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@@ -28,14 +28,16 @@ The Linux kernel in OpenADK is intended to be very small in size and will
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be by default compressed with xz compression algorithm, if available for
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the target system. You can configure the compression algorithm used for the
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compression of the Linux kernel and if choosen the initramfs filesystem in
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-+make menuconfig+. In +Kernel configuration+ you have the choice between
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-dfferent kernel versions. The latest stable OpenADK version will be automatically used.
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++make menuconfig+. In +Linux Kernel configuration+ you have the choice between
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+dfferent kernel versions. Depending on your target devices, their might
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+be some external git repositories available, if the support for the device
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+is not upstream.
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There you can choose any needed addon drivers or any supported runtime
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and debugging features.
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The kernel expands itself on boot, if compressed, and then initialize the
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-hardware. The additional kernel modules are loaded later by a init script.
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-The kernel will autoamtically mount the virtual filesystem /dev as devtmpfs
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+hardware. The additional kernel modules are loaded later by an init script.
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+The kernel will automatically mount the virtual filesystem /dev as devtmpfs
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and then will execute +/sbin/init+ in userspace.
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init system
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@@ -46,10 +48,11 @@ carries the PID number 1), and is responsible for starting the userspace
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services and programs (for example: web server, graphical applications, other
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network servers, etc.).
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-OpenADK uses *Busybox* init. Amongst many programs, Busybox has an
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-implementation of a basic +init+ program, which is sufficient for most embedded
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-systems. The Busybox +init+ program will read the +/etc/inittab+ file at boot
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-to know what to do. The syntax of this file can be found in
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+In OpenADK you can choose between different init implementations. *Busybox*
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+init is the best tested one and the default. Amongst many programs, Busybox
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+has an implementation of a basic +init+ program, which is sufficient for most
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+embedded systems. The Busybox +init+ program will read the +/etc/inittab+ file
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+at boot to know what to do. The syntax of this file can be found in
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http://git.busybox.net/busybox/tree/examples/inittab (note that Busybox
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+inittab+ syntax is special: do not use a random +inittab+ documentation from
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the Internet to learn about Busybox +inittab+). The default +inittab+ in
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@@ -57,6 +60,8 @@ OpenADK is generated while producing the +base-files+ package. The main job
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the default inittab does is to start the +/etc/init.d/rcS+ shell script, and
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start one or more +getty+ programs (which provides a login prompt).
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+Support for systemd and s6 is very experimental at the moment.
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+
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/dev management
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~~~~~~~~~~~~~~~
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@@ -67,19 +72,20 @@ files_, your userspace applications would not be able to use the
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hardware devices, even if they are properly recognized by the Linux
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kernel.
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-OpenADK uses *dynamic device nodes using devtmpfs and mdev*. This method relies
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-on the _devtmpfs_ virtual filesystem in the kernel, which is enabled by default
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-for all OpenADK generated kernels, and adds the +mdev+ userspace utility on top
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-of it. +mdev+ is a program part of Busybox that the kernel will call every time
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-a device is added or removed. Thanks to the +/etc/mdev.conf+ configuration
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-file, +mdev+ can be configured to for example, set specific permissions or
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-ownership on a device file, call a script or application whenever a device
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-appears or disappear, etc. Basically, it allows _userspace_ to react on device
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-addition and removal events. +mdev+ is also important if you have devices that
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-require a firmware, as it will be responsible for pushing the firmware contents
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-to the kernel. +mdev+ is a lightweight implementation (with fewer features) of
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-+udev+. For more details about +mdev+ and the syntax of its configuration file,
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-see http://git.busybox.net/busybox/tree/docs/mdev.txt.
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+In OpenADK you can choose between different types of device managements.
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+OpenADK defaults to *dynamic device nodes using devtmpfs and mdev*. This method
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+relies on the _devtmpfs_ virtual filesystem in the kernel, which is enabled by
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+default for all OpenADK generated kernels, and adds the +mdev+ userspace
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+utility on top of it. +mdev+ is a program part of Busybox that the kernel will
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+call every time a device is added or removed. Thanks to the +/etc/mdev.conf+
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+configuration file, +mdev+ can be configured to for example, set specific
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+permissions or ownership on a device file, call a script or application
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+whenever a device appears or disappear, etc. Basically, it allows _userspace_
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+to react on device addition and removal events. +mdev+ is also important if you
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+have devices that require a firmware, as it will be responsible for pushing the
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+firmware contents to the kernel. +mdev+ is a lightweight implementation (with
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+fewer features) of +udev+. For more details about +mdev+ and the syntax of its
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+configuration file, see http://git.busybox.net/busybox/tree/docs/mdev.txt.
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initscripts
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~~~~~~~~~~~
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@@ -141,7 +147,7 @@ manager (f.e. ipkg) will be reported.
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---------------------
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cfgfs
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-Configuration Filesystem Utility (cfgfs), Version 1.09
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+Configuration Filesystem Utility (cfgfs)
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Syntax:
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/sbin/cfgfs commit [-f]
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/sbin/cfgfs erase
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Waldemar Brodkorb