TQM850L_config TQM855L_config TQM860L_config
WALNUT405_config ZPC1900_config
- Note: for some board special configuration names may exist; check if
- additional information is available from the board vendor; for
- instance, the TQM8xxL systems run normally at 50 MHz and use a
- SCC for 10baseT ethernet; there are also systems with 80 MHz
- CPU clock, and an optional Fast Ethernet module is available
- for CPU's with FEC. You can select such additional "features"
- when chosing the configuration, i. e.
-
- make TQM860L_config
- - will configure for a plain TQM860L, i. e. 50MHz, no FEC
-
- make TQM860L_FEC_config
- - will configure for a TQM860L at 50MHz with FEC for ethernet
-
- make TQM860L_80MHz_config
- - will configure for a TQM860L at 80 MHz, with normal 10baseT
- interface
-
- make TQM860L_FEC_80MHz_config
- - will configure for a TQM860L at 80 MHz with FEC for ethernet
-
- make TQM823L_LCD_config
- - will configure for a TQM823L with U-Boot console on LCD
-
- make TQM823L_LCD_80MHz_config
- - will configure for a TQM823L at 80 MHz 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
-
-
- 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
-
- 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
- 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.
-
- 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.
+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
+
+
+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
+
+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
+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.
- ipaddr - IP address; needed for tftpboot command
+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.
- loadaddr - Default load address for commands like "bootp",
- "rarpboot", "tftpboot", "loadb" or "diskboot"
+Some configuration options can be set using Environment Variables:
- loads_echo - see CONFIG_LOADS_ECHO
+ baudrate - see CONFIG_BAUDRATE
- serverip - TFTP server IP address; needed for tftpboot command
+ bootdelay - see CONFIG_BOOTDELAY
- bootretry - see CONFIG_BOOT_RETRY_TIME
+ bootcmd - see CONFIG_BOOTCOMMAND
- bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
+ bootargs - Boot arguments when booting an RTOS image
- bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
+ bootfile - Name of the image to load with TFTP
- ethprime - When CONFIG_NET_MULTI is enabled controls which
- interface is used first.
+ 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
- ethact - When CONFIG_NET_MULTI is enabled controls which
- interface is currently active. For example you
- can do the following
+ autostart - if set to "yes", an image loaded using the "bootp",
+ "rarpboot", "tftpboot" or "diskboot" commands will
+ be automatically started (by internally calling
+ "bootm")
- => 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
+ 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.
- 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.
+ 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).
- vlan - When set to a value < 4095 the traffic over
- ethernet is encapsulated/received over 802.1q
- VLAN tagged frames.
+ 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
- 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:
+ setenv initrd_high 00c00000
- 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
+ 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
- There are two special Environment Variables:
+ loadaddr - Default load address for commands like "bootp",
+ "rarpboot", "tftpboot", "loadb" or "diskboot"
- serial# - contains hardware identification information such
- as type string and/or serial number
- ethaddr - Ethernet address
+ loads_echo - see CONFIG_LOADS_ECHO
- 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.
+ serverip - TFTP server IP address; needed for tftpboot command
+ bootretry - see CONFIG_BOOT_RETRY_TIME
- Further special Environment Variables:
+ bootdelaykey - see CONFIG_AUTOBOOT_DELAY_STR
- ver - Contains the U-Boot version string as printed
- with the "version" command. This variable is
- readonly (see CONFIG_VERSION_VARIABLE).
+ bootstopkey - see CONFIG_AUTOBOOT_STOP_STR
+ ethprime - When CONFIG_NET_MULTI is enabled controls which
+ interface is used first.
- Please note that changes to some configuration parameters may take
- only effect after the next boot (yes, that's just like Windoze :-).
-
+ ethact - When CONFIG_NET_MULTI is enabled controls which
+ interface is currently active. For example you
+ can do the following
- Command Line Parsing:
- =====================
+ => 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
- There are two different command line parsers available with U-Boot:
- the old "simple" one, and the much more powerful "hush" shell:
+ 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.
- Old, simple command line parser:
- --------------------------------
+ vlan - When set to a value < 4095 the traffic over
+ ethernet is encapsulated/received over 802.1q
+ VLAN tagged frames.
- - 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'
+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:
- Hush shell:
- -----------
+ 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
- - 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:
- --------------
+There are two special Environment Variables:
- (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.
+ serial# - contains hardware identification information such
+ as type string and/or serial number
+ ethaddr - Ethernet address
- (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.
+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.
- 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:
+Further special Environment Variables:
- Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
- MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
- "eth1addr" (=>eth1), "eth2addr", ...
+ ver - Contains the U-Boot version string as printed
+ with the "version" command. This variable is
+ readonly (see CONFIG_VERSION_VARIABLE).
- 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.
+Please note that changes to some configuration parameters may take
+only effect after the next boot (yes, that's just like Windoze :-).
- 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.
+Command Line Parsing:
+=====================
- 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.
+There are two different command line parsers available with U-Boot:
+the old "simple" one, and the much more powerful "hush" shell:
- o If neither SROM nor the environment contain a MAC address, an error
- is raised.
+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'
- Image Formats:
- ==============
+Hush shell:
+-----------
- 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:
+- 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:
+--------------
- * 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, Intel x86,
- IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
- Currently supported: ARM, Intel x86, MIPS, NIOS, PowerPC).
- * Compression Type (uncompressed, gzip, bzip2)
- * Load Address
- * Entry Point
- * Image Name
- * Image Timestamp
+(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.
- 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.
+(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:
+=======================================
- Linux Support:
- ==============
+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:
- 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.
+Network interfaces are numbered eth0, eth1, eth2, ... Corresponding
+MAC addresses can be stored in the environment as "ethaddr" (=>eth0),
+"eth1addr" (=>eth1), "eth2addr", ...
- 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:
+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:
- - the same features can be used for other OS or standalone
- applications (for instance: using compressed images to reduce the
- Flash memory footprint)
+o If the SROM has a valid MAC address, and there is no address in the
+ environment, the SROM's address is used.
- - it becomes much easier to port new Linux kernel versions because
- lots of low-level, hardware dependent stuff are done by U-Boot
+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.
- - 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.
+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.
- Linux HOWTO:
- ============
+o If neither SROM nor the environment contain a MAC address, an error
+ is raised.
- 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 :-).
+Image Formats:
+==============
- But now you can ignore ALL boot loader code (in arch/ppc/mbxboot).
+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:
- 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.
+* 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, Intel x86,
+ IA64, MIPS, NIOS, PowerPC, IBM S390, SuperH, Sparc, Sparc 64 Bit;
+ Currently supported: ARM, 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.
- Configuring the Linux kernel:
- -----------------------------
- No specific requirements for U-Boot. Make sure you have some root
- device (initial ramdisk, NFS) for your target system.
+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.
- Building a Linux Image:
- -----------------------
+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:
- 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.
