doc: rework user manual

Signed-off-by: Robert Schwebel <r.schwebel@pengutronix.de>

1 files changed, 70 insertions, 162 deletions

diff --git a/Documentation/barebox-main.dox b/Documentation/barebox-main.dox
index fb780e6364..90fce8ec8a 100644
--- a/Documentation/barebox-main.dox
+++ b/Documentation/barebox-main.dox
@@ -1,166 +1,74 @@
-/** @mainpage Universal Bootloader
-
-@section barebox_intro Introduction
-
-@a Barebox is a bootloader which follows the tradition of U-Boot.  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.
-
-@par General features include:
-
-- A posix based file API
-  - inside @a barebox the usual open/close/read/write/lseek functions are used.
-    This makes it familiar to everyone who has programmed under unix systems.
-
-- usual shell commands like ls/cd/mkdir/echo/cat,...
-
-- The environment is not a variable store anymore, but a file store. It has
-  currently some limitations, of course. The environment is not a real
-  read/write filesystem, it is more like a tar archive, or even more like
-  an ar archive, because it cannot handle directories. The saveenv command
-  saves the files under a certain directory (by default /env) in persistent
-  storage (by default /dev/env0). There is a counterpart called loadenv, too.
+/** @mainpage Barebox
+
+Barebox is a bootloader that initializes a hardware and boots Linux and
+maybe other operating systems or bare metal code on a variety of
+processors. It was initialy derived from U-Boot and captures up with
+several of it's ideas, so users being familiar with U-Boot should come
+into production quickly with Barebox.
+
+However, as the Barebox developers are highly addicted to the Linux
+kernel, it's coding style and code quality, we try to stick as closely
+as possible to the methodologies and techniques developed in Linux. In
+addition we have a strong background in POSIX, so you'll find several
+good old Unix traditions realized in Barebox as well.
+
+@par Highlights:
+
+- <b>POSIX File API:</b><br>
+  @a Barebox uses the the well known open/close/read/write/lseek access
+  functions, together with a model of representing devices by files. This
+  makes the APIs familiar to everyone who has experience with Unix
+  systems.
+
+- <b>Shell:</b><br>
+  We have the standard shell commands like ls/cd/mkdir/echo/cat,...
+
+- <b>Environment Filesystem:</b><br>
+  In contrast to U-Boot, Barebox doesn't misuse the environment for
+  scripting. If you start the bootloader, it gives you a shell and
+  something that looks like a filesystem. In fact it isn't: it is a very
+  simple ar archive being extracted from flash into a ramdisk with 'loadenv'
+  and stored back with 'saveenv'.
+
+- <b>Filesystem Support:</b><br>
+  When starting up, the environment is mounted to /, followed by a
+  device filesytem being mounted to /dev in order to make it possible to
+  access devices. Other filesystems can be mounted on demand.
+
+- <b>Driver Model (borrowed from Linux):</b><br>
+  Barebox follows the Linux driver model: devices can be specified in a
+  hardware specific file, and drivers feel responsible for these devices
+  if they have the same name.
+
+- <b>Clocksource:</b><br>
+  We use the clocksource API knwon from Linux.
+
+- <b>Kconfig/Kbuild:</b><br>
+  This gives us parallel builds and removes the need for lots of ifdefs.
+
+- <b>Sandbox:</b><br>
+  If you develop features for @a Barebox, you can use the 'sandbox'
+  target which compiles @a Barebox as a POSIX application in the Linux
+  userspace: it can be started like a normal command and even has
+  network access (tun/tap). Files from the local filesytem can be used
+  to simulate devices.
+
+- <b>Device Parameters:</b><br>
+  There is a parameter model in @a Barebox: each device can specify it's
+  own parameters, which do exist for every instance. Parameters can be
+  changed on the command line with \<devid\>.\<param\>="...". For
+  example, if you want to access the IPv4 address for eth0, this is done
+  with 'eth0.ip=192.168.0.7' and 'echo $eth0.ip'.
+
+- <b>Getopt:</b><br>
+  @a Barebox has a lightweight getopt() implementation. This makes it
+  unnecessary to use positional parameters, which can be hard to read.
+
+- <b>Integrated Editor:</b><br>
+  Scripts can be edited with a small integrated fullscreen editor.
+  This editor has no features except the ones really needed: moving
+  the cursor around, typing characters, exiting and saving.
 
