the linker checks that the actual memory used
		by SPL from __bss_start to __bss_end does not exceed it.
		CONFIG_SPL_MAX_FOOTPRINT and CONFIG_SPL_BSS_MAX_SIZE
		must not be both defined at the same time.

		CONFIG_SPL_STACK
		Adress of the start of the stack SPL will use

		CONFIG_SPL_PANIC_ON_RAW_IMAGE
		When defined, SPL will panic() if the image it has
		loaded does not have a signature.
		Defining this is useful when code which loads images
		in SPL cannot guarantee that absolutely all read errors
		will be caught.
		An example is the LPC32XX MLC NAND driver, which will
		consider that a completely unreadable NAND block is bad,
		and thus should be skipped silently.

		CONFIG_SPL_RELOC_STACK
		Adress of the start of the stack SPL will use after
		relocation.  If unspecified, this is equal to
		CONFIG_SPL_STACK.

		CONFIG_SYS_SPL_MALLOC_START
		Starting address of the malloc pool used in SPL.
		When this option is set the full malloc is used in SPL and
		it is set up by spl_init() and before that, the simple malloc()
		can be used if CONFIG_SYS_MALLOC_F is defined.

		CONFIG_SYS_SPL_MALLOC_SIZE
		The size of the malloc pool used in SPL.

		CONFIG_SPL_FRAMEWORK
		Enable the SPL framework under common/.  This framework
		supports MMC, NAND and YMODEM loading of U-Boot and NAND
		NAND loading of the Linux Kernel.

		CONFIG_SPL_OS_BOOT
		Enable booting directly to an OS from SPL.
		See also: doc/README.falcon

		CONFIG_SPL_DISPLAY_PRINT
		For ARM, enable an optional function to print more information
		about the running system.

		CONFIG_SPL_INIT_MINIMAL
		Arch init code should be built for a very small image

		CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_PARTITION
		Partition on the MMC to load U-Boot from when the MMC is being
		used in raw mode

		CONFIG_SYS_MMCSD_RAW_MODE_KERNEL_SECTOR
		Sector to load kernel uImage from when MMC is being
		used in raw mode (for Falcon mode)

		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTOR,
		CONFIG_SYS_MMCSD_RAW_MODE_ARGS_SECTORS
		Sector and number of sectors to load kernel argument
		parameters from when MMC is being used in raw mode
		(for falcon mode)

		CONFIG_SYS_MMCSD_FS_BOOT_PARTITION
		Partition on the MMC to load U-Boot from when the MMC is being
		used in fs mode

		CONFIG_SPL_FS_LOAD_PAYLOAD_NAME
		Filename to read to load U-Boot when reading from filesystem

		CONFIG_SPL_FS_LOAD_KERNEL_NAME
		Filename to read to load kernel uImage when reading
		from filesystem (for Falcon mode)

		CONFIG_SPL_FS_LOAD_ARGS_NAME
		Filename to read to load kernel argument parameters
		when reading from filesystem (for Falcon mode)

		CONFIG_SPL_MPC83XX_WAIT_FOR_NAND
		Set this for NAND SPL on PPC mpc83xx targets, so that
		start.S waits for the rest of the SPL to load before
		continuing (the hardware starts execution after just
		loading the first page rather than the full 4K).

		CONFIG_SPL_SKIP_RELOCATE
		Avoid SPL relocation

		CONFIG_SPL_NAND_BASE
		Include nand_base.c in the SPL.  Requires
		CONFIG_SPL_NAND_DRIVERS.

		CONFIG_SPL_NAND_DRIVERS
		SPL uses normal NAND drivers, not minimal drivers.

		CONFIG_SPL_NAND_ECC
		Include standard software ECC in the SPL

		CONFIG_SPL_NAND_SIMPLE
		Support for NAND boot using simple NAND drivers that
		expose the cmd_ctrl() interface.

		CONFIG_SPL_UBI
		Support for a lightweight UBI (fastmap) scanner and
		loader

		CONFIG_SPL_NAND_RAW_ONLY
		Support to boot only raw u-boot.bin images. Use this only
		if you need to save space.

		CONFIG_SPL_COMMON_INIT_DDR
		Set for common ddr init with serial presence detect in
		SPL binary.

