README

	   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.

	- CFG_ENV_ADDR_REDUND
	  CFG_ENV_SIZE_REDUND

	   These settings describe a second storage area used to hold
	   a redundand 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!


- CFG_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.

	- CFG_ENV_ADDR:
	- CFG_ENV_SIZE:

	  These two #defines are used to determin 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 initalization (when we try to get the setting of for the
console baudrate). You *MUST* have mappend 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.


- CFG_ENV_IS_IN_EEPROM:

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

	- CFG_ENV_OFFSET:
	- CFG_ENV_SIZE:

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

	- CFG_I2C_EEPROM_ADDR:
	  If defined, specified the chip address of the EEPROM device.
	  The default address is zero.

	- CFG_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.

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

	- CFG_I2C_EEPROM_ADDR_LEN:
	  The length in bytes of the EEPROM memory array address.  Note
	  that this is NOT the chip address length!

	- CFG_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.

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


- CFG_ENV_IS_IN_DATAFLASH:

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

	- CFG_ENV_OFFSET:
	- CFG_ENV_ADDR:
	- CFG_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.

- CFG_ENV_IS_IN_NAND:

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

	- CFG_ENV_OFFSET:
	- CFG_ENV_SIZE:

	  These two #defines specify the offset and size of the environment
	  area within the first NAND device.

	- CFG_ENV_OFFSET_REDUND

	  This setting describes a second storage area of CFG_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.

	Note: CFG_ENV_OFFSET and CFG_ENV_OFFSET_REDUND must be aligned
	to a block boundary, and CFG_ENV_SIZE must be a multiple of
	the NAND devices block size.

- CFG_SPI_INIT_OFFSET

	Defines offset to the initial SPI buffer area in DPRAM. The
	area is used at an early stage (ROM part) if the environment
	is configured to reside in the SPI EEPROM: We need a 520 byte
	scratch DPRAM area. It is used between the two initialization
	calls (spi_init_f() and spi_init_r()). A value of 0xB00 seems
	to be a good choice since it makes it far enough from the
	start of the data area as well as from the stack pointer.

Please note that the environment is read-only until the monitor
has been relocated to RAM and a RAM copy of the environment has been
created; also, when using EEPROM you will have to use getenv_r()
until then to read environment variables.

The environment is protected by a CRC32 checksum. Before the monitor
is relocated into RAM, as a result of a bad CRC you will be working
with the compiled-in default environment - *silently*!!! [This is
necessary, because the first environment variable we need is the
"baudrate" setting for the console - if we have a bad CRC, we don't
have any device yet where we could complain.]

Note: once the monitor has been relocated, then it will complain if
the default environment is used; a new CRC is computed as soon as you
use the "saveenv" command to store a valid environment.

- CFG_FAULT_ECHO_LINK_DOWN:
		Echo the inverted Ethernet link state to the fault LED.

		Note: If this option is active, then CFG_FAULT_MII_ADDR
		      also needs to be defined.

- CFG_FAULT_MII_ADDR:
		MII address of the PHY to check for the Ethernet link state.

- CFG_64BIT_VSPRINTF:
		Makes vsprintf (and all *printf functions) support printing
		of 64bit values by using the L quantifier

- CFG_64BIT_STRTOUL:
		Adds simple_strtoull that returns a 64bit value

Low Level (hardware related) configuration options:
---------------------------------------------------

- CFG_CACHELINE_SIZE:
		Cache Line Size of the CPU.

- CFG_DEFAULT_IMMR:
		Default address of the IMMR after system reset.

		Needed on some 8260 systems (MPC8260ADS, PQ2FADS-ZU,
		and RPXsuper) to be able to adjust the position of
		the IMMR register after a reset.

- Floppy Disk Support:
		CFG_FDC_DRIVE_NUMBER

		the default drive number (default value 0)

		CFG_ISA_IO_STRIDE

		defines the spacing between fdc chipset registers
		(default value 1)

		CFG_ISA_IO_OFFSET

		defines the offset of register from address. It
		depends on which part of the data bus is connected to
		the fdc chipset. (default value 0)

		If CFG_ISA_IO_STRIDE CFG_ISA_IO_OFFSET and
		CFG_FDC_DRIVE_NUMBER are undefined, they take their
		default value.

		if CFG_FDC_HW_INIT is defined, then the function
		fdc_hw_init() is called at the beginning of the FDC
		setup. fdc_hw_init() must be provided by the board
		source code. It is used to make hardware dependant
		initializations.

