Hardware/ARMEBS/3/LinuxCommandLine

Linux command line

The Linux command line can be used to change default behaviour of the kernel, for the ARMEBS3 board, the linux command line is set by Hardware/ARMEBS/3/u-boot

(Uncomplete) list of useful options

root

Set the root filesystem device (see RootFileSystem)

console

Set the console device 'console=ttyS0,115200' for console on the first serial port @115200 bauds or 'console=tty' for console on the video out. This can be used many times, 'console=ttyS0,115200 console=tty' for console on ttyS0 and on the video output, but the console input and messages after kernel has started are only on the first (in this case, ttyS0).

init

Change wich execuatble is run by the kernel after initialization, init=/bin/bash will run bash, default : init=/sbin/init

nfsroot

Options used with root=/dev/nfs (see RootFileSystem#NFS)

mem

Override the amount of RAM given by the bootloader to the kernel. This is usefull to check if a complete system can run with less RAM, for decreasing production cost... example: mem=8M to restrict ram to 8 megabytes

video

Set the video output (default:video=s1d13x06fb:crt,mode:800x600-16)

 example: video=s1d13x06fb:lcd,mode:640x480-16 

mezza_lcd

Is it possible to use many mezza_lcd at the same time. This parameter is used to set how the configuration switch on mezza_lcd are configured. By default, only one card is supported, using the switch on position 0x5. /dev/fbX device are allocated in the order they appear. Interrupt sharing is possible, but each mezza_lcd MUST use a different chip select. Example parameter for supporting 2 mezza_lcd, one with the switch on the 0x9 position and another with the switch on the 0x5 position. The card with the switch on 0x9 will be /dev/fb0 and the card with the 0x5 position will be /dev/fb1

 example : 'mezza_lcd=0x9,0x5' 

ANY_UNUSED_OPTION

Any unused option (not used by the kernel) is used to set environment of the Linux system, for instance, if you add TOTO="hello world" in the kernel command line, you can use this in a shell script :

 pim@devmachine ~ > echo $TOTO
 hello world
 pim@devmachine ~ >

Note

The command line can be read from userland in the /proc/cmdline pseudo-file

Example :

 pim@devmachine ~ > cat /proc/cmdline
 init=/bin/bash mem=128M console=ttyS0,115200 TOTO="hello world" root=/dev/nfs rw nfsroot=153.109.5.233:/opt/armebs3/nfs ip=153.109.5.232:153.109.5.233:153.109.5.1:255.255.255.0::eth0:off 
 pim@devmachine ~ >