		CONFIG_SYS_NAND_5_ADDR_CYCLE, CONFIG_SYS_NAND_PAGE_COUNT,
		CONFIG_SYS_NAND_PAGE_SIZE, CONFIG_SYS_NAND_OOBSIZE,
		CONFIG_SYS_NAND_BLOCK_SIZE, CONFIG_SYS_NAND_BAD_BLOCK_POS,
		CONFIG_SYS_NAND_ECCPOS, CONFIG_SYS_NAND_ECCSIZE,
		CONFIG_SYS_NAND_ECCBYTES
		Defines the size and behavior of the NAND that SPL uses
		to read U-Boot

		CONFIG_SPL_NAND_BOOT
		Add support NAND boot

		CONFIG_SYS_NAND_U_BOOT_OFFS
		Location in NAND to read U-Boot from

		CONFIG_SYS_NAND_U_BOOT_DST
		Location in memory to load U-Boot to

		CONFIG_SYS_NAND_U_BOOT_SIZE
		Size of image to load

		CONFIG_SYS_NAND_U_BOOT_START
		Entry point in loaded image to jump to

		CONFIG_SYS_NAND_HW_ECC_OOBFIRST
		Define this if you need to first read the OOB and then the
		data. This is used, for example, on davinci platforms.

		CONFIG_SPL_OMAP3_ID_NAND
		Support for an OMAP3-specific set of functions to return the
		ID and MFR of the first attached NAND chip, if present.

		CONFIG_SPL_RAM_DEVICE
		Support for running image already present in ram, in SPL binary

		CONFIG_SPL_PAD_TO
		Image offset to which the SPL should be padded before appending
		the SPL payload. By default, this is defined as
		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.

		CONFIG_SPL_TARGET
		Final target image containing SPL and payload.  Some SPLs
		use an arch-specific makefile fragment instead, for
		example if more than one image needs to be produced.

		CONFIG_FIT_SPL_PRINT
		Printing information about a FIT image adds quite a bit of
		code to SPL. So this is normally disabled in SPL. Use this
		option to re-enable it. This will affect the output of the
		bootm command when booting a FIT image.

- TPL framework
		CONFIG_TPL
		Enable building of TPL globally.

		CONFIG_TPL_PAD_TO
		Image offset to which the TPL should be padded before appending
		the TPL payload. By default, this is defined as
		CONFIG_SPL_MAX_SIZE, or 0 if CONFIG_SPL_MAX_SIZE is undefined.
		CONFIG_SPL_PAD_TO must be either 0, meaning to append the SPL
		payload without any padding, or >= CONFIG_SPL_MAX_SIZE.

- Interrupt support (PPC):

		There are common interrupt_init() and timer_interrupt()
		for all PPC archs. interrupt_init() calls interrupt_init_cpu()
		for CPU specific initialization. interrupt_init_cpu()
		should set decrementer_count to appropriate value. If
		CPU resets decrementer automatically after interrupt
		(ppc4xx) it should set decrementer_count to zero.
		timer_interrupt() calls timer_interrupt_cpu() for CPU
		specific handling. If board has watchdog / status_led
		/ other_activity_monitor it works automatically from
		general timer_interrupt().


Board initialization settings:
------------------------------

During Initialization u-boot calls a number of board specific functions
to allow the preparation of board specific prerequisites, e.g. pin setup
before drivers are initialized. To enable these callbacks the
following configuration macros have to be defined. Currently this is
architecture specific, so please check arch/your_architecture/lib/board.c
typically in board_init_f() and board_init_r().

- CONFIG_BOARD_EARLY_INIT_F: Call board_early_init_f()
- CONFIG_BOARD_EARLY_INIT_R: Call board_early_init_r()
- CONFIG_BOARD_LATE_INIT: Call board_late_init()
- CONFIG_BOARD_POSTCLK_INIT: Call board_postclk_init()

Configuration Settings:
-----------------------

- CONFIG_SYS_SUPPORT_64BIT_DATA: Defined automatically if compiled as 64-bit.
		Optionally it can be defined to support 64-bit memory commands.

- CONFIG_SYS_LONGHELP: Defined when you want long help messages included;
		undefine this when you're short of memory.

- CONFIG_SYS_HELP_CMD_WIDTH: Defined when you want to override the default
		width of the commands listed in the 'help' command output.

- CONFIG_SYS_PROMPT:	This is what U-Boot prints on the console to
		prompt for user input.

