README: rewrite some u-boot leftovers
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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README
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README
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barebox
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Barebox
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------
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-------
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This is barebox, our proposal for a next generation of the famous barebox
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Barebox is a bootloader that follows the tradition of Das U-Boot, while
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bootloader. barebox offers an excellent choice as a bootloader for
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adapting modern design ideas from the Linux kernel.
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today's embedded systems, seen from a user's point of view.
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Nevertheless, there are quite some design flaws which turned out over
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the last years and we think that they cannot be solved in a production
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tree. So this tree tries to do several things right - without caring
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about losing support for old boards.
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General features include:
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- A posix based file API
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Features
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inside barebox the usual open/close/read/write/lseek functions are used.
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--------
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- A POSIX based file API
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Inside barebox the usual open/close/read/write/lseek functions are used.
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This makes it familiar to everyone who has programmed under unix systems.
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This makes it familiar to everyone who has programmed under unix systems.
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- usual shell commands like ls/cd/mkdir/echo/cat,...
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- Usual shell commands like ls/cd/mkdir/echo/cat,...
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- The environment is not a variable store anymore, but a file store. It has
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- The environment is not a variable store anymore, but a file store. It has
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currently some limitations, of course. The environment is not a real
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currently some limitations, of course. The environment is not a real
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@ -24,7 +21,7 @@ General features include:
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saves the files under a certain directory (by default /env) in persistent
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saves the files under a certain directory (by default /env) in persistent
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storage (by default /dev/env0). There is a counterpart called loadenv, too.
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storage (by default /dev/env0). There is a counterpart called loadenv, too.
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- Real filesystem support
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- filesystem support
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The loader starts up with mounting a ramdisk on /. Then a devfs is mounted
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The loader starts up with mounting a ramdisk on /. Then a devfs is mounted
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on /dev allowing the user (or shell commands) to access devices. Apart from
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on /dev allowing the user (or shell commands) to access devices. Apart from
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these two filesystems there is currently one filesystem ported: cramfs. One
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these two filesystems there is currently one filesystem ported: cramfs. One
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@ -72,10 +69,10 @@ General features include:
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except the ones really needed: moving the cursor and typing characters.
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except the ones really needed: moving the cursor and typing characters.
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Building barebox
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Building Barebox
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---------------
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----------------
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barebox uses the Linux kernel's build system. It consists of two parts:
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Barebox uses the Linux kernel's build system. It consists of two parts:
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the makefile infrastructure (kbuild), plus a configuration system
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the makefile infrastructure (kbuild), plus a configuration system
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(kconfig). So building barebox is very similar to building the Linux
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(kconfig). So building barebox is very similar to building the Linux
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kernel.
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kernel.
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@ -109,7 +106,7 @@ If everything goes well, the result is a file called barebox:
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# ls -l barebox
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# ls -l barebox
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-rwxr-xr-x 1 rsc ptx 114073 Jun 26 22:34 barebox
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-rwxr-xr-x 1 rsc ptx 114073 Jun 26 22:34 barebox
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barebox usually needs an environment for storing the configuation data.
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Barebox usually needs an environment for storing the configuation data.
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You can generate an environment using the example environment contained
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You can generate an environment using the example environment contained
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in examples/environment:
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in examples/environment:
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Specifying -[ie] <file> tells barebox to map the file as a device
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Specifying -[ie] <file> tells barebox to map the file as a device
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under /dev. Files given with '-e' will appear as /dev/env[n]. Files
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under /dev. Files given with '-e' will appear as /dev/env[n]. Files
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given with '-i' will appear as /dev/fd[n].
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given with '-i' will appear as /dev/fd[n].
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If barebox finds a valid configuration sector on /dev/env0 it will
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If barebox finds a valid configuration sector on /dev/env0 it will
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load it to /env. It then executes /env/init if it exists. If you have
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load it to /env. It then executes /env/init if it exists. If you have
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loaded the example environment barebox will show you a menu asking for
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loaded the example environment barebox will show you a menu asking for
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@ -149,9 +147,10 @@ Memory can be examined as usual using md/mw commands. They both understand
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the -f <file> option to tell the commands that they should work on the
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the -f <file> option to tell the commands that they should work on the
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specified files instead of /dev/mem which holds the complete address space.
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specified files instead of /dev/mem which holds the complete address space.
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Note that if you call 'md /dev/fd0' (without -f) barebox will segfault on
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Note that if you call 'md /dev/fd0' (without -f) barebox will segfault on
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the host, because it will interpret /dev/fd0 as a number.
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the host, because it will interpret /dev/fd0 as a number.
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Directory layout
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Directory Layout
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Most of the directory layout is based upon the Linux Kernel:
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Most of the directory layout is based upon the Linux Kernel:
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@ -180,4 +179,5 @@ net/ -> Networking stuff
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scripts/ -> Kconfig system
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scripts/ -> Kconfig system
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Documentation/ ->
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Documentation/ -> Doxygen generated documentation
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