+- the same features can be used for other OS or standalone
+ applications (for instance: using compressed images to reduce the
+ Flash memory footprint)
- Example:
+- it becomes much easier to port new Linux kernel versions because
+ lots of low-level, hardware dependent stuff are done by U-Boot
- make TQM850L_config
- make oldconfig
- make dep
- make uImage
+- 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.
- 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
+Linux HOWTO:
+============
- * package compressed binary image for U-Boot:
+Porting Linux to U-Boot based systems:
+---------------------------------------
- mkimage -A ppc -O linux -T kernel -C gzip \
- -a 0 -e 0 -n "Linux Kernel Image" \
- -d linux.bin.gz uImage
+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).
- 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.
+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.
- "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:
+Configuring the Linux kernel:
+-----------------------------
- tools/mkimage -l image
- -l ==> list image header information
+No specific requirements for U-Boot. Make sure you have some root
+device (initial ramdisk, NFS) for your target system.
+
+
+Building a Linux Image:
+-----------------------
- The second form (with "-d" option) is used to build a U-Boot image
- from a "data file" which is used as image payload:
+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
- 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 use the same load address (0x00000000),
- but the entry point address depends on the kernel version:
+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:
- - 2.2.x kernels have the entry point at 0x0000000C,
- - 2.3.x and later kernels have the entry point at 0x00000000.
+ 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 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
+ Entry Point: 0x00000000
+
+NOTE: for embedded systems where boot time is critical you can trade
+speed for memory and install an UNCOMPRESSED image instead: this
+needs more space in Flash, but boots much faster since it does not
+need to be uncompressed:
+
+ -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
+ -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
+ > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
+ > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
+ > examples/uImage.TQM850L-uncompressed
+ Image Name: 2.4.4 kernel for TQM850L
+ Created: Wed Jul 19 02:34:59 2000
+ Image Type: PowerPC Linux Kernel Image (uncompressed)
+ Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
+ Load Address: 0x00000000
+ Entry Point: 0x00000000
+
+
+Similar you can build U-Boot images from a 'ramdisk.image.gz' file
+when your kernel is intended to use an initial ramdisk:
+
+ -> tools/mkimage -n 'Simple Ramdisk Image' \
+ > -A ppc -O linux -T ramdisk -C gzip \
+ > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
+ Image Name: Simple Ramdisk Image
+ Created: Wed Jan 12 14:01:50 2000
+ Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
+ Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
+ Load Address: 0x00000000
+ Entry Point: 0x00000000
+
+
+Installing a Linux Image:
+-------------------------
+
+To downloading a U-Boot image over the serial (console) interface,
+you must convert the image to S-Record format:
+
+ objcopy -I binary -O srec examples/image examples/image.srec
+
+The 'objcopy' does not understand the information in the U-Boot
+image header, so the resulting S-Record file will be relative to
+address 0x00000000. To load it to a given address, you need to
+specify the target address as 'offset' parameter with the 'loads'
+command.
+
+Example: install the image to address 0x40100000 (which on the
+TQM8xxL is in the first Flash bank):
+
+ => erase 40100000 401FFFFF
+
+ .......... done
+ Erased 8 sectors
+
+ => loads 40100000
+ ## Ready for S-Record download ...
+ ~>examples/image.srec
+ 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
+ ...
+ 15989 15990 15991 15992
+ [file transfer complete]
+ [connected]
+ ## Start Addr = 0x00000000
+
+
+You can check the success of the download using the 'iminfo' command;
+this includes a checksum verification so you can be sure no data
+corruption happened:
+
+ => imi 40100000
+
+ ## Checking Image at 40100000 ...
+ Image Name: 2.2.13 for initrd on TQM850L
+ Image Type: PowerPC Linux Kernel Image (gzip compressed)
+ Data Size: 335725 Bytes = 327 kB = 0 MB
+ Load Address: 00000000
+ Entry Point: 0000000c
+ Verifying Checksum ... OK
+
+
+Boot Linux:
+-----------
+
+The "bootm" command is used to boot an application that is stored in
+memory (RAM or Flash). In case of a Linux kernel image, the contents
+of the "bootargs" environment variable is passed to the kernel as
+parameters. You can check and modify this variable using the
+"printenv" and "setenv" commands:
+
+
+ => printenv bootargs
+ bootargs=root=/dev/ram
+
+ => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
+
+ => printenv bootargs
+ bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
+
+ => bootm 40020000
+ ## Booting Linux kernel at 40020000 ...
+ Image Name: 2.2.13 for NFS on TQM850L
+ Image Type: PowerPC Linux Kernel Image (gzip compressed)
+ Data Size: 381681 Bytes = 372 kB = 0 MB
+ Load Address: 00000000
+ Entry Point: 0000000c
+ Verifying Checksum ... OK
+ Uncompressing Kernel Image ... OK
+ Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
+ Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
+ time_init: decrementer frequency = 187500000/60
+ Calibrating delay loop... 49.77 BogoMIPS
+ Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
+ ...
+
+If you want to boot a Linux kernel with initial ram disk, you pass
+the memory addresses of both the kernel and the initrd image (PPBCOOT
+format!) to the "bootm" command:
+
+ => imi 40100000 40200000
+
+ ## Checking Image at 40100000 ...
+ Image Name: 2.2.13 for initrd on TQM850L
+ Image Type: PowerPC Linux Kernel Image (gzip compressed)
+ Data Size: 335725 Bytes = 327 kB = 0 MB
+ Load Address: 00000000
+ Entry Point: 0000000c
+ Verifying Checksum ... OK
+
+ ## Checking Image at 40200000 ...
+ Image Name: Simple Ramdisk Image
+ Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
+ Data Size: 566530 Bytes = 553 kB = 0 MB
+ Load Address: 00000000
+ Entry Point: 00000000
+ Verifying Checksum ... OK
+
+ => bootm 40100000 40200000
+ ## Booting Linux kernel at 40100000 ...
+ Image Name: 2.2.13 for initrd on TQM850L
+ Image Type: PowerPC Linux Kernel Image (gzip compressed)
+ Data Size: 335725 Bytes = 327 kB = 0 MB
+ Load Address: 00000000
+ Entry Point: 0000000c
+ Verifying Checksum ... OK
+ Uncompressing Kernel Image ... OK
+ ## Loading RAMDisk Image at 40200000 ...
+ Image Name: Simple Ramdisk Image
+ Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
+ Data Size: 566530 Bytes = 553 kB = 0 MB
+ Load Address: 00000000
+ Entry Point: 00000000
+ Verifying Checksum ... OK
+ Loading Ramdisk ... OK
+ Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
+ Boot arguments: root=/dev/ram
+ time_init: decrementer frequency = 187500000/60
+ Calibrating delay loop... 49.77 BogoMIPS
+ ...
+ RAMDISK: Compressed image found at block 0
+ VFS: Mounted root (ext2 filesystem).
+
+ bash#
+
+More About U-Boot Image Types:
+------------------------------
+
+U-Boot supports the following image types:
+
+ "Standalone Programs" are directly runnable in the environment
+ provided by U-Boot; it is expected that (if they behave
+ well) you can continue to work in U-Boot after return from
+ the Standalone Program.