- CFG_IMMR:	Physical address of the Internal Memory.
		DO NOT CHANGE unless you know exactly what you're
		doing! (11-4) [MPC8xx/82xx systems only]

- CFG_INIT_RAM_ADDR:

		Start address of memory area that can be used for
		initial data and stack; please note that this must be
		writable memory that is working WITHOUT special
		initialization, i. e. you CANNOT use normal RAM which
		will become available only after programming the
		memory controller and running certain initialization
		sequences.

		U-Boot uses the following memory types:
		- MPC8xx and MPC8260: IMMR (internal memory of the CPU)
		- MPC824X: data cache
		- PPC4xx:  data cache

- CFG_GBL_DATA_OFFSET:

		Offset of the initial data structure in the memory
		area defined by CFG_INIT_RAM_ADDR. Usually
		CFG_GBL_DATA_OFFSET is chosen such that the initial
		data is located at the end of the available space
		(sometimes written as (CFG_INIT_RAM_END -
		CFG_INIT_DATA_SIZE), and the initial stack is just
		below that area (growing from (CFG_INIT_RAM_ADDR +
		CFG_GBL_DATA_OFFSET) downward.

	Note:
		On the MPC824X (or other systems that use the data
		cache for initial memory) the address chosen for
		CFG_INIT_RAM_ADDR is basically arbitrary - it must
		point to an otherwise UNUSED address space between
		the top of RAM and the start of the PCI space.

- CFG_SIUMCR:	SIU Module Configuration (11-6)

- CFG_SYPCR:	System Protection Control (11-9)

- CFG_TBSCR:	Time Base Status and Control (11-26)

- CFG_PISCR:	Periodic Interrupt Status and Control (11-31)

- CFG_PLPRCR:	PLL, Low-Power, and Reset Control Register (15-30)

- CFG_SCCR:	System Clock and reset Control Register (15-27)

- CFG_OR_TIMING_SDRAM:
		SDRAM timing

- CFG_MAMR_PTA:
		periodic timer for refresh

- CFG_DER:	Debug Event Register (37-47)

- FLASH_BASE0_PRELIM, FLASH_BASE1_PRELIM, CFG_REMAP_OR_AM,
  CFG_PRELIM_OR_AM, CFG_OR_TIMING_FLASH, CFG_OR0_REMAP,
  CFG_OR0_PRELIM, CFG_BR0_PRELIM, CFG_OR1_REMAP, CFG_OR1_PRELIM,
  CFG_BR1_PRELIM:
		Memory Controller Definitions: BR0/1 and OR0/1 (FLASH)

- SDRAM_BASE2_PRELIM, SDRAM_BASE3_PRELIM, SDRAM_MAX_SIZE,
  CFG_OR_TIMING_SDRAM, CFG_OR2_PRELIM, CFG_BR2_PRELIM,
  CFG_OR3_PRELIM, CFG_BR3_PRELIM:
		Memory Controller Definitions: BR2/3 and OR2/3 (SDRAM)

- CFG_MAMR_PTA, CFG_MPTPR_2BK_4K, CFG_MPTPR_1BK_4K, CFG_MPTPR_2BK_8K,
  CFG_MPTPR_1BK_8K, CFG_MAMR_8COL, CFG_MAMR_9COL:
		Machine Mode Register and Memory Periodic Timer
		Prescaler definitions (SDRAM timing)

- CFG_I2C_UCODE_PATCH, CFG_I2C_DPMEM_OFFSET [0x1FC0]:
		enable I2C microcode relocation patch (MPC8xx);
		define relocation offset in DPRAM [DSP2]

- CFG_SPI_UCODE_PATCH, CFG_SPI_DPMEM_OFFSET [0x1FC0]:
		enable SPI microcode relocation patch (MPC8xx);
		define relocation offset in DPRAM [SCC4]

- CFG_USE_OSCCLK:
		Use OSCM clock mode on MBX8xx board. Be careful,
		wrong setting might damage your board. Read
		doc/README.MBX before setting this variable!