- CONFIG_SYS_CBSIZE:	Buffer size for input from the Console

- CONFIG_SYS_PBSIZE:	Buffer size for Console output

- CONFIG_SYS_MAXARGS:	max. Number of arguments accepted for monitor commands

- CONFIG_SYS_BARGSIZE: Buffer size for Boot Arguments which are passed to
		the application (usually a Linux kernel) when it is
		booted

- CONFIG_SYS_BAUDRATE_TABLE:
		List of legal baudrate settings for this board.

- CONFIG_SYS_MEMTEST_START, CONFIG_SYS_MEMTEST_END:
		Begin and End addresses of the area used by the
		simple memory test.

- CONFIG_SYS_ALT_MEMTEST:
		Enable an alternate, more extensive memory test.

- CONFIG_SYS_MEMTEST_SCRATCH:
		Scratch address used by the alternate memory test
		You only need to set this if address zero isn't writeable

- CONFIG_SYS_MEM_RESERVE_SECURE
		Only implemented for ARMv8 for now.
		If defined, the size of CONFIG_SYS_MEM_RESERVE_SECURE memory
		is substracted from total RAM and won't be reported to OS.
		This memory can be used as secure memory. A variable
		gd->arch.secure_ram is used to track the location. In systems
		the RAM base is not zero, or RAM is divided into banks,
		this variable needs to be recalcuated to get the address.

- CONFIG_SYS_MEM_TOP_HIDE:
		If CONFIG_SYS_MEM_TOP_HIDE is defined in the board config header,
		this specified memory area will get subtracted from the top
		(end) of RAM and won't get "touched" at all by U-Boot. By
		fixing up gd->ram_size the Linux kernel should gets passed
		the now "corrected" memory size and won't touch it either.
		This should work for arch/ppc and arch/powerpc. Only Linux
		board ports in arch/powerpc with bootwrapper support that
		recalculate the memory size from the SDRAM controller setup
		will have to get fixed in Linux additionally.

		This option can be used as a workaround for the 440EPx/GRx
		CHIP 11 errata where the last 256 bytes in SDRAM shouldn't
		be touched.

		WARNING: Please make sure that this value is a multiple of
		the Linux page size (normally 4k). If this is not the case,
		then the end address of the Linux memory will be located at a
		non page size aligned address and this could cause major
		problems.

- CONFIG_SYS_LOADS_BAUD_CHANGE:
		Enable temporary baudrate change while serial download

- CONFIG_SYS_SDRAM_BASE:
		Physical start address of SDRAM. _Must_ be 0 here.

- CONFIG_SYS_FLASH_BASE:
		Physical start address of Flash memory.

- CONFIG_SYS_MONITOR_BASE:
		Physical start address of boot monitor code (set by
		make config files to be same as the text base address
		(CONFIG_SYS_TEXT_BASE) used when linking) - same as
		CONFIG_SYS_FLASH_BASE when booting from flash.

- CONFIG_SYS_MONITOR_LEN:
		Size of memory reserved for monitor code, used to
		determine _at_compile_time_ (!) if the environment is
		embedded within the U-Boot image, or in a separate
		flash sector.

- CONFIG_SYS_MALLOC_LEN:
		Size of DRAM reserved for malloc() use.

- CONFIG_SYS_MALLOC_F_LEN
		Size of the malloc() pool for use before relocation. If
		this is defined, then a very simple malloc() implementation
		will become available before relocation. The address is just
		below the global data, and the stack is moved down to make
		space.

		This feature allocates regions with increasing addresses
		within the region. calloc() is supported, but realloc()
		is not available. free() is supported but does nothing.
		The memory will be freed (or in fact just forgotten) when
		U-Boot relocates itself.

- CONFIG_SYS_MALLOC_SIMPLE
		Provides a simple and small malloc() and calloc() for those
		boards which do not use the full malloc in SPL (which is
		enabled with CONFIG_SYS_SPL_MALLOC_START).

- CONFIG_SYS_NONCACHED_MEMORY:
		Size of non-cached memory area. This area of memory will be
		typically located right below the malloc() area and mapped
		uncached in the MMU. This is useful for drivers that would
		otherwise require a lot of explicit cache maintenance. For
		some drivers it's also impossible to properly maintain the
		cache. For example if the regions that need to be flushed
		are not a multiple of the cache-line size, *and* padding
		cannot be allocated between the regions to align them (i.e.
		if the HW requires a contiguous array of regions, and the
		size of each region is not cache-aligned), then a flush of
		one region may result in overwriting data that hardware has
		written to another region in the same cache-line. This can
		happen for example in network drivers where descriptors for
		buffers are typically smaller than the CPU cache-line (e.g.
		16 bytes vs. 32 or 64 bytes).