+ "OS Kernel Images" are usually images of some Embedded OS which
+ will take over control completely. Usually these programs
+ will install their own set of exception handlers, device
+ drivers, set up the MMU, etc. - this means, that you cannot
+ expect to re-enter U-Boot except by resetting the CPU.
+ "RAMDisk Images" are more or less just data blocks, and their
+ parameters (address, size) are passed to an OS kernel that is
+ being started.
+ "Multi-File Images" contain several images, typically an OS
+ (Linux) kernel image and one or more data images like
+ RAMDisks. This construct is useful for instance when you want
+ to boot over the network using BOOTP etc., where the boot
+ server provides just a single image file, but you want to get
+ for instance an OS kernel and a RAMDisk image.
+
+ "Multi-File Images" start with a list of image sizes, each
+ image size (in bytes) specified by an "uint32_t" in network
+ byte order. This list is terminated by an "(uint32_t)0".
+ Immediately after the terminating 0 follow the images, one by
+ one, all aligned on "uint32_t" boundaries (size rounded up to
+ a multiple of 4 bytes).
+
+ "Firmware Images" are binary images containing firmware (like
+ U-Boot or FPGA images) which usually will be programmed to
+ flash memory.
+
+ "Script files" are command sequences that will be executed by
+ U-Boot's command interpreter; this feature is especially
+ useful when you configure U-Boot to use a real shell (hush)
+ as command interpreter.
+
+
+Standalone HOWTO:
+=================
+
+One of the features of U-Boot is that you can dynamically load and
+run "standalone" applications, which can use some resources of
+U-Boot like console I/O functions or interrupt services.
+
+Two simple examples are included with the sources:
+
+"Hello World" Demo:
+-------------------
+
+'examples/hello_world.c' contains a small "Hello World" Demo
+application; it is automatically compiled when you build U-Boot.
+It's configured to run at address 0x00040004, so you can play with it
+like that:
+
+ => loads
+ ## Ready for S-Record download ...
+ ~>examples/hello_world.srec
+ 1 2 3 4 5 6 7 8 9 10 11 ...
+ [file transfer complete]
+ [connected]
+ ## Start Addr = 0x00040004
+
+ => go 40004 Hello World! This is a test.
+ ## Starting application at 0x00040004 ...
+ Hello World
+ argc = 7
+ argv[0] = "40004"
+ argv[1] = "Hello"
+ argv[2] = "World!"
+ argv[3] = "This"
+ argv[4] = "is"
+ argv[5] = "a"
+ argv[6] = "test."
+ argv[7] = "<NULL>"
+ Hit any key to exit ...
+
+ ## Application terminated, rc = 0x0
+
+Another example, which demonstrates how to register a CPM interrupt
+handler with the U-Boot code, can be found in 'examples/timer.c'.
+Here, a CPM timer is set up to generate an interrupt every second.
+The interrupt service routine is trivial, just printing a '.'
+character, but this is just a demo program. The application can be
+controlled by the following keys:
+
+ ? - print current values og the CPM Timer registers
+ b - enable interrupts and start timer
+ e - stop timer and disable interrupts
+ q - quit application
+
+ => loads
+ ## Ready for S-Record download ...
+ ~>examples/timer.srec
+ 1 2 3 4 5 6 7 8 9 10 11 ...
+ [file transfer complete]
+ [connected]
+ ## Start Addr = 0x00040004
+
+ => go 40004
+ ## Starting application at 0x00040004 ...
+ TIMERS=0xfff00980
+ Using timer 1
+ tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
+
+Hit 'b':
+ [q, b, e, ?] Set interval 1000000 us
+ Enabling timer
+Hit '?':
+ [q, b, e, ?] ........
+ tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
+Hit '?':
+ [q, b, e, ?] .
+ tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
+Hit '?':
+ [q, b, e, ?] .
+ tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
+Hit '?':
+ [q, b, e, ?] .
+ tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
+Hit 'e':
+ [q, b, e, ?] ...Stopping timer
+Hit 'q':
+ [q, b, e, ?] ## Application terminated, rc = 0x0
+
+
+Minicom warning:
+================
+
+Over time, many people have reported problems when trying to use the
+"minicom" terminal emulation program for serial download. I (wd)
+consider minicom to be broken, and recommend not to use it. Under
+Unix, I recommend to use C-Kermit for general purpose use (and
+especially for kermit binary protocol download ("loadb" command), and
+use "cu" for S-Record download ("loads" command).
+
+Nevertheless, if you absolutely want to use it try adding this
+configuration to your "File transfer protocols" section:
+
+ Name Program Name U/D FullScr IO-Red. Multi
+ X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
+ Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
+
+
+NetBSD Notes:
+=============
+
+Starting at version 0.9.2, U-Boot supports NetBSD both as host
+(build U-Boot) and target system (boots NetBSD/mpc8xx).
+
+Building requires a cross environment; it is known to work on
+NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
+need gmake since the Makefiles are not compatible with BSD make).
+Note that the cross-powerpc package does not install include files;
+attempting to build U-Boot will fail because <machine/ansi.h> is
+missing. This file has to be installed and patched manually:
+
+ # cd /usr/pkg/cross/powerpc-netbsd/include
+ # mkdir powerpc
+ # ln -s powerpc machine
+ # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
+ # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
+
+Native builds *don't* work due to incompatibilities between native
+and U-Boot include files.
+
+Booting assumes that (the first part of) the image booted is a
+stage-2 loader which in turn loads and then invokes the kernel
+proper. Loader sources will eventually appear in the NetBSD source
+tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
+meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
+details.
+
+
+Implementation Internals:
+=========================
+
+The following is not intended to be a complete description of every
+implementation detail. However, it should help to understand the
+inner workings of U-Boot and make it easier to port it to custom
+hardware.
+
+
+Initial Stack, Global Data:
+---------------------------
+
+The implementation of U-Boot is complicated by the fact that U-Boot
+starts running out of ROM (flash memory), usually without access to
+system RAM (because the memory controller is not initialized yet).
+This means that we don't have writable Data or BSS segments, and BSS
+is not initialized as zero. To be able to get a C environment working
+at all, we have to allocate at least a minimal stack. Implementation
+options for this are defined and restricted by the CPU used: Some CPU
+models provide on-chip memory (like the IMMR area on MPC8xx and
+MPC826x processors), on others (parts of) the data cache can be
+locked as (mis-) used as memory, etc.
+
+ Chris Hallinan posted a good summary of these issues to the
+ u-boot-users mailing list:
+
+ Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
+ From: "Chris Hallinan" <clh@net1plus.com>
+ Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
+ ...
+
+ Correct me if I'm wrong, folks, but the way I understand it
+ is this: Using DCACHE as initial RAM for Stack, etc, does not
+ require any physical RAM backing up the cache. The cleverness
+ is that the cache is being used as a temporary supply of
+ necessary storage before the SDRAM controller is setup. It's
+ beyond the scope of this list to expain the details, but you
+ can see how this works by studying the cache architecture and
+ operation in the architecture and processor-specific manuals.