- CFG_CPM_POST_WORD_ADDR: (MPC8xx, MPC8260 only)
		Offset of the bootmode word in DPRAM used by post
		(Power On Self Tests). This definition overrides
		#define'd default value in commproc.h resp.
		cpm_8260.h.

- CFG_PCI_SLV_MEM_LOCAL, CFG_PCI_SLV_MEM_BUS, CFG_PICMR0_MASK_ATTRIB,
  CFG_PCI_MSTR0_LOCAL, CFG_PCIMSK0_MASK, CFG_PCI_MSTR1_LOCAL,
  CFG_PCIMSK1_MASK, CFG_PCI_MSTR_MEM_LOCAL, CFG_PCI_MSTR_MEM_BUS,
  CFG_CPU_PCI_MEM_START, CFG_PCI_MSTR_MEM_SIZE, CFG_POCMR0_MASK_ATTRIB,
  CFG_PCI_MSTR_MEMIO_LOCAL, CFG_PCI_MSTR_MEMIO_BUS, CPU_PCI_MEMIO_START,
  CFG_PCI_MSTR_MEMIO_SIZE, CFG_POCMR1_MASK_ATTRIB, CFG_PCI_MSTR_IO_LOCAL,
  CFG_PCI_MSTR_IO_BUS, CFG_CPU_PCI_IO_START, CFG_PCI_MSTR_IO_SIZE,
  CFG_POCMR2_MASK_ATTRIB: (MPC826x only)
		Overrides the default PCI memory map in cpu/mpc8260/pci.c if set.

- CONFIG_SPD_EEPROM
		Get DDR timing information from an I2C EEPROM.  Common with pluggable
		memory modules such as SODIMMs
  SPD_EEPROM_ADDRESS
		I2C address of the SPD EEPROM

- CFG_SPD_BUS_NUM
		If SPD EEPROM is on an I2C bus other than the first one, specify here.
		Note that the value must resolve to something your driver can deal with.

- CFG_83XX_DDR_USES_CS0
		Only for 83xx systems. If specified, then DDR should be configured
		using CS0 and CS1 instead of CS2 and CS3.

- CFG_83XX_DDR_USES_CS0
		Only for 83xx systems. If specified, then DDR should be configured
		using CS0 and CS1 instead of CS2 and CS3.

- CONFIG_ETHER_ON_FEC[12]
		Define to enable FEC[12] on a 8xx series processor.

- CONFIG_FEC[12]_PHY
		Define to the hardcoded PHY address which corresponds
		to the given FEC; i. e.
			#define CONFIG_FEC1_PHY 4
		means that the PHY with address 4 is connected to FEC1

		When set to -1, means to probe for first available.

- CONFIG_FEC[12]_PHY_NORXERR
		The PHY does not have a RXERR line (RMII only).
		(so program the FEC to ignore it).

- CONFIG_RMII
		Enable RMII mode for all FECs.
		Note that this is a global option, we can't
		have one FEC in standard MII mode and another in RMII mode.

- CONFIG_CRC32_VERIFY
		Add a verify option to the crc32 command.
		The syntax is:

		=> crc32 -v <address> <count> <crc32>

		Where address/count indicate a memory area
		and crc32 is the correct crc32 which the
		area should have.

- CONFIG_LOOPW
		Add the "loopw" memory command. This only takes effect if
		the memory commands are activated globally (CONFIG_CMD_MEM).

- CONFIG_MX_CYCLIC
		Add the "mdc" and "mwc" memory commands. These are cyclic
		"md/mw" commands.
		Examples:

		=> mdc.b 10 4 500
		This command will print 4 bytes (10,11,12,13) each 500 ms.

		=> mwc.l 100 12345678 10
		This command will write 12345678 to address 100 all 10 ms.

		This only takes effect if the memory commands are activated
		globally (CONFIG_CMD_MEM).