		Non-cached memory is only supported on 32-bit ARM at present.

- CONFIG_SYS_BOOTM_LEN:
		Normally compressed uImages are limited to an
		uncompressed size of 8 MBytes. If this is not enough,
		you can define CONFIG_SYS_BOOTM_LEN in your board config file
		to adjust this setting to your needs.

- CONFIG_SYS_BOOTMAPSZ:
		Maximum size of memory mapped by the startup code of
		the Linux kernel; all data that must be processed by
		the Linux kernel (bd_info, boot arguments, FDT blob if
		used) must be put below this limit, unless "bootm_low"
		environment variable is defined and non-zero. In such case
		all data for the Linux kernel must be between "bootm_low"
		and "bootm_low" + CONFIG_SYS_BOOTMAPSZ.	 The environment
		variable "bootm_mapsize" will override the value of
		CONFIG_SYS_BOOTMAPSZ.  If CONFIG_SYS_BOOTMAPSZ is undefined,
		then the value in "bootm_size" will be used instead.

- CONFIG_SYS_BOOT_RAMDISK_HIGH:
		Enable initrd_high functionality.  If defined then the
		initrd_high feature is enabled and the bootm ramdisk subcommand
		is enabled.

- CONFIG_SYS_BOOT_GET_CMDLINE:
		Enables allocating and saving kernel cmdline in space between
		"bootm_low" and "bootm_low" + BOOTMAPSZ.

- CONFIG_SYS_BOOT_GET_KBD:
		Enables allocating and saving a kernel copy of the bd_info in
		space between "bootm_low" and "bootm_low" + BOOTMAPSZ.

- CONFIG_SYS_MAX_FLASH_BANKS:
		Max number of Flash memory banks

- CONFIG_SYS_MAX_FLASH_SECT:
		Max number of sectors on a Flash chip

- CONFIG_SYS_FLASH_ERASE_TOUT:
		Timeout for Flash erase operations (in ms)

- CONFIG_SYS_FLASH_WRITE_TOUT:
		Timeout for Flash write operations (in ms)

- CONFIG_SYS_FLASH_LOCK_TOUT
		Timeout for Flash set sector lock bit operation (in ms)

- CONFIG_SYS_FLASH_UNLOCK_TOUT
		Timeout for Flash clear lock bits operation (in ms)

- CONFIG_SYS_FLASH_PROTECTION
		If defined, hardware flash sectors protection is used
		instead of U-Boot software protection.

- CONFIG_SYS_DIRECT_FLASH_TFTP:

		Enable TFTP transfers directly to flash memory;
		without this option such a download has to be
		performed in two steps: (1) download to RAM, and (2)
		copy from RAM to flash.

		The two-step approach is usually more reliable, since
		you can check if the download worked before you erase
		the flash, but in some situations (when system RAM is
		too limited to allow for a temporary copy of the
		downloaded image) this option may be very useful.

- CONFIG_SYS_FLASH_CFI:
		Define if the flash driver uses extra elements in the
		common flash structure for storing flash geometry.

- CONFIG_FLASH_CFI_DRIVER
		This option also enables the building of the cfi_flash driver
		in the drivers directory

- CONFIG_FLASH_CFI_MTD
		This option enables the building of the cfi_mtd driver
		in the drivers directory. The driver exports CFI flash
		to the MTD layer.

- CONFIG_SYS_FLASH_USE_BUFFER_WRITE
		Use buffered writes to flash.

- CONFIG_FLASH_SPANSION_S29WS_N
		s29ws-n MirrorBit flash has non-standard addresses for buffered
		write commands.

- CONFIG_SYS_FLASH_QUIET_TEST
		If this option is defined, the common CFI flash doesn't
		print it's warning upon not recognized FLASH banks. This
		is useful, if some of the configured banks are only
		optionally available.

- CONFIG_FLASH_SHOW_PROGRESS
		If defined (must be an integer), print out countdown
		digits and dots.  Recommended value: 45 (9..1) for 80
		column displays, 15 (3..1) for 40 column displays.