+
+ OCM is On Chip Memory, which I believe the 405GP has 4K. It
+ is another option for the system designer to use as an
+ initial stack/ram area prior to SDRAM being available. Either
+ option should work for you. Using CS 4 should be fine if your
+ board designers haven't used it for something that would
+ cause you grief during the initial boot! It is frequently not
+ used.
+
+ CFG_INIT_RAM_ADDR should be somewhere that won't interfere
+ with your processor/board/system design. The default value
+ you will find in any recent u-boot distribution in
+ Walnut405.h should work for you. I'd set it to a value larger
+ than your SDRAM module. If you have a 64MB SDRAM module, set
+ it above 400_0000. Just make sure your board has no resources
+ that are supposed to respond to that address! That code in
+ start.S has been around a while and should work as is when
+ you get the config right.
+
+ -Chris Hallinan
+ DS4.COM, Inc.
+
+It is essential to remember this, since it has some impact on the C
+code for the initialization procedures:
+
+* Initialized global data (data segment) is read-only. Do not attempt
+ to write it.
+
+* Do not use any unitialized global data (or implicitely initialized
+ as zero data - BSS segment) at all - this is undefined, initiali-
+ zation is performed later (when relocating to RAM).
+
+* Stack space is very limited. Avoid big data buffers or things like
+ that.
+
+Having only the stack as writable memory limits means we cannot use
+normal global data to share information beween the code. But it
+turned out that the implementation of U-Boot can be greatly
+simplified by making a global data structure (gd_t) available to all
+functions. We could pass a pointer to this data as argument to _all_
+functions, but this would bloat the code. Instead we use a feature of
+the GCC compiler (Global Register Variables) to share the data: we
+place a pointer (gd) to the global data into a register which we
+reserve for this purpose.
+
+When choosing a register for such a purpose we are restricted by the
+relevant (E)ABI specifications for the current architecture, and by
+GCC's implementation.
+
+For PowerPC, the following registers have specific use:
+ R1: stack pointer
+ R2: TOC pointer
+ R3-R4: parameter passing and return values
+ R5-R10: parameter passing
+ R13: small data area pointer
+ R30: GOT pointer
+ R31: frame pointer
+
+ (U-Boot also uses R14 as internal GOT pointer.)
+
+ ==> U-Boot will use R29 to hold a pointer to the global data
+
+ Note: on PPC, we could use a static initializer (since the
+ address of the global data structure is known at compile time),
+ but it turned out that reserving a register results in somewhat
+ smaller code - although the code savings are not that big (on
+ average for all boards 752 bytes for the whole U-Boot image,
+ 624 text + 127 data).
+
+On ARM, the following registers are used:
+
+ R0: function argument word/integer result
+ R1-R3: function argument word
+ R9: GOT pointer
+ R10: stack limit (used only if stack checking if enabled)
+ R11: argument (frame) pointer
+ R12: temporary workspace
+ R13: stack pointer
+ R14: link register
+ R15: program counter
+
+ ==> U-Boot will use R8 to hold a pointer to the global data
+
+
+Memory Management:
+------------------
+
+U-Boot runs in system state and uses physical addresses, i.e. the
+MMU is not used either for address mapping nor for memory protection.
+
+The available memory is mapped to fixed addresses using the memory
+controller. In this process, a contiguous block is formed for each
+memory type (Flash, SDRAM, SRAM), even when it consists of several
+physical memory banks.
+
+U-Boot is installed in the first 128 kB of the first Flash bank (on
+TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
+booting and sizing and initializing DRAM, the code relocates itself
+to the upper end of DRAM. Immediately below the U-Boot code some
+memory is reserved for use by malloc() [see CFG_MALLOC_LEN
+configuration setting]. Below that, a structure with global Board
+Info data is placed, followed by the stack (growing downward).
+
+Additionally, some exception handler code is copied to the low 8 kB
+of DRAM (0x00000000 ... 0x00001FFF).
+
+So a typical memory configuration with 16 MB of DRAM could look like
+this:
+
+ 0x0000 0000 Exception Vector code
+ :
+ 0x0000 1FFF
+ 0x0000 2000 Free for Application Use
+ :
+ :
+
+ :
+ :
+ 0x00FB FF20 Monitor Stack (Growing downward)
+ 0x00FB FFAC Board Info Data and permanent copy of global data
+ 0x00FC 0000 Malloc Arena
+ :
+ 0x00FD FFFF
+ 0x00FE 0000 RAM Copy of Monitor Code
+ ... eventually: LCD or video framebuffer
+ ... eventually: pRAM (Protected RAM - unchanged by reset)
+ 0x00FF FFFF [End of RAM]
+
+
+System Initialization:
+----------------------
- So a typical call to build a U-Boot image would read:
+In the reset configuration, U-Boot starts at the reset entry point
+(on most PowerPC systens at address 0x00000100). Because of the reset
+configuration for CS0# this is a mirror of the onboard Flash memory.
+To be able to re-map memory U-Boot then jumps to its link address.
+To be able to implement the initialization code in C, a (small!)
+initial stack is set up in the internal Dual Ported RAM (in case CPUs
+which provide such a feature like MPC8xx or MPC8260), or in a locked
+part of the data cache. After that, U-Boot initializes the CPU core,
+the caches and the SIU.
+
+Next, all (potentially) available memory banks are mapped using a
+preliminary mapping. For example, we put them on 512 MB boundaries
+(multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
+on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
+programmed for SDRAM access. Using the temporary configuration, a
+simple memory test is run that determines the size of the SDRAM
+banks.
+
+When there is more than one SDRAM bank, and the banks are of
+different size, the largest is mapped first. For equal size, the first
+bank (CS2#) is mapped first. The first mapping is always for address
+0x00000000, with any additional banks following immediately to create
+contiguous memory starting from 0.
+
+Then, the monitor installs itself at the upper end of the SDRAM area
+and allocates memory for use by malloc() and for the global Board
+Info data; also, the exception vector code is copied to the low RAM
+pages, and the final stack is set up.
+
+Only after this relocation will you have a "normal" C environment;
+until that you are restricted in several ways, mostly because you are
+running from ROM, and because the code will have to be relocated to a
+new address in RAM.