-- Real filesystem support
-  - The loader starts up with mounting a ramdisk on /. Then a devfs is mounted
-    on /dev allowing the user (or shell commands) to access devices. Apart from
-    these two filesystems there is currently one filesystem ported: cramfs. One
-    can mount it with the usual mount command.
-
-- device/driver model
-  - Devices are no longer described by defines in the config file. Instead
-    there are devices which can be registered in the board .c file or
-    dynamically allocated. Drivers will match upon the devices automatically.
-
-- clocksource support
-  - Timekeeping has been simplified by the use of the Linux clocksource API.
-    Only one function is needed for a new board, no [gs]et_timer[masked]() or
-    reset_timer[masked]() functions.
-
-- Kconfig and Kernel build system
-  - Only targets which are really needed get recompiled. Parallel builds are
-    no problem anymore. This also removes the need for many many ifdefs in
-    the code.
-
-- simulation target
-  - @a barebox can be compiled to run under Linux. While this is rather useless
-    in real world this is a great debugging and development aid. New features
-    can be easily developed and tested on long train journeys and started
-    under gdb. There is a console driver for linux which emulates a serial
-    device and a tap based ethernet driver. Linux files can be mapped to
-    devices under @a barebox to emulate storage devices.
-
-- device parameter support
-  - Each device can have a unlimited number of parameters. They can be accessed
-    on the command line with \<devid\>.\<param\>="...", for example
-    'eth0.ip=192.168.0.7' or 'echo $eth0.ip'
-
-- initcalls
-  - hooks in the startup process can be achieved with *_initcall() directives
-    in each file.
-
-- getopt
-  - There is a small getopt implementation. Some commands got really
-    complicated (both in code and in usage) due to the fact that @a U-Boot only
-    allowed positional parameters.
-
-- editor
-  - Scripts can be edited with a small editor. This editor has no features
-    except the ones really needed: moving the cursor and typing characters.
-
-@par Building barebox
-
-@a Barebox uses the Linux kernel's build system. It consists of two parts:
-the makefile infrastructure (kbuild), plus a configuration system
-(kconfig). So building @a barebox is very similar to building the Linux
-kernel.
-
-For the examples below, we use the User Mode @a barebox implementation, which
-is a port of @a barebox to the Linux userspace. This makes it possible to
-test drive the code without having real hardware. So for this test
-scenario, @p ARCH=sandbox is the valid architecture selection. This currently
-only works on ia32 hosts and partly on x86-64.
-
-Selection of the architecture and the cross compiler can be done in two
-ways. You can either specify it using the environment variables @p ARCH
-and @p CROSS_COMPILE, or you can create the soft links cross_arch and
-cross_compile pointing to your architecture and compiler. For @p ARCH=sandbox
-we do not need a cross compiler so it is sufficient to specify the
-architecture:
-
-@code # ln -s arch/sandbox cross_arch @endcode
-
-In order to configure the various aspects of @a barebox, start the @a barebox
-configuration system:
-
-@code # make menuconfig @endcode
-
-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 sandbox_defconfig'), there is a .config file in the toplevel
-directory of the sourcecode.
-
-Once @a barebox is configured, we can start the compilation
-
-@code # make @endcode
-
-If everything goes well, the result is a file called @p barebox:
-
-@code
-  # ls -l barebox
-    -rwxr-xr-x 1 rsc ptx 114073 Jun 26 22:34 barebox
-@endcode
-
-@a barebox usually needs an environment for storing the configuration data.
-You can generate an environment using the example environment contained
-in arch/sanbox/board/env:
-
-@code # ./scripts/bareboxenv -s -p 0x10000 arch/sanbox/board/env/ env.bin @endcode
-
-To get some files to play with you can generate a cramfs image:
-
-@code # mkcramfs somedir/ cramfs.bin @endcode
-
-The @a barebox image is a normal Linux executable, so it can be started
-just like every other program:
-
-@code
-  # ./barebox -e env.bin -i cramfs.bin
-
-  barebox 2.0.0-trunk (Jun 26 2007 - 22:34:38)
-
-  loading environment from /dev/env0
-  barebox\> /
-@endcode
-
-Specifying -[ie] \<file\> tells @a barebox to map the file as a device
-under @p /dev. Files given with '-e' will appear as @p /dev/env[n]. Files
-given with '-i' will appear as @p /dev/fd[n].
-If @a barebox finds a valid configuration sector on @p /dev/env0 it will
-load it to @p /env. It then executes @p /env/init if it exists. If you have
-loaded the example environment @a barebox will show you a menu asking for
-your settings.
-
-If you have started @a barebox as root you will find a new tap device on your
-host which you can configure using ifconfig. Once you configured the
-network settings accordingly you can do a ping or tftpboot.
-
-If you have mapped a cramfs image try mounting it with
-
-@code
-  # mkdir /cram
-  # mount /dev/fd0 cramfs /cram
-@endcode
-
-Memory can be examined as usual using @p md/mw commands. They both understand
-the -f \<file\> option to tell the commands that they should work on the
-specified files instead of @p /dev/mem which holds the complete address space.
-Note that if you call 'md /dev/fd0' (without -f) @a barebox will segfault on
-the host, because it will interpret @p /dev/fd0 as a number.
 
 @par Directory layout