- CONFIG_FLASH_VERIFY
		If defined, the content of the flash (destination) is compared
		against the source after the write operation. An error message
		will be printed when the contents are not identical.
		Please note that this option is useless in nearly all cases,
		since such flash programming errors usually are detected earlier
		while unprotecting/erasing/programming. Please only enable
		this option if you really know what you are doing.

- CONFIG_SYS_RX_ETH_BUFFER:
		Defines the number of Ethernet receive buffers. On some
		Ethernet controllers it is recommended to set this value
		to 8 or even higher (EEPRO100 or 405 EMAC), since all
		buffers can be full shortly after enabling the interface
		on high Ethernet traffic.
		Defaults to 4 if not defined.

- CONFIG_ENV_MAX_ENTRIES

	Maximum number of entries in the hash table that is used
	internally to store the environment settings. The default
	setting is supposed to be generous and should work in most
	cases. This setting can be used to tune behaviour; see
	lib/hashtable.c for details.

- CONFIG_ENV_FLAGS_LIST_DEFAULT
- CONFIG_ENV_FLAGS_LIST_STATIC
	Enable validation of the values given to environment variables when
	calling env set.  Variables can be restricted to only decimal,
	hexadecimal, or boolean.  If CONFIG_CMD_NET is also defined,
	the variables can also be restricted to IP address or MAC address.

	The format of the list is:
		type_attribute = [s|d|x|b|i|m]
		access_attribute = [a|r|o|c]
		attributes = type_attribute[access_attribute]
		entry = variable_name[:attributes]
		list = entry[,list]

	The type attributes are:
		s - String (default)
		d - Decimal
		x - Hexadecimal
		b - Boolean ([1yYtT|0nNfF])
		i - IP address
		m - MAC address

	The access attributes are:
		a - Any (default)
		r - Read-only
		o - Write-once
		c - Change-default

	- CONFIG_ENV_FLAGS_LIST_DEFAULT
		Define this to a list (string) to define the ".flags"
		environment variable in the default or embedded environment.

	- CONFIG_ENV_FLAGS_LIST_STATIC
		Define this to a list (string) to define validation that
		should be done if an entry is not found in the ".flags"
		environment variable.  To override a setting in the static
		list, simply add an entry for the same variable name to the
		".flags" variable.

	If CONFIG_REGEX is defined, the variable_name above is evaluated as a
	regular expression. This allows multiple variables to define the same
	flags without explicitly listing them for each variable.

- CONFIG_ENV_ACCESS_IGNORE_FORCE
	If defined, don't allow the -f switch to env set override variable
	access flags.

- CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC (OMAP only)
	This is set by OMAP boards for the max time that reset should
	be asserted. See doc/README.omap-reset-time for details on how
	the value can be calculated on a given board.

- CONFIG_USE_STDINT
	If stdint.h is available with your toolchain you can define this
	option to enable it. You can provide option 'USE_STDINT=1' when
	building U-Boot to enable this.

The following definitions that deal with the placement and management
of environment data (variable area); in general, we support the
following configurations:

- CONFIG_BUILD_ENVCRC:

	Builds up envcrc with the target environment so that external utils
	may easily extract it and embed it in final U-Boot images.

- CONFIG_ENV_IS_IN_FLASH:

	Define this if the environment is in flash memory.

	a) The environment occupies one whole flash sector, which is
	   "embedded" in the text segment with the U-Boot code. This
	   happens usually with "bottom boot sector" or "top boot
	   sector" type flash chips, which have several smaller
	   sectors at the start or the end. For instance, such a
	   layout can have sector sizes of 8, 2x4, 16, Nx32 kB. In
	   such a case you would place the environment in one of the
	   4 kB sectors - with U-Boot code before and after it. With
	   "top boot sector" type flash chips, you would put the
	   environment in one of the last sectors, leaving a gap
	   between U-Boot and the environment.

	- CONFIG_ENV_OFFSET:

	   Offset of environment data (variable area) to the
	   beginning of flash memory; for instance, with bottom boot
	   type flash chips the second sector can be used: the offset
	   for this sector is given here.

	   CONFIG_ENV_OFFSET is used relative to CONFIG_SYS_FLASH_BASE.

	- CONFIG_ENV_ADDR:

	   This is just another way to specify the start address of
	   the flash sector containing the environment (instead of
	   CONFIG_ENV_OFFSET).

	- CONFIG_ENV_SECT_SIZE:

	   Size of the sector containing the environment.


	b) Sometimes flash chips have few, equal sized, BIG sectors.
	   In such a case you don't want to spend a whole sector for
	   the environment.

