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README.u2

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+U2Boot
+------
+
+This is u2boot, our proposal for a next generation of the famous U-Boot
+bootloader. U-Boot offers an excellent choice as a bootloader for
+today's embedded systems, seen from a user's point of view.
+Nevertheless, there are quite some design flaws which turned out over
+the last years and we think that they cannot be solved in a production
+tree. So this tree tries to do several things right - without caring
+about losing support for old boards. So if you aim at stability at this
+time, stay with the official U-Boot releases.
+
+
+Building U-Boot
+---------------
+
+U-Boot uses the Linux kernel's build system. It consists of two parts:
+the makefile infrastructure (kbuild), plus a configuration system
+(kconfig). So building U-Boot is very similar to building the Linux
+kernel.
+
+For the examples below, we use the User Mode U-Boot implementatio, which
+is a port of U-Boot to the Linux userspace. This makes it possible to
+test drive the code without having real hardware. So for this test
+scenario, ARCH=linux is the valid architecture selection.
+
+First, select your architecture in a persistent way by creating a soft
+link:
+
+  # ln -s linux cross_arch
+
+In order to configure the various aspects of U-Boot, start the U-Boot
+configuration system:
+
+  # make menuconfig
+
+This command starts a menu box and lets you select all the different
+options available for your architecture. Once the configuration was
+finished (you can simulate this by using the standard demo config file
+with 'make linux_defconfig'), there is a .config file in the toplevel
+directory of the sourcode.
+
+U-Boot usually needs an environment, storing the configuation data, plus
+a filesystem space for scripts etc. You can create one locally with
+
+  # dd if=/dev/zero of=env.bin bs=1024 count=128
+  # FIXME - what to do to get a solid environemt
+  # dd if=/dev/zero of=cramfs.bin bs=1024 count=128
+  # FIXME - create filesystem
+
+Once U-Boot is configured, we can start the compilation
+
+  # make
+
+If everything goes well, the result is a file called uboot:
+
+  # ls -l uboot
+    -rwxr-xr-x 1 rsc ptx 114073 Jun 26 22:34 uboot
+
+This U-Boot image is a normal Linux executable, so it can be started
+just like evary other program:
+
+  # ./uboot -e env.bin -i cramfs.bin
+
+  U-Boot 2.0.0-trunk (Jun 26 2007 - 22:34:38)
+
+  loading environment from /dev/env0
+  uboot> /
+
+FIXME: cfi currently doesn't work with um-uboot
+
+
+Commands
+--------
+
+devinfo
+addpart
+pwd
+cd
+ls
+cat
+tftpboot <dest> <source> FIXME: order?
+tftpboot /dev/nor0.1 <source>
+erase -f /dev/nor0.1
+help
+edit -> ctrl-c ctrl-d
+md -f /dev/nor0.1
+exec /env/init FIXME: doesn't work yet
+saveenv (makes /env persistent) -> /dev/env0
+printenv (FIXME: obsolete)
+mount
+
+Shell
+-----
+
+- doesn't have switch/case yet
+- only one variable space
+[ ] add variable space
+
+Drivers
+-------
+
+/dev
+serial
+partition
+environment -> /env; /env/init
+
+Design
+------
+
+include/driver.h
+board/scb9328.c
+include/param.h: each device can have parameters; can be changed on
+runtime; get/set can be overwritten by implementation.
+
+- xfunctions: do panic if error
+- proposed design:
+  arch/
+  arch/arm/cpu-arm920t/
+  arch/arm/board-.../
+  board/ is obsolete
+
+- arch/*/Makefile is central makefile
+
+