- CONFIG_SKIP_LOWLEVEL_INIT
- CONFIG_SKIP_RELOCATE_UBOOT

		[ARM only] If these variables are defined, then
		certain low level initializations (like setting up
		the memory controller) are omitted and/or U-Boot does
		not relocate itself into RAM.
		Normally these variables MUST NOT be defined. The
		only exception is when U-Boot is loaded (to RAM) by
		some other boot loader or by a debugger which
		performs these intializations itself.


Building the Software:
======================

Building U-Boot has been tested in native PPC environments (on a
PowerBook G3 running LinuxPPC 2000) and in cross environments
(running RedHat 6.x and 7.x Linux on x86, Solaris 2.6 on a SPARC, and
NetBSD 1.5 on x86).

If you are not using a native PPC environment, it is assumed that you
have the GNU cross compiling tools available in your path and named
with a prefix of "powerpc-linux-". If this is not the case, (e.g. if
you are using Monta Vista's Hard Hat Linux CDK 1.2) you must change
the definition of CROSS_COMPILE in Makefile. For HHL on a 4xx CPU,
change it to:

	CROSS_COMPILE = ppc_4xx-


U-Boot is intended to be  simple  to  build.  After  installing	 the
sources	 you must configure U-Boot for one specific board type. This
is done by typing:

	make NAME_config

where "NAME_config" is the name of one of the existing
configurations; see the main Makefile for supported names.

Note: for some board special configuration names may exist; check if
      additional information is available from the board vendor; for
      instance, the TQM823L systems are available without (standard)
      or with LCD support. You can select such additional "features"
      when chosing the configuration, i. e.

      make TQM823L_config
	- will configure for a plain TQM823L, i. e. no LCD support

      make TQM823L_LCD_config
	- will configure for a TQM823L with U-Boot console on LCD

      etc.


Finally, type "make all", and you should get some working U-Boot
images ready for download to / installation on your system:

- "u-boot.bin" is a raw binary image
- "u-boot" is an image in ELF binary format
- "u-boot.srec" is in Motorola S-Record format

By default the build is performed locally and the objects are saved
in the source directory. One of the two methods can be used to change
this behavior and build U-Boot to some external directory:

1. Add O= to the make command line invocations:

	make O=/tmp/build distclean
	make O=/tmp/build NAME_config
	make O=/tmp/build all

2. Set environment variable BUILD_DIR to point to the desired location:

	export BUILD_DIR=/tmp/build
	make distclean
	make NAME_config
	make all

Note that the command line "O=" setting overrides the BUILD_DIR environment
variable.


Please be aware that the Makefiles assume you are using GNU make, so
for instance on NetBSD you might need to use "gmake" instead of
native "make".


If the system board that you have is not listed, then you will need
to port U-Boot to your hardware platform. To do this, follow these
steps:

1.  Add a new configuration option for your board to the toplevel
    "Makefile" and to the "MAKEALL" script, using the existing
    entries as examples. Note that here and at many other places
    boards and other names are listed in alphabetical sort order. Please
    keep this order.
2.  Create a new directory to hold your board specific code. Add any
    files you need. In your board directory, you will need at least
    the "Makefile", a "<board>.c", "flash.c" and "u-boot.lds".
3.  Create a new configuration file "include/configs/<board>.h" for
    your board
3.  If you're porting U-Boot to a new CPU, then also create a new
    directory to hold your CPU specific code. Add any files you need.
4.  Run "make <board>_config" with your new name.
5.  Type "make", and you should get a working "u-boot.srec" file
    to be installed on your target system.
6.  Debug and solve any problems that might arise.
    [Of course, this last step is much harder than it sounds.]


Testing of U-Boot Modifications, Ports to New Hardware, etc.:
==============================================================

If you have modified U-Boot sources (for instance added a new	board
or  support  for  new  devices,	 a new CPU, etc.) you are expected to
provide feedback to the other developers. The feedback normally takes
the form of a "patch", i. e. a context diff against a certain (latest
official or latest in CVS) version of U-Boot sources.