	- CONFIG_ENV_SIZE:

	   If you use this in combination with CONFIG_ENV_IS_IN_FLASH
	   and CONFIG_ENV_SECT_SIZE, you can specify to use only a part
	   of this flash sector for the environment. This saves
	   memory for the RAM copy of the environment.

	   It may also save flash memory if you decide to use this
	   when your environment is "embedded" within U-Boot code,
	   since then the remainder of the flash sector could be used
	   for U-Boot code. It should be pointed out that this is
	   STRONGLY DISCOURAGED from a robustness point of view:
	   updating the environment in flash makes it always
	   necessary to erase the WHOLE sector. If something goes
	   wrong before the contents has been restored from a copy in
	   RAM, your target system will be dead.

	- CONFIG_ENV_ADDR_REDUND
	  CONFIG_ENV_SIZE_REDUND

	   These settings describe a second storage area used to hold
	   a redundant copy of the environment data, so that there is
	   a valid backup copy in case there is a power failure during
	   a "saveenv" operation.

BE CAREFUL! Any changes to the flash layout, and some changes to the
source code will make it necessary to adapt <board>/u-boot.lds*
accordingly!


- CONFIG_ENV_IS_IN_NVRAM:

	Define this if you have some non-volatile memory device
	(NVRAM, battery buffered SRAM) which you want to use for the
	environment.

	- CONFIG_ENV_ADDR:
	- CONFIG_ENV_SIZE:

	  These two #defines are used to determine the memory area you
	  want to use for environment. It is assumed that this memory
	  can just be read and written to, without any special
	  provision.

BE CAREFUL! The first access to the environment happens quite early
in U-Boot initialization (when we try to get the setting of for the
console baudrate). You *MUST* have mapped your NVRAM area then, or
U-Boot will hang.

Please note that even with NVRAM we still use a copy of the
environment in RAM: we could work on NVRAM directly, but we want to
keep settings there always unmodified except somebody uses "saveenv"
to save the current settings.


- CONFIG_ENV_IS_IN_EEPROM:

	Use this if you have an EEPROM or similar serial access
	device and a driver for it.

	- CONFIG_ENV_OFFSET:
	- CONFIG_ENV_SIZE:

	  These two #defines specify the offset and size of the
	  environment area within the total memory of your EEPROM.

	- CONFIG_SYS_I2C_EEPROM_ADDR:
	  If defined, specified the chip address of the EEPROM device.
	  The default address is zero.

	- CONFIG_SYS_I2C_EEPROM_BUS:
	  If defined, specified the i2c bus of the EEPROM device.

	- CONFIG_SYS_EEPROM_PAGE_WRITE_BITS:
	  If defined, the number of bits used to address bytes in a
	  single page in the EEPROM device.  A 64 byte page, for example
	  would require six bits.

	- CONFIG_SYS_EEPROM_PAGE_WRITE_DELAY_MS:
	  If defined, the number of milliseconds to delay between
	  page writes.	The default is zero milliseconds.

	- CONFIG_SYS_I2C_EEPROM_ADDR_LEN:
	  The length in bytes of the EEPROM memory array address.  Note
	  that this is NOT the chip address length!

	- CONFIG_SYS_I2C_EEPROM_ADDR_OVERFLOW:
	  EEPROM chips that implement "address overflow" are ones
	  like Catalyst 24WC04/08/16 which has 9/10/11 bits of
	  address and the extra bits end up in the "chip address" bit
	  slots. This makes a 24WC08 (1Kbyte) chip look like four 256
	  byte chips.

	  Note that we consider the length of the address field to
	  still be one byte because the extra address bits are hidden
	  in the chip address.

	- CONFIG_SYS_EEPROM_SIZE:
	  The size in bytes of the EEPROM device.

	- CONFIG_ENV_EEPROM_IS_ON_I2C
	  define this, if you have I2C and SPI activated, and your
	  EEPROM, which holds the environment, is on the I2C bus.

	- CONFIG_I2C_ENV_EEPROM_BUS
	  if you have an Environment on an EEPROM reached over
	  I2C muxes, you can define here, how to reach this
	  EEPROM. For example:

	  #define CONFIG_I2C_ENV_EEPROM_BUS	  1

	  EEPROM which holds the environment, is reached over
	  a pca9547 i2c mux with address 0x70, channel 3.

