GUF-Yocto-jethro-9.0-r7707-0
i.MX6
User Manual
4.2.3 Reboot, Halt and Poweroff
As you probably have noticed already, none of our Garz & Fricke devices are equipped with any kind of power-
button. This means, they will start booting and running an OS as soon as an external power-supply is connected
and turned-on and the only way to turn the device off is to turn off the external power-supply.
The devices are not designed to be turned-off under software-control.
The common Unix/Linux utilities to shutdown the system behave accordingly:
reboot
: will stop all login-services, stop all running applications, flush all caches, unmount all filesystems
and safely reboot the system.
halt
: will stop all login-services, stop all running applications, flush all caches, unmount all filesystems and
just "halt" the system, so that a user may safely disconnect the power-supply without risking any data-loss.
poweroff
: according to Unix/Linux conventions for systems, that cannot turn-off themselves, will do just
the same as
halt
.
This means, as per Linux/Unix convention for systems, that can’t turn-off themselves, none of these commands
will turn-off device power; not even the display power. The
halt-
and
poweroff-
commands will only ensure that
the system is put in a state, where no user-processes are running anymore and all data has been written back to
storage media.
If you’d like to, e.g. turn-off the display, when the
halt-
and
poweroff-
commands are issued, you may do so
yourself using a start/stop-script as described in
[
I
.
4.2.4 Kernel command line
The kernel command line can be used to change some kernel features.
Note:
Be careful changing the command line, as it can easily break the booting process of your
device. If booting fails after those changes, you will need to boot into
Flash-N-Go System
and correct
the settings. In this case, please refer to the
Flash-N-Go System
manual.
To change the kernel command line, the boot partition needs to be mounted.
mount /dev/mmcblk0p2 /mnt
Calling
nano /mnt/boot.cfg
will bring up the editor with the boot configurations.
The boot configuration normally looks similar to this:
load -b 0x13000000 -p config config.xml
load -b 0x13080000 -o logo.png
devtree -b
0x05:0x61:0x13040000 imx6-santoka-dl.dtb
devtree -b
0x05:0x63:0x13040000 imx6-santoka-q.dtb
devtree -b
0x07:0x61:0x13040000 imx6-santaro-dl.dtb
devtree -b
0x07:0x63:0x13040000 imx6-santaro-q.dtb
load linuximage
exec "console=ttymxc0,115200 root=/dev/mmcblk0p3 xmlram=0x13000000 logo=0x13080000"
The last line is the kernel command line. Options can be added to the end.
Example 1:
Enable the SPI interface on the keypad connector:
exec "console=ttymxc0,115200 root=/dev/mmcblk0p3 xmlram=0x13000000 logo=0x13080000
,!
keypad=gpio,spi"
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