+
+
+U-Boot Porting Guide:
+----------------------
- -> 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
+[Based on messages by Jerry Van Baren in the U-Boot-Users mailing
+list, October 2002]
- 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
- Entry Point: 0x00000000
+int main (int argc, char *argv[])
+{
+ sighandler_t no_more_time;
- NOTE: for embedded systems where boot time is critical you can trade
- speed for memory and install an UNCOMPRESSED image instead: this
- needs more space in Flash, but boots much faster since it does not
- need to be uncompressed:
-
- -> gunzip /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux.gz
- -> tools/mkimage -n '2.4.4 kernel for TQM850L' \
- > -A ppc -O linux -T kernel -C none -a 0 -e 0 \
- > -d /opt/elsk/ppc_8xx/usr/src/linux-2.4.4/arch/ppc/coffboot/vmlinux \
- > examples/uImage.TQM850L-uncompressed
- Image Name: 2.4.4 kernel for TQM850L
- Created: Wed Jul 19 02:34:59 2000
- Image Type: PowerPC Linux Kernel Image (uncompressed)
- Data Size: 792160 Bytes = 773.59 kB = 0.76 MB
- Load Address: 0x00000000
- Entry Point: 0x00000000
-
-
- Similar you can build U-Boot images from a 'ramdisk.image.gz' file
- when your kernel is intended to use an initial ramdisk:
-
- -> tools/mkimage -n 'Simple Ramdisk Image' \
- > -A ppc -O linux -T ramdisk -C gzip \
- > -d /LinuxPPC/images/SIMPLE-ramdisk.image.gz examples/simple-initrd
- Image Name: Simple Ramdisk Image
- Created: Wed Jan 12 14:01:50 2000
- Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
- Data Size: 566530 Bytes = 553.25 kB = 0.54 MB
- Load Address: 0x00000000
- Entry Point: 0x00000000
-
-
- Installing a Linux Image:
- -------------------------
-
- To downloading a U-Boot image over the serial (console) interface,
- you must convert the image to S-Record format:
-
- objcopy -I binary -O srec examples/image examples/image.srec
-
- The 'objcopy' does not understand the information in the U-Boot
- image header, so the resulting S-Record file will be relative to
- address 0x00000000. To load it to a given address, you need to
- specify the target address as 'offset' parameter with the 'loads'
- command.
-
- Example: install the image to address 0x40100000 (which on the
- TQM8xxL is in the first Flash bank):
-
- => erase 40100000 401FFFFF
-
- .......... done
- Erased 8 sectors
-
- => loads 40100000
- ## Ready for S-Record download ...
- ~>examples/image.srec
- 1 2 3 4 5 6 7 8 9 10 11 12 13 ...
- ...
- 15989 15990 15991 15992
- [file transfer complete]
- [connected]
- ## Start Addr = 0x00000000
-
-
- You can check the success of the download using the 'iminfo' command;
- this includes a checksum verification so you can be sure no data
- corruption happened:
-
- => imi 40100000
-
- ## Checking Image at 40100000 ...
- Image Name: 2.2.13 for initrd on TQM850L
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 335725 Bytes = 327 kB = 0 MB
- Load Address: 00000000
- Entry Point: 0000000c
- Verifying Checksum ... OK
-
-
- Boot Linux:
- -----------
-
- The "bootm" command is used to boot an application that is stored in
- memory (RAM or Flash). In case of a Linux kernel image, the contents
- of the "bootargs" environment variable is passed to the kernel as
- parameters. You can check and modify this variable using the
- "printenv" and "setenv" commands:
-
-
- => printenv bootargs
- bootargs=root=/dev/ram
-
- => setenv bootargs root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
-
- => printenv bootargs
- bootargs=root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
-
- => bootm 40020000
- ## Booting Linux kernel at 40020000 ...
- Image Name: 2.2.13 for NFS on TQM850L
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 381681 Bytes = 372 kB = 0 MB
- Load Address: 00000000
- Entry Point: 0000000c
- Verifying Checksum ... OK
- Uncompressing Kernel Image ... OK
- Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:35:17 MEST 2000
- Boot arguments: root=/dev/nfs rw nfsroot=10.0.0.2:/LinuxPPC nfsaddrs=10.0.0.99:10.0.0.2
- time_init: decrementer frequency = 187500000/60
- Calibrating delay loop... 49.77 BogoMIPS
- Memory: 15208k available (700k kernel code, 444k data, 32k init) [c0000000,c1000000]
- ...
-
- If you want to boot a Linux kernel with initial ram disk, you pass
- the memory addresses of both the kernel and the initrd image (PPBCOOT
- format!) to the "bootm" command:
-
- => imi 40100000 40200000
-
- ## Checking Image at 40100000 ...
- Image Name: 2.2.13 for initrd on TQM850L
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 335725 Bytes = 327 kB = 0 MB
- Load Address: 00000000
- Entry Point: 0000000c
- Verifying Checksum ... OK
-
- ## Checking Image at 40200000 ...
- Image Name: Simple Ramdisk Image
- Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
- Data Size: 566530 Bytes = 553 kB = 0 MB
- Load Address: 00000000
- Entry Point: 00000000
- Verifying Checksum ... OK
-
- => bootm 40100000 40200000
- ## Booting Linux kernel at 40100000 ...
- Image Name: 2.2.13 for initrd on TQM850L
- Image Type: PowerPC Linux Kernel Image (gzip compressed)
- Data Size: 335725 Bytes = 327 kB = 0 MB
- Load Address: 00000000
- Entry Point: 0000000c
- Verifying Checksum ... OK
- Uncompressing Kernel Image ... OK
- ## Loading RAMDisk Image at 40200000 ...
- Image Name: Simple Ramdisk Image
- Image Type: PowerPC Linux RAMDisk Image (gzip compressed)
- Data Size: 566530 Bytes = 553 kB = 0 MB
- Load Address: 00000000
- Entry Point: 00000000
- Verifying Checksum ... OK
- Loading Ramdisk ... OK
- Linux version 2.2.13 (wd@denx.local.net) (gcc version 2.95.2 19991024 (release)) #1 Wed Jul 19 02:32:08 MEST 2000
- Boot arguments: root=/dev/ram
- time_init: decrementer frequency = 187500000/60
- Calibrating delay loop... 49.77 BogoMIPS
- ...
- RAMDISK: Compressed image found at block 0
- VFS: Mounted root (ext2 filesystem).
-
- bash#
-
- More About U-Boot Image Types:
- ------------------------------
-
- U-Boot supports the following image types:
-
- "Standalone Programs" are directly runnable in the environment
- provided by U-Boot; it is expected that (if they behave
- well) you can continue to work in U-Boot after return from
- the Standalone Program.
- "OS Kernel Images" are usually images of some Embedded OS which
- will take over control completely. Usually these programs
- will install their own set of exception handlers, device
- drivers, set up the MMU, etc. - this means, that you cannot
- expect to re-enter U-Boot except by resetting the CPU.
- "RAMDisk Images" are more or less just data blocks, and their
- parameters (address, size) are passed to an OS kernel that is
- being started.
- "Multi-File Images" contain several images, typically an OS
- (Linux) kernel image and one or more data images like
- RAMDisks. This construct is useful for instance when you want
- to boot over the network using BOOTP etc., where the boot
- server provides just a single image file, but you want to get
- for instance an OS kernel and a RAMDisk image.
-
- "Multi-File Images" start with a list of image sizes, each
- image size (in bytes) specified by an "uint32_t" in network
- byte order. This list is terminated by an "(uint32_t)0".