- CONFIG_ENV_IS_IN_DATAFLASH:

	Define this if you have a DataFlash memory device which you
	want to use for the environment.

	- CONFIG_ENV_OFFSET:
	- CONFIG_ENV_ADDR:
	- CONFIG_ENV_SIZE:

	  These three #defines specify the offset and size of the
	  environment area within the total memory of your DataFlash placed
	  at the specified address.

- CONFIG_ENV_IS_IN_SPI_FLASH:

	Define this if you have a SPI Flash memory device which you
	want to use for the environment.

	- CONFIG_ENV_OFFSET:
	- CONFIG_ENV_SIZE:

	  These two #defines specify the offset and size of the
	  environment area within the SPI Flash. CONFIG_ENV_OFFSET must be
	  aligned to an erase sector boundary.

	- CONFIG_ENV_SECT_SIZE:

	  Define the SPI flash's sector size.

	- CONFIG_ENV_OFFSET_REDUND (optional):

	  This setting describes a second storage area of CONFIG_ENV_SIZE
	  size used to hold a redundant copy of the environment data, so
	  that there is a valid backup copy in case there is a power failure
	  during a "saveenv" operation. CONFIG_ENV_OFFSET_REDUND must be
	  aligned to an erase sector boundary.

	- CONFIG_ENV_SPI_BUS (optional):
	- CONFIG_ENV_SPI_CS (optional):

	  Define the SPI bus and chip select. If not defined they will be 0.

	- CONFIG_ENV_SPI_MAX_HZ (optional):

	  Define the SPI max work clock. If not defined then use 1MHz.

	- CONFIG_ENV_SPI_MODE (optional):

	  Define the SPI work mode. If not defined then use SPI_MODE_3.

- CONFIG_ENV_IS_IN_REMOTE:

	Define this if you have a remote memory space which you
	want to use for the local device's environment.

	- CONFIG_ENV_ADDR:
	- CONFIG_ENV_SIZE:

	  These two #defines specify the address and size of the
	  environment area within the remote memory space. The
	  local device can get the environment from remote memory
	  space by SRIO or PCIE links.

BE CAREFUL! For some special cases, the local device can not use
"saveenv" command. For example, the local device will get the
environment stored in a remote NOR flash by SRIO or PCIE link,
but it can not erase, write this NOR flash by SRIO or PCIE interface.

- CONFIG_ENV_IS_IN_NAND:

	Define this if you have a NAND device which you want to use
	for the environment.

	- CONFIG_ENV_OFFSET:
	- CONFIG_ENV_SIZE:

	  These two #defines specify the offset and size of the environment
	  area within the first NAND device.  CONFIG_ENV_OFFSET must be
	  aligned to an erase block boundary.

	- CONFIG_ENV_OFFSET_REDUND (optional):

	  This setting describes a second storage area of CONFIG_ENV_SIZE
	  size used to hold a redundant copy of the environment data, so
	  that there is a valid backup copy in case there is a power failure
	  during a "saveenv" operation.	 CONFIG_ENV_OFFSET_REDUND must be
	  aligned to an erase block boundary.

	- CONFIG_ENV_RANGE (optional):

	  Specifies the length of the region in which the environment
	  can be written.  This should be a multiple of the NAND device's
	  block size.  Specifying a range with more erase blocks than
	  are needed to hold CONFIG_ENV_SIZE allows bad blocks within
	  the range to be avoided.

	- CONFIG_ENV_OFFSET_OOB (optional):

	  Enables support for dynamically retrieving the offset of the
	  environment from block zero's out-of-band data.  The
	  "nand env.oob" command can be used to record this offset.
	  Currently, CONFIG_ENV_OFFSET_REDUND is not supported when
	  using CONFIG_ENV_OFFSET_OOB.

- CONFIG_NAND_ENV_DST

	Defines address in RAM to which the nand_spl code should copy the
	environment. If redundant environment is used, it will be copied to
	CONFIG_NAND_ENV_DST + CONFIG_ENV_SIZE.

- CONFIG_ENV_IS_IN_UBI:

	Define this if you have an UBI volume that you want to use for the
	environment.  This has the benefit of wear-leveling the environment
	accesses, which is important on NAND.

	- CONFIG_ENV_UBI_PART:

	  Define this to a string that is the mtd partition containing the UBI.

	- CONFIG_ENV_UBI_VOLUME:

	  Define this to the name of the volume that you want to store the