But before you submit such a patch, please verify that	your  modifi-
cation	did not break existing code. At least make sure that *ALL* of
the supported boards compile WITHOUT ANY compiler warnings. To do so,
just run the "MAKEALL" script, which will configure and build U-Boot
for ALL supported system. Be warned, this will take a while. You  can
select	which  (cross)	compiler  to use by passing a `CROSS_COMPILE'
environment variable to the script, i. e. to use the cross tools from
MontaVista's Hard Hat Linux you can type

	CROSS_COMPILE=ppc_8xx- MAKEALL

or to build on a native PowerPC system you can type

	CROSS_COMPILE=' ' MAKEALL

When using the MAKEALL script, the default behaviour is to build U-Boot
in the source directory. This location can be changed by setting the
BUILD_DIR environment variable. Also, for each target built, the MAKEALL
script saves two log files (<target>.ERR and <target>.MAKEALL) in the
<source dir>/LOG directory. This default location can be changed by
setting the MAKEALL_LOGDIR environment variable. For example:

	export BUILD_DIR=/tmp/build
	export MAKEALL_LOGDIR=/tmp/log
	CROSS_COMPILE=ppc_8xx- MAKEALL

With the above settings build objects are saved in the /tmp/build, log
files are saved in the /tmp/log and the source tree remains clean during
the whole build process.


See also "U-Boot Porting Guide" below.


Monitor Commands - Overview:
============================

go	- start application at address 'addr'
run	- run commands in an environment variable
bootm	- boot application image from memory
bootp	- boot image via network using BootP/TFTP protocol
tftpboot- boot image via network using TFTP protocol
	       and env variables "ipaddr" and "serverip"
	       (and eventually "gatewayip")
rarpboot- boot image via network using RARP/TFTP protocol
diskboot- boot from IDE devicebootd   - boot default, i.e., run 'bootcmd'
loads	- load S-Record file over serial line
loadb	- load binary file over serial line (kermit mode)
md	- memory display
mm	- memory modify (auto-incrementing)
nm	- memory modify (constant address)
mw	- memory write (fill)
cp	- memory copy
cmp	- memory compare
crc32	- checksum calculation
imd	- i2c memory display
imm	- i2c memory modify (auto-incrementing)
inm	- i2c memory modify (constant address)
imw	- i2c memory write (fill)
icrc32	- i2c checksum calculation
iprobe	- probe to discover valid I2C chip addresses
iloop	- infinite loop on address range
isdram	- print SDRAM configuration information
sspi	- SPI utility commands
base	- print or set address offset
printenv- print environment variables
setenv	- set environment variables
saveenv - save environment variables to persistent storage
protect - enable or disable FLASH write protection
erase	- erase FLASH memory
flinfo	- print FLASH memory information
bdinfo	- print Board Info structure
iminfo	- print header information for application image
coninfo - print console devices and informations
ide	- IDE sub-system
loop	- infinite loop on address range
loopw	- infinite write loop on address range
mtest	- simple RAM test
icache	- enable or disable instruction cache
dcache	- enable or disable data cache
reset	- Perform RESET of the CPU
echo	- echo args to console
version - print monitor version
help	- print online help
?	- alias for 'help'


Monitor Commands - Detailed Description:
========================================

TODO.

For now: just type "help <command>".


Environment Variables:
======================

U-Boot supports user configuration using Environment Variables which
can be made persistent by saving to Flash memory.

Environment Variables are set using "setenv", printed using
"printenv", and saved to Flash using "saveenv". Using "setenv"
without a value can be used to delete a variable from the
environment. As long as you don't save the environment you are
working with an in-memory copy. In case the Flash area containing the
environment is erased by accident, a default environment is provided.

Some configuration options can be set using Environment Variables:

  baudrate	- see CONFIG_BAUDRATE

  bootdelay	- see CONFIG_BOOTDELAY

  bootcmd	- see CONFIG_BOOTCOMMAND

  bootargs	- Boot arguments when booting an RTOS image

  bootfile	- Name of the image to load with TFTP

  autoload	- if set to "no" (any string beginning with 'n'),
		  "bootp" will just load perform a lookup of the
		  configuration from the BOOTP server, but not try to
		  load any image using TFTP

  autostart	- if set to "yes", an image loaded using the "bootp",
		  "rarpboot", "tftpboot" or "diskboot" commands will
		  be automatically started (by internally calling
		  "bootm")

		  If set to "no", a standalone image passed to the
		  "bootm" command will be copied to the load address
		  (and eventually uncompressed), but NOT be started.
		  This can be used to load and uncompress arbitrary
		  data.

