elilo/docs/simple_chooser.txt

Information about the simple chooser
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Copyright (C) 2002-2003 Hewlett-Packard Co.
Contributed by Stephane Eranian <eranian@hpl.hp.com>

Last updated: 02/02/14

Chooser name: simple
Command line option: -C simple
Config file option: chooser=simple, description, message

The simple chooser is the default chooser. However it is possible
to disable it at compile time, it is highly recommended to keep it
in. Elilo must have at least one chooser compiled in.

The simple chooser is very basic as its name indicates! It provides
a simple one line text mode command prompt similar to what you get
with Lilo/x86.  

Any chooser becomes visible to the user ONLY when the interactive
mode is entered.

The simple chooser allows the user to select a kernel to boot.
The user can use a label as specified in the elilo config file 
or a kernel file name. File names can be specified with
absolute names in the form dev_name:/path/to/my_kernel.

1/ Activation

   The chooser is activated from:

   	- command line  with the -c simple
	- the config file with the chooser=simple option

2/ Supported options

   The simple chooser supports the following options in the config file:

   	message=filename  : display a message before the prompt. The filename
			    must be an ASCII file

	description=string: a description of the kernel image (ASCII)

   All other options have their standard meaning. The chooser does not recognize 
   the fX (X varies from 1-12) options

2/ Builtin commands
   
The simple chooser has some builtin command which the user can
get to by typing certain keys as the first character on the command line:

    TAB: 	shows the list of defined labels and their descriptions.

		If the user did not type anything, i.e., the line is empty,
		pressing TAB will print the list of labels defined in the
		elilo config file.

		If the user already typed a name and if the name corresponds
		to a specified label, the chooser will show how the label
		is expanded and what the final command line to the kernel will
		look like.

		If the line is empty pressing TAB generates something similar to:
		ELILO boot: 
		linux-up linux nfsroot   (or any kernel file name: [dev_name:]/path/file)

		Note that first label correspond to the default label used if the user
		hits the enter key with an empty line. This label is not necessarily
		the first one in the config file.

		Now pressing TAB with a full label name:

		ELILO boot: linux-up
		desc   : my default UP kernel
		cmdline: vmlinuz root=/dev/sdb2 console=ttyS0,115200n8 console=tty0 ro

		The desc line shows whatever was specified in the "description" option 
		for this particular image in the config  file.

    =  :	shows the list of accessible devices

    		this key force elilo to print the list of detected devices. Elilo will 
		auto-detect the devices which are accessible to load a config file, the kernel, the
		initrd from. Those devices typically represent disk partition, CDROM, floppy, or
		a network path. The list of devices is highly system dependent.
		It also depends on the filesystem support compiled into elilo.

		The way the devices are named depends on the device naming scheme
		selected. It also depends on whether the EDD30 support is activated.
		For instance, pressing the ? could look as follows:

		ELILO boot: 
		scsi0 :   vfat : Acpi(PNP0A03,2)/Pci(1|0)/Scsi(Pun0,Lun0)/HD(Part1,Sig72040800)
		scsi1 :   vfat : Acpi(PNP0A03,2)/Pci(1|0)/Scsi(Pun6,Lun0)/HD(Part1,Sig00000000)
		scsi2 : ext2fs : Acpi(PNP0A03,2)/Pci(1|0)/Scsi(Pun0,Lun0)/HD(Part2,Sig72040800)
		scsi3 : ext2fs : Acpi(PNP0A03,2)/Pci(1|0)/Scsi(Pun6,Lun0)/HD(Part2,Sig00000000)
		net0 :  netfs : Acpi(PNP0A03,0)/Pci(5|0)/Mac(00D0B7A6FC25)
		5 devices available for booting
		boot device net0: netfs

		Here the vfat (EFI partition type), ext2fs and network filesysten (not to be confused
		with NFS) were compiled into elilo and were detected on the machine. The left handside
		of the colon show the logical name associated with the device. For instance,
		scsi0 corresponds to the first partition of SCSI disk ID 0 and is an EFI partition.
		The net0 correspond to a network device, here the Ethernet adapter. The last line
		show the device used to load elilo itself, in the case elilo was downloaded from the
		network.

		To get a kernel from scsi0, the user can simply type:

			ELILO boot: scsi0:/usr/src/linux/vmlinux 

		Note that even though elilo was not downloaded from the network, it is still possible
		to get the kernel and initrd from a remote machine.

    %  :	shows the list of defined variables

    		Elilo has builtin variables which are used to dynamically customized the command line
		parameters passed to the kernel. The list of variables depends on the support compiled
		into elilo. Not all elilo subsystems use variables. Typically the network file system
		does. Pressing '%' only prints the variables that are defined with their current values.
		Some variables are only defined once the subsystem that creates them has been used.
		In other words, if the network filesystem was not used to load elilo, then the variables
		defined by it are not created.

		If the network was actually used, pressing '%' could generate the following output:
		ELILO boot:     
		D = "mydomain.com
		G = "192.168.3.1"
		H = "test_machine"
		I = "192.168.3.4"
		M = "255.255.255.0"

    &  :	shows the list default path

    		The path is used as a prefix for all filenames specified as
		relative.

    ?  :	shows the list of supported command keys


The simple chooser has also some builtin command line editing commands:

 	ESC	 : abort (leave elilo)

	CTRL-D   : abort (leave elilo)

	CTRL-C	 : kill line
		   empty current line and prompt for new input

	CTRL-H   : erase the previous character

	CTRL-U	 : clear current line
		   reset the buffer (does not display correctly if buffer spans more than one line)

	Backspace: erase character