- Immediately after the terminating 0 follow the images, one by
- one, all aligned on "uint32_t" boundaries (size rounded up to
- a multiple of 4 bytes).
-
- "Firmware Images" are binary images containing firmware (like
- U-Boot or FPGA images) which usually will be programmed to
- flash memory.
-
- "Script files" are command sequences that will be executed by
- U-Boot's command interpreter; this feature is especially
- useful when you configure U-Boot to use a real shell (hush)
- as command interpreter.
-
-
- Standalone HOWTO:
- =================
-
- One of the features of U-Boot is that you can dynamically load and
- run "standalone" applications, which can use some resources of
- U-Boot like console I/O functions or interrupt services.
-
- Two simple examples are included with the sources:
-
- "Hello World" Demo:
- -------------------
-
- 'examples/hello_world.c' contains a small "Hello World" Demo
- application; it is automatically compiled when you build U-Boot.
- It's configured to run at address 0x00040004, so you can play with it
- like that:
-
- => loads
- ## Ready for S-Record download ...
- ~>examples/hello_world.srec
- 1 2 3 4 5 6 7 8 9 10 11 ...
- [file transfer complete]
- [connected]
- ## Start Addr = 0x00040004
-
- => go 40004 Hello World! This is a test.
- ## Starting application at 0x00040004 ...
- Hello World
- argc = 7
- argv[0] = "40004"
- argv[1] = "Hello"
- argv[2] = "World!"
- argv[3] = "This"
- argv[4] = "is"
- argv[5] = "a"
- argv[6] = "test."
- argv[7] = "<NULL>"
- Hit any key to exit ...
-
- ## Application terminated, rc = 0x0
-
- Another example, which demonstrates how to register a CPM interrupt
- handler with the U-Boot code, can be found in 'examples/timer.c'.
- Here, a CPM timer is set up to generate an interrupt every second.
- The interrupt service routine is trivial, just printing a '.'
- character, but this is just a demo program. The application can be
- controlled by the following keys:
-
- ? - print current values og the CPM Timer registers
- b - enable interrupts and start timer
- e - stop timer and disable interrupts
- q - quit application
-
- => loads
- ## Ready for S-Record download ...
- ~>examples/timer.srec
- 1 2 3 4 5 6 7 8 9 10 11 ...
- [file transfer complete]
- [connected]
- ## Start Addr = 0x00040004
-
- => go 40004
- ## Starting application at 0x00040004 ...
- TIMERS=0xfff00980
- Using timer 1
- tgcr @ 0xfff00980, tmr @ 0xfff00990, trr @ 0xfff00994, tcr @ 0xfff00998, tcn @ 0xfff0099c, ter @ 0xfff009b0
-
- Hit 'b':
- [q, b, e, ?] Set interval 1000000 us
- Enabling timer
- Hit '?':
- [q, b, e, ?] ........
- tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0xef6, ter=0x0
- Hit '?':
- [q, b, e, ?] .
- tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x2ad4, ter=0x0
- Hit '?':
- [q, b, e, ?] .
- tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x1efc, ter=0x0
- Hit '?':
- [q, b, e, ?] .
- tgcr=0x1, tmr=0xff1c, trr=0x3d09, tcr=0x0, tcn=0x169d, ter=0x0
- Hit 'e':
- [q, b, e, ?] ...Stopping timer
- Hit 'q':
- [q, b, e, ?] ## Application terminated, rc = 0x0
-
-
- Minicom warning:
- ================
-
- Over time, many people have reported problems when trying to use the
- "minicom" terminal emulation program for serial download. I (wd)
- consider minicom to be broken, and recommend not to use it. Under
- Unix, I recommend to use C-Kermit for general purpose use (and
- especially for kermit binary protocol download ("loadb" command), and
- use "cu" for S-Record download ("loads" command).
-
- Nevertheless, if you absolutely want to use it try adding this
- configuration to your "File transfer protocols" section:
-
- Name Program Name U/D FullScr IO-Red. Multi
- X kermit /usr/bin/kermit -i -l %l -s Y U Y N N
- Y kermit /usr/bin/kermit -i -l %l -r N D Y N N
-
-
- NetBSD Notes:
- =============
-
- Starting at version 0.9.2, U-Boot supports NetBSD both as host
- (build U-Boot) and target system (boots NetBSD/mpc8xx).
-
- Building requires a cross environment; it is known to work on
- NetBSD/i386 with the cross-powerpc-netbsd-1.3 package (you will also
- need gmake since the Makefiles are not compatible with BSD make).
- Note that the cross-powerpc package does not install include files;
- attempting to build U-Boot will fail because <machine/ansi.h> is
- missing. This file has to be installed and patched manually:
-
- # cd /usr/pkg/cross/powerpc-netbsd/include
- # mkdir powerpc
- # ln -s powerpc machine
- # cp /usr/src/sys/arch/powerpc/include/ansi.h powerpc/ansi.h
- # ${EDIT} powerpc/ansi.h ## must remove __va_list, _BSD_VA_LIST
-
- Native builds *don't* work due to incompatibilities between native
- and U-Boot include files.
-
- Booting assumes that (the first part of) the image booted is a
- stage-2 loader which in turn loads and then invokes the kernel
- proper. Loader sources will eventually appear in the NetBSD source
- tree (probably in sys/arc/mpc8xx/stand/u-boot_stage2/); in the
- meantime, send mail to bruno@exet-ag.de and/or wd@denx.de for
- details.
-
-
- Implementation Internals:
- =========================
-
- The following is not intended to be a complete description of every
- implementation detail. However, it should help to understand the
- inner workings of U-Boot and make it easier to port it to custom
- hardware.
-
-
- Initial Stack, Global Data:
- ---------------------------
-
- The implementation of U-Boot is complicated by the fact that U-Boot
- starts running out of ROM (flash memory), usually without access to
- system RAM (because the memory controller is not initialized yet).
- This means that we don't have writable Data or BSS segments, and BSS
- is not initialized as zero. To be able to get a C environment working
- at all, we have to allocate at least a minimal stack. Implementation
- options for this are defined and restricted by the CPU used: Some CPU
- models provide on-chip memory (like the IMMR area on MPC8xx and
- MPC826x processors), on others (parts of) the data cache can be
- locked as (mis-) used as memory, etc.
-
- Chris Hallinan posted a good summary of these issues to the
- u-boot-users mailing list:
-
- Subject: RE: [U-Boot-Users] RE: More On Memory Bank x (nothingness)?
- From: "Chris Hallinan" <clh@net1plus.com>
- Date: Mon, 10 Feb 2003 16:43:46 -0500 (22:43 MET)
- ...
-
- Correct me if I'm wrong, folks, but the way I understand it
- is this: Using DCACHE as initial RAM for Stack, etc, does not
- require any physical RAM backing up the cache. The cleverness
- is that the cache is being used as a temporary supply of
- necessary storage before the SDRAM controller is setup. It's
- beyond the scope of this list to expain the details, but you
- can see how this works by studying the cache architecture and
- operation in the architecture and processor-specific manuals.