  i2cfast	- (PPC405GP|PPC405EP only)
		  if set to 'y' configures Linux I2C driver for fast
		  mode (400kHZ). This environment variable is used in
		  initialization code. So, for changes to be effective
		  it must be saved and board must be reset.

  initrd_high	- restrict positioning of initrd images:
		  If this variable is not set, initrd images will be
		  copied to the highest possible address in RAM; this
		  is usually what you want since it allows for
		  maximum initrd size. If for some reason you want to
		  make sure that the initrd image is loaded below the
		  CFG_BOOTMAPSZ limit, you can set this environment
		  variable to a value of "no" or "off" or "0".
		  Alternatively, you can set it to a maximum upper
		  address to use (U-Boot will still check that it
		  does not overwrite the U-Boot stack and data).

		  For instance, when you have a system with 16 MB
		  RAM, and want to reserve 4 MB from use by Linux,
		  you can do this by adding "mem=12M" to the value of
		  the "bootargs" variable. However, now you must make
		  sure that the initrd image is placed in the first
		  12 MB as well - this can be done with

		  setenv initrd_high 00c00000

		  If you set initrd_high to 0xFFFFFFFF, this is an
		  indication to U-Boot that all addresses are legal
		  for the Linux kernel, including addresses in flash
		  memory. In this case U-Boot will NOT COPY the
		  ramdisk at all. This may be useful to reduce the
		  boot time on your system, but requires that this
		  feature is supported by your Linux kernel.

  ipaddr	- IP address; needed for tftpboot command

  loadaddr	- Default load address for commands like "bootp",
		  "rarpboot", "tftpboot", "loadb" or "diskboot"

  loads_echo	- see CONFIG_LOADS_ECHO

  serverip	- TFTP server IP address; needed for tftpboot command

  bootretry	- see CONFIG_BOOT_RETRY_TIME

  bootdelaykey	- see CONFIG_AUTOBOOT_DELAY_STR

  bootstopkey	- see CONFIG_AUTOBOOT_STOP_STR

  ethprime	- When CONFIG_NET_MULTI is enabled controls which
		  interface is used first.

  ethact	- When CONFIG_NET_MULTI is enabled controls which
		  interface is currently active. For example you
		  can do the following

		  => setenv ethact FEC ETHERNET
		  => ping 192.168.0.1 # traffic sent on FEC ETHERNET
		  => setenv ethact SCC ETHERNET
		  => ping 10.0.0.1 # traffic sent on SCC ETHERNET

   netretry	- When set to "no" each network operation will
		  either succeed or fail without retrying.
		  When set to "once" the network operation will
		  fail when all the available network interfaces
		  are tried once without success.
		  Useful on scripts which control the retry operation
		  themselves.

  tftpsrcport	- If this is set, the value is used for TFTP's
		  UDP source port.

  tftpdstport	- If this is set, the value is used for TFTP's UDP
		  destination port instead of the Well Know Port 69.

   vlan		- When set to a value < 4095 the traffic over
		  ethernet is encapsulated/received over 802.1q
		  VLAN tagged frames.

The following environment variables may be used and automatically
updated by the network boot commands ("bootp" and "rarpboot"),
depending the information provided by your boot server:

  bootfile	- see above
  dnsip		- IP address of your Domain Name Server
  dnsip2	- IP address of your secondary Domain Name Server
  gatewayip	- IP address of the Gateway (Router) to use
  hostname	- Target hostname
  ipaddr	- see above
  netmask	- Subnet Mask
  rootpath	- Pathname of the root filesystem on the NFS server
  serverip	- see above


There are two special Environment Variables:

  serial#	- contains hardware identification information such
		  as type string and/or serial number
  ethaddr	- Ethernet address

These variables can be set only once (usually during manufacturing of
the board). U-Boot refuses to delete or overwrite these variables
once they have been set once.


Further special Environment Variables:

  ver		- Contains the U-Boot version string as printed
		  with the "version" command. This variable is
		  readonly (see CONFIG_VERSION_VARIABLE).


Please note that changes to some configuration parameters may take
only effect after the next boot (yes, that's just like Windoze :-).


