54 lines
2.2 KiB
Text
54 lines
2.2 KiB
Text
|
Information related to variable support in ELILO
|
||
|
|
------------------------------------------------
|
||
|
|
(c) 2002-2003 Hewlett Packard Co
|
||
|
|
Contributed by Stephane Eranian <eranian@hpl.hp.com>
|
||
|
|
|
||
|
|
Last updated: 06/13/2002
|
||
|
|
|
||
|
|
As of version 3.2, elilo has internal variables which can be programmed
|
||
|
|
by any module inside the bootloader code. These variables are used
|
||
|
|
to parametrize some of the arguments passed on the kernel command line.
|
||
|
|
|
||
|
|
The value of a variable is a Unicode string. Variables names are composed
|
||
|
|
of a single Unicode character, such as 'I' for instance. Variable names
|
||
|
|
are case sensitive. Elilo has support for 52 variables: A-Z and a-z.
|
||
|
|
|
||
|
|
The '%' sign is used to name a variable. For instance, '%I' indicates
|
||
|
|
variable 'I'. If '%I' is present on the command line to the kernel,
|
||
|
|
it will be replaced (string replacement) with the value (a string) of 'I'.
|
||
|
|
By default, the Elilo core does not assign any values to any variables.
|
||
|
|
It is up to each module to do so. When a variable is not used, its content
|
||
|
|
is the empty string "", which means that the '%d' notation, for instance, will
|
||
|
|
be replaced with the empty string.
|
||
|
|
|
||
|
|
Let us look at an example:
|
||
|
|
Supposing that the following variables are defined:
|
||
|
|
'I' -> "192.168.2.5"
|
||
|
|
'G' -> "192.168.2.1"
|
||
|
|
'M' -> "255.255.255.0"
|
||
|
|
'z' -> ""
|
||
|
|
|
||
|
|
Then a command line of this form (provided as an append= option in elilo.conf):
|
||
|
|
|
||
|
|
root=/dev/nfs nfsroot=15.4.88.178:/mnt2 ip=%I:%z:%G:%N:jung:eth0:on
|
||
|
|
|
||
|
|
Would pass the following to the kernel:
|
||
|
|
|
||
|
|
root=/dev/nfs nfsroot=15.4.88.178:/mnt2 ip=192.168.2.5::192.168.2.1:255.255.255.0:jung:eth0:on
|
||
|
|
|
||
|
|
Of course, the meaning of each variable is up to each individual module, the
|
||
|
|
names used here are not necessarily representative of the actual names used
|
||
|
|
by elilo.
|
||
|
|
|
||
|
|
Some choosers, (such as simple) have support to print the list of
|
||
|
|
defined variables. For instance, in simple (the default chooser) you
|
||
|
|
can press '%' to see the list of defined variables.
|
||
|
|
|
||
|
|
Variables can be useful when netbooting, for instance, to get the
|
||
|
|
dynamically assigned IP, netmask, and gateway addresses.
|
||
|
|
|
||
|
|
In case the % character needs to be passed to the kernel, it is possible
|
||
|
|
to "despecialize" a character using the & symbol in front of it.
|
||
|
|
|
||
|
|
See netbooting.txt for more information on this.
|