-
- OCM is On Chip Memory, which I believe the 405GP has 4K. It
- is another option for the system designer to use as an
- initial stack/ram area prior to SDRAM being available. Either
- option should work for you. Using CS 4 should be fine if your
- board designers haven't used it for something that would
- cause you grief during the initial boot! It is frequently not
- used.
-
- CFG_INIT_RAM_ADDR should be somewhere that won't interfere
- with your processor/board/system design. The default value
- you will find in any recent u-boot distribution in
- Walnut405.h should work for you. I'd set it to a value larger
- than your SDRAM module. If you have a 64MB SDRAM module, set
- it above 400_0000. Just make sure your board has no resources
- that are supposed to respond to that address! That code in
- start.S has been around a while and should work as is when
- you get the config right.
-
- -Chris Hallinan
- DS4.COM, Inc.
-
- It is essential to remember this, since it has some impact on the C
- code for the initialization procedures:
-
- * Initialized global data (data segment) is read-only. Do not attempt
- to write it.
-
- * Do not use any unitialized global data (or implicitely initialized
- as zero data - BSS segment) at all - this is undefined, initiali-
- zation is performed later (when relocating to RAM).
-
- * Stack space is very limited. Avoid big data buffers or things like
- that.
-
- Having only the stack as writable memory limits means we cannot use
- normal global data to share information beween the code. But it
- turned out that the implementation of U-Boot can be greatly
- simplified by making a global data structure (gd_t) available to all
- functions. We could pass a pointer to this data as argument to _all_
- functions, but this would bloat the code. Instead we use a feature of
- the GCC compiler (Global Register Variables) to share the data: we
- place a pointer (gd) to the global data into a register which we
- reserve for this purpose.
-
- When choosing a register for such a purpose we are restricted by the
- relevant (E)ABI specifications for the current architecture, and by
- GCC's implementation.
-
- For PowerPC, the following registers have specific use:
- R1: stack pointer
- R2: TOC pointer
- R3-R4: parameter passing and return values
- R5-R10: parameter passing
- R13: small data area pointer
- R30: GOT pointer
- R31: frame pointer
-
- (U-Boot also uses R14 as internal GOT pointer.)
-
- ==> U-Boot will use R29 to hold a pointer to the global data
-
- Note: on PPC, we could use a static initializer (since the
- address of the global data structure is known at compile time),
- but it turned out that reserving a register results in somewhat
- smaller code - although the code savings are not that big (on
- average for all boards 752 bytes for the whole U-Boot image,
- 624 text + 127 data).
-
- On ARM, the following registers are used:
-
- R0: function argument word/integer result
- R1-R3: function argument word
- R9: GOT pointer
- R10: stack limit (used only if stack checking if enabled)
- R11: argument (frame) pointer
- R12: temporary workspace
- R13: stack pointer
- R14: link register
- R15: program counter
-
- ==> U-Boot will use R8 to hold a pointer to the global data
-
-
- Memory Management:
- ------------------
-
- U-Boot runs in system state and uses physical addresses, i.e. the
- MMU is not used either for address mapping nor for memory protection.
-
- The available memory is mapped to fixed addresses using the memory
- controller. In this process, a contiguous block is formed for each
- memory type (Flash, SDRAM, SRAM), even when it consists of several
- physical memory banks.
-
- U-Boot is installed in the first 128 kB of the first Flash bank (on
- TQM8xxL modules this is the range 0x40000000 ... 0x4001FFFF). After
- booting and sizing and initializing DRAM, the code relocates itself
- to the upper end of DRAM. Immediately below the U-Boot code some
- memory is reserved for use by malloc() [see CFG_MALLOC_LEN
- configuration setting]. Below that, a structure with global Board
- Info data is placed, followed by the stack (growing downward).
-
- Additionally, some exception handler code is copied to the low 8 kB
- of DRAM (0x00000000 ... 0x00001FFF).
-
- So a typical memory configuration with 16 MB of DRAM could look like
- this:
-
- 0x0000 0000 Exception Vector code
- :
- 0x0000 1FFF
- 0x0000 2000 Free for Application Use
- :
- :
-
- :
- :
- 0x00FB FF20 Monitor Stack (Growing downward)
- 0x00FB FFAC Board Info Data and permanent copy of global data
- 0x00FC 0000 Malloc Arena
- :
- 0x00FD FFFF
- 0x00FE 0000 RAM Copy of Monitor Code
- ... eventually: LCD or video framebuffer
- ... eventually: pRAM (Protected RAM - unchanged by reset)
- 0x00FF FFFF [End of RAM]
-
-
- System Initialization:
- ----------------------
-
- In the reset configuration, U-Boot starts at the reset entry point
- (on most PowerPC systens at address 0x00000100). Because of the reset
- configuration for CS0# this is a mirror of the onboard Flash memory.
- To be able to re-map memory U-Boot then jumps to its link address.
- To be able to implement the initialization code in C, a (small!)
- initial stack is set up in the internal Dual Ported RAM (in case CPUs
- which provide such a feature like MPC8xx or MPC8260), or in a locked
- part of the data cache. After that, U-Boot initializes the CPU core,
- the caches and the SIU.
-
- Next, all (potentially) available memory banks are mapped using a
- preliminary mapping. For example, we put them on 512 MB boundaries
- (multiples of 0x20000000: SDRAM on 0x00000000 and 0x20000000, Flash
- on 0x40000000 and 0x60000000, SRAM on 0x80000000). Then UPM A is
- programmed for SDRAM access. Using the temporary configuration, a
- simple memory test is run that determines the size of the SDRAM
- banks.
-
- When there is more than one SDRAM bank, and the banks are of
- different size, the largest is mapped first. For equal size, the first
- bank (CS2#) is mapped first. The first mapping is always for address
- 0x00000000, with any additional banks following immediately to create
- contiguous memory starting from 0.
-
- Then, the monitor installs itself at the upper end of the SDRAM area
- and allocates memory for use by malloc() and for the global Board
- Info data; also, the exception vector code is copied to the low RAM
- pages, and the final stack is set up.
-
- Only after this relocation will you have a "normal" C environment;
- until that you are restricted in several ways, mostly because you are
- running from ROM, and because the code will have to be relocated to a
- new address in RAM.