Command Line Parsing:
=====================

There are two different command line parsers available with U-Boot:
the old "simple" one, and the much more powerful "hush" shell:

Old, simple command line parser:
--------------------------------

- supports environment variables (through setenv / saveenv commands)
- several commands on one line, separated by ';'
- variable substitution using "... ${name} ..." syntax
- special characters ('$', ';') can be escaped by prefixing with '\',
  for example:
	setenv bootcmd bootm \${address}
- You can also escape text by enclosing in single apostrophes, for example:
	setenv addip 'setenv bootargs $bootargs ip=$ipaddr:$serverip:$gatewayip:$netmask:$hostname::off'

Hush shell:
-----------

- similar to Bourne shell, with control structures like
  if...then...else...fi, for...do...done; while...do...done,
  until...do...done, ...
- supports environment ("global") variables (through setenv / saveenv
  commands) and local shell variables (through standard shell syntax
  "name=value"); only environment variables can be used with "run"
  command

General rules:
--------------

(1) If a command line (or an environment variable executed by a "run"
    command) contains several commands separated by semicolon, and
    one of these commands fails, then the remaining commands will be
    executed anyway.

(2) If you execute several variables with one call to run (i. e.
    calling run with a list af variables as arguments), any failing
    command will cause "run" to terminate, i. e. the remaining
    variables are not executed.

Note for Redundant Ethernet Interfaces:
=======================================

Some boards come with redundant ethernet interfaces; U-Boot supports
such configurations and is capable of automatic selection of a
"working" interface when needed. MAC assignment works as follows:

Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
"eth1addr" (=>eth1), "eth2addr", ...

If the network interface stores some valid MAC address (for instance
in SROM), this is used as default address if there is NO correspon-
ding setting in the environment; if the corresponding environment
variable is set, this overrides the settings in the card; that means:

o If the SROM has a valid MAC address, and there is no address in the
  environment, the SROM's address is used.

o If there is no valid address in the SROM, and a definition in the
  environment exists, then the value from the environment variable is
  used.

o If both the SROM and the environment contain a MAC address, and
  both addresses are the same, this MAC address is used.

o If both the SROM and the environment contain a MAC address, and the
  addresses differ, the value from the environment is used and a
  warning is printed.

o If neither SROM nor the environment contain a MAC address, an error
  is raised.


Image Formats:
==============

The "boot" commands of this monitor operate on "image" files which
can be basicly anything, preceeded by a special header; see the
definitions in include/image.h for details; basicly, the header
defines the following image properties:

* Target Operating System (Provisions for OpenBSD, NetBSD, FreeBSD,
  4.4BSD, Linux, SVR4, Esix, Solaris, Irix, SCO, Dell, NCR, VxWorks,
  LynxOS, pSOS, QNX, RTEMS, ARTOS;
  Currently supported: Linux, NetBSD, VxWorks, QNX, RTEMS, ARTOS, LynxOS).
* Target CPU Architecture (Provisions for Alpha, ARM, AVR32, Intel x86,
  IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
  Currently supported: ARM, AVR32, Intel x86, MIPS, NIOS, PowerPC).
* Compression Type (uncompressed, gzip, bzip2)
* Load Address
* Entry Point
* Image Name
* Image Timestamp

The header is marked by a special Magic Number, and both the header
and the data portions of the image are secured against corruption by
CRC32 checksums.


Linux Support:
==============

Although U-Boot should support any OS or standalone application
easily, the main focus has always been on Linux during the design of
U-Boot.

U-Boot includes many features that so far have been part of some
special "boot loader" code within the Linux kernel. Also, any
"initrd" images to be used are no longer part of one big Linux image;
instead, kernel and "initrd" are separate images. This implementation
serves several purposes:

- the same features can be used for other OS or standalone
  applications (for instance: using compressed images to reduce the
  Flash memory footprint)

- it becomes much easier to port new Linux kernel versions because
  lots of low-level, hardware dependent stuff are done by U-Boot

- the same Linux kernel image can now be used with different "initrd"
  images; of course this also means that different kernel images can
  be run with the same "initrd". This makes testing easier (you don't
  have to build a new "zImage.initrd" Linux image when you just
  change a file in your "initrd"). Also, a field-upgrade of the
  software is easier now.


