Dave Embedded Systems SBC AXEL, Руководство пользователя

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S B C X U s e r ' s G u i d e v . 1 . 0 . 1
commands. U-Boot manages an environment space where several
variables can be stored. These variables are extremely useful to
permanently save system settings (such as ethernet MAC address) and
to automate boot procedures. This environment is redundantly stored in
two physical sectors of boot flash memory; the default variables set is
hard-coded in the source code itself. User can modify these variables
and add new ones in order to create his/her own custom set of
configurations. The commands used to do that are
setenv
and
saveenv
. This process allows the user to easily set up the required
configuration. Once U-Boot prompt is available, it is possible to print the
whole environment by issuing the command
printenv
.
For further information on use of U-Boot, please refer to
http://www.denx.de/wiki/view/DULG/UBoot
7.3.2.3 Kernel
Linux kernel for i.MX processors is maintained primarily by NXP /
Freescale. Periodically NXP / Freescale releases the so-called Linux
BSP, which provides updated kernel sources.
Kernels released within XELK derive directly from NXP / Freescale Linux
BSP kernels.
7.3.2.4 Linux Device Tree
The Flattened Device Tree (FDT) is a data structure for describing the
hardware in a system (for further information, please refer to
http://elinux.org/Device_Tree
). Device tree source code is stored into
the
arch/arm/boot/dts/
directory.
7.3.2.5 Target root file system
The Linux kernel running on the target needs to mount a root file system.
Building a root file system from scratch is definitively a complex task
because several well known directories must be created and populated
with a lot of files that must follow some standard rules. Again we will use
pre-packaged root file systems that make this task much easier.
However, using a build tool as Yocto, developers can build their own
version of the root file system.
7.3.2.6 Yocto
The Yocto Project, hosted by the Linux Foundation, provides open
source, high-quality infrastructure and tools to help developers create
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