-
-
- U-Boot Porting Guide:
- ----------------------
-
- [Based on messages by Jerry Van Baren in the U-Boot-Users mailing
- list, October 2002]
-
-
- int main (int argc, char *argv[])
- {
- sighandler_t no_more_time;
-
- signal (SIGALRM, no_more_time);
- alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
-
- if (available_money > available_manpower) {
- pay consultant to port U-Boot;
- return 0;
- }
-
- Download latest U-Boot source;
-
- Subscribe to u-boot-users mailing list;
-
- if (clueless) {
- email ("Hi, I am new to U-Boot, how do I get started?");
- }
-
- while (learning) {
- Read the README file in the top level directory;
- Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
- Read the source, Luke;
- }
-
- if (available_money > toLocalCurrency ($2500)) {
- Buy a BDI2000;
- } else {
- Add a lot of aggravation and time;
- }
-
- Create your own board support subdirectory;
-
- Create your own board config file;
-
- while (!running) {
- do {
- Add / modify source code;
- } until (compiles);
- Debug;
- if (clueless)
- email ("Hi, I am having problems...");
- }
- Send patch file to Wolfgang;
+ signal (SIGALRM, no_more_time);
+ alarm (PROJECT_DEADLINE - toSec (3 * WEEK));
+ if (available_money > available_manpower) {
+ pay consultant to port U-Boot;
return 0;
}
- void no_more_time (int sig)
- {
- hire_a_guru();
+ Download latest U-Boot source;
+
+ Subscribe to u-boot-users mailing list;
+
+ if (clueless) {
+ email ("Hi, I am new to U-Boot, how do I get started?");
+ }
+
+ while (learning) {
+ Read the README file in the top level directory;
+ Read http://www.denx.de/twiki/bin/view/DULG/Manual ;
+ Read the source, Luke;
+ }
+
+ if (available_money > toLocalCurrency ($2500)) {
+ Buy a BDI2000;
+ } else {
+ Add a lot of aggravation and time;
}
+ Create your own board support subdirectory;
+
+ Create your own board config file;
+
+ while (!running) {
+ do {
+ Add / modify source code;
+ } until (compiles);
+ Debug;
+ if (clueless)
+ email ("Hi, I am having problems...");
+ }
+ Send patch file to Wolfgang;
+
+ return 0;
+}
+
+void no_more_time (int sig)
+{
+ hire_a_guru();
+}
+
- Coding Standards:
- -----------------
+Coding Standards:
+-----------------
- All contributions to U-Boot should conform to the Linux kernel
- coding style; see the file "Documentation/CodingStyle" in your Linux
- kernel source directory.
+All contributions to U-Boot should conform to the Linux kernel
+coding style; see the file "Documentation/CodingStyle" in your Linux
+kernel source directory.
- Please note that U-Boot is implemented in C (and to some small parts
- in Assembler); no C++ is used, so please do not use C++ style
- comments (//) in your code.
+Please note that U-Boot is implemented in C (and to some small parts
+in Assembler); no C++ is used, so please do not use C++ style
+comments (//) in your code.
- Please also stick to the following formatting rules:
- - remove any trailing white space
- - use TAB characters for indentation, not spaces
- - make sure NOT to use DOS '\r\n' line feeds
- - do not add more than 2 empty lines to source files
- - do not add trailing empty lines to source files
+Please also stick to the following formatting rules:
+- remove any trailing white space
+- use TAB characters for indentation, not spaces
+- make sure NOT to use DOS '\r\n' line feeds
+- do not add more than 2 empty lines to source files
+- do not add trailing empty lines to source files
- Submissions which do not conform to the standards may be returned
- with a request to reformat the changes.
+Submissions which do not conform to the standards may be returned
+with a request to reformat the changes.
- Submitting Patches:
- -------------------
+Submitting Patches:
+-------------------
- Since the number of patches for U-Boot is growing, we need to
- establish some rules. Submissions which do not conform to these rules
- may be rejected, even when they contain important and valuable stuff.
+Since the number of patches for U-Boot is growing, we need to
+establish some rules. Submissions which do not conform to these rules
+may be rejected, even when they contain important and valuable stuff.
- When you send a patch, please include the following information with
- it:
+When you send a patch, please include the following information with
+it:
- * For bug fixes: a description of the bug and how your patch fixes
- this bug. Please try to include a way of demonstrating that the
- patch actually fixes something.
+* For bug fixes: a description of the bug and how your patch fixes
+ this bug. Please try to include a way of demonstrating that the
+ patch actually fixes something.
- * For new features: a description of the feature and your
- implementation.
+* For new features: a description of the feature and your
+ implementation.
- * A CHANGELOG entry as plaintext (separate from the patch)
+* A CHANGELOG entry as plaintext (separate from the patch)
- * For major contributions, your entry to the CREDITS file
+* For major contributions, your entry to the CREDITS file
- * When you add support for a new board, don't forget to add this
- board to the MAKEALL script, too.
+* When you add support for a new board, don't forget to add this
+ board to the MAKEALL script, too.
- * If your patch adds new configuration options, don't forget to
- document these in the README file.
+* If your patch adds new configuration options, don't forget to
+ document these in the README file.
- * The patch itself. If you are accessing the CVS repository use "cvs
- update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
- version of diff does not support these options, then get the latest
- version of GNU diff.
+* The patch itself. If you are accessing the CVS repository use "cvs
+ update; cvs diff -puRN"; else, use "diff -purN OLD NEW". If your
+ version of diff does not support these options, then get the latest
+ version of GNU diff.
- The current directory when running this command shall be the top
- level directory of the U-Boot source tree, or it's parent directory
- (i. e. please make sure that your patch includes sufficient
- directory information for the affected files).
+ The current directory when running this command shall be the top
+ level directory of the U-Boot source tree, or it's parent directory
+ (i. e. please make sure that your patch includes sufficient
+ directory information for the affected files).
- We accept patches as plain text, MIME attachments or as uuencoded
- gzipped text.
+ We accept patches as plain text, MIME attachments or as uuencoded
+ gzipped text.
- * If one logical set of modifications affects or creates several
- files, all these changes shall be submitted in a SINGLE patch file.
+* If one logical set of modifications affects or creates several
+ files, all these changes shall be submitted in a SINGLE patch file.
- * Changesets that contain different, unrelated modifications shall be
- submitted as SEPARATE patches, one patch per changeset.
+* Changesets that contain different, unrelated modifications shall be
+ submitted as SEPARATE patches, one patch per changeset.
- Notes:
+Notes:
- * Before sending the patch, run the MAKEALL script on your patched
- source tree and make sure that no errors or warnings are reported
- for any of the boards.
+* Before sending the patch, run the MAKEALL script on your patched
+ source tree and make sure that no errors or warnings are reported
+ for any of the boards.
- * Keep your modifications to the necessary minimum: A patch
- containing several unrelated changes or arbitrary reformats will be
- returned with a request to re-formatting / split it.
+* Keep your modifications to the necessary minimum: A patch
+ containing several unrelated changes or arbitrary reformats will be
+ returned with a request to re-formatting / split it.
- * If you modify existing code, make sure that your new code does not
- add to the memory footprint of the code ;-) Small is beautiful!
- When adding new features, these should compile conditionally only
- (using #ifdef), and the resulting code with the new feature
- disabled must not need more memory than the old code without your
- modification.
+* If you modify existing code, make sure that your new code does not
+ add to the memory footprint of the code ;-) Small is beautiful!
+ When adding new features, these should compile conditionally only
+ (using #ifdef), and the resulting code with the new feature
+ disabled must not need more memory than the old code without your
+ modification.
projects / u-boot / commitdiff