Linux HOWTO:
============

Porting Linux to U-Boot based systems:
---------------------------------------

U-Boot cannot save you from doing all the necessary modifications to
configure the Linux device drivers for use with your target hardware
(no, we don't intend to provide a full virtual machine interface to
Linux :-).

But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).

Just make sure your machine specific header file (for instance
include/asm-ppc/tqm8xx.h) includes the same definition of the Board
Information structure as we define in include/u-boot.h, and make
sure that your definition of IMAP_ADDR uses the same value as your
U-Boot configuration in CFG_IMMR.


Configuring the Linux kernel:
-----------------------------

No specific requirements for U-Boot. Make sure you have some root
device (initial ramdisk, NFS) for your target system.


Building a Linux Image:
-----------------------

With U-Boot, "normal" build targets like "zImage" or "bzImage" are
not used. If you use recent kernel source, a new build target
"uImage" will exist which automatically builds an image usable by
U-Boot. Most older kernels also have support for a "pImage" target,
which was introduced for our predecessor project PPCBoot and uses a
100% compatible format.

Example:

	make TQM850L_config
	make oldconfig
	make dep
	make uImage

The "uImage" build target uses a special tool (in 'tools/mkimage') to
encapsulate a compressed Linux kernel image with header	 information,
CRC32 checksum etc. for use with U-Boot. This is what we are doing:

* build a standard "vmlinux" kernel image (in ELF binary format):

* convert the kernel into a raw binary image:

	${CROSS_COMPILE}-objcopy -O binary \
				 -R .note -R .comment \
				 -S vmlinux linux.bin

* compress the binary image:

	gzip -9 linux.bin

* package compressed binary image for U-Boot:

	mkimage -A ppc -O linux -T kernel -C gzip \
		-a 0 -e 0 -n "Linux Kernel Image" \
		-d linux.bin.gz uImage


The "mkimage" tool can also be used to create ramdisk images for use
with U-Boot, either separated from the Linux kernel image, or
combined into one file. "mkimage" encapsulates the images with a 64
byte header containing information about target architecture,
operating system, image type, compression method, entry points, time
stamp, CRC32 checksums, etc.

"mkimage" can be called in two ways: to verify existing images and
print the header information, or to build new images.

In the first form (with "-l" option) mkimage lists the information
contained in the header of an existing U-Boot image; this includes
checksum verification:

	tools/mkimage -l image
	  -l ==> list image header information

The second form (with "-d" option) is used to build a U-Boot image
from a "data file" which is used as image payload:

	tools/mkimage -A arch -O os -T type -C comp -a addr -e ep \
		      -n name -d data_file image
	  -A ==> set architecture to 'arch'
	  -O ==> set operating system to 'os'
	  -T ==> set image type to 'type'
	  -C ==> set compression type 'comp'
	  -a ==> set load address to 'addr' (hex)
	  -e ==> set entry point to 'ep' (hex)
	  -n ==> set image name to 'name'
	  -d ==> use image data from 'datafile'

Right now, all Linux kernels for PowerPC systems use the same load
address (0x00000000), but the entry point address depends on the
kernel version:

- 2.2.x kernels have the entry point at 0x0000000C,
- 2.3.x and later kernels have the entry point at 0x00000000.

So a typical call to build a U-Boot image would read:

	-> tools/mkimage -n '2.4.4 kernel for TQM850L' \
	> -A ppc -O linux -T kernel -C gzip -a 0 -e 0 \
	> -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz \
	> examples/uImage.TQM850L
	Image Name:   2.4.4 kernel for TQM850L
	Created:      Wed Jul 19 02:34:59 2000
	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
	Load Address: 0x00000000
	Entry Point:  0x00000000

To verify the contents of the image (or check for corruption):

	-> tools/mkimage -l examples/uImage.TQM850L
	Image Name:   2.4.4 kernel for TQM850L
	Created:      Wed Jul 19 02:34:59 2000
	Image Type:   PowerPC Linux Kernel Image (gzip compressed)
	Data Size:    335725 Bytes = 327.86 kB = 0.32 MB
	Load Address: 0x00000000