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2 ELILO.EFI: Linux boot loader for EFI/IA-64 and EFI/IA-32 based systems
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4 Stephane Eranian <eranian@hpl.hp.com>
8 Copyright (C) 2000-2003 Hewlett-Packard Co.
14 This document describes how to use ELILO on for both IA-64 and IA-32 EFI-based platforms.
15 This document describes ELILO version 3.4.
17 II/ Command line options
20 elilo [-hDpPVvaE] [-d nsec] [-C config] [-i initrd] [-c chooser] [kernel [kernel options...]]
22 -h Display a list of all possible command line options.
24 -V Print the version number and exit.
26 -d nsec Specify the number of 10th of seconds before loading the
29 -C file Specify the config file to use. The default is elilo.conf in the directory
30 that elilo.efi was loaded from.
32 -P Verify config file syntax only. this option causes ELILO to
33 parse the config file and generate a report on the console.
36 -v Turn on verbose mode. ELILO prints more message about what it
37 is doing. For each occurrence of this option the verbosity level
38 is increased by one. The maximum level is 5.
40 -a Always check for alternate kernel image. The default behavior
41 of ELILO is to NOT look for an alternate image. This
42 option overrides this behavior and ELILO is checking for
43 alternate images no matter what. Alternate images are
44 specified using the EliloAlt EFI variable.
46 -p force interactive prompt mode. Valid when no kernel image is
47 specified on the command line.
49 -D print debug output.
51 -E don't force EDD30 variable to TRUE when FALSE.
53 -i file Use file as the initial ramdisk (initrd).
55 -c name Specify which kernel chooser to use. Default is 'simple', and
56 the only other choice at present is 'textmenu'.
58 In addition, elilo supports platform specific options:
62 -r the kernel image can be relocated if initial load address is not
63 available. This options requires a special version of the kernel.
65 -F file will try to load the FPSWA driver indicated by 'file'. Only this file
66 will be attempted. When no specific file is given, elilo will try
67 loading \efi\intel firmware\fpswa.efi from all accessible EFI system
73 All file names (including the kernel file) can include a device name using the
76 dev_name:/path/to/my/kernel
78 The 'dev_name' component depends on the naming scheme selected and the detected
79 devices for your system. Some choosers may print the information automatically
80 or on demand, see chooser specific documentation for more on this. See README.devschemes
81 for more information on device naming schemes. The slash character '/' can be used as
82 a directory separator on any file systems including the EFI file system (FAT32).
85 III/ Configuration File
88 ELILO supports a config file with options similar to the LILO/x86 boot loader.
90 Elilo will use the following sequence (shown in order) when looking for its config
91 file when none is specified on the command line:
93 1/ AABBCCDD.conf (netbooting with regular DHCP)
94 where AABBCCDD is the hexadecimal representation
95 of the IP address assigned during the DHCP phase.
97 2/ elilo-ia64.conf or elilo-ia32.conf
98 The choice depends on the client platform. This step allows
99 the same DHCP/PXE server to provide files for both types of clients.
103 Unless explicitly specified on the command line, elilo looks for its config file
104 in the filesystem and directory it was loaded from. For instance, if elilo.efi
107 fs0:\> \efi\debian\elilo.efi
109 Then elilo will look for its configuration file in fs0:\efi\debian and not
110 in the root directory of fs0:. The prefix fs0:\efi\debian will be used for
111 all other files that elilo needs to download when their paths are specified
115 This rule also applies when a specific config file is passed via the -C
118 fs0:\> \efi\debian\elilo.efi -C elilo.conf
120 This will look for elilo.conf in fs0:\efi\debian and not in fs0:\.
121 To get to the elilo.conf in fs0:\, you need to specify the absolute
124 fs0:\> \efi\debian\elilo.efi -C \elilo.conf
127 The configuration file is an ASCII file and not a UNICODE file.
129 The config file contains additional options to change the behavior of the loader.
130 If the same option is specified in the config file AND on the command line, the
131 latter takes precedence. Not all options available in the config file have an
132 equivalent on command line.
134 When elilo is invoked with the -h option, it prints the list of support command line
135 options but also the list of config file options. For each option it also prints
136 the type of data expected.
138 The config file options are divided in 2 groups:
141 - image options which are specific to a particular kernel image. Each kernel image
142 must be identified with a logical name called a label.
144 - global options which affect the behavior of ELILO and apply to all images.
146 The ELILO config file follows the LILO/x86 syntax. First come the global
147 options, then the list of images and options for each of them, if
148 necessary. At least one image MUST be defined and it is possible to have
149 an empty list of global options.
151 Options have types. Three types are defined:
152 - boolean: set or not set
153 - string : a string of characters which can be quoted if necessary
154 - number (in decimal)
155 - filename: a string interpreted as a file name
158 The config file supports the following options:
162 default=value Name the default image to boot. If not defined ELILO
163 will boot the first defined image.
165 timeout=number The number of 10th of seconds to wait while in
166 interactive mode before auto booting default kernel.
169 delay=number The number of 10th of seconds to wait before
170 auto booting when not in interactive mode.
173 prompt Force interactive mode
175 verbose=number Set level of verbosity [0-5]. Default 0 (no verbose)
177 root=filename Set global root filesystem for Linux/ia64
179 read-only Force root filesystem to be mounted read-only
181 append=string Append a string of options to kernel command line
183 initrd=filename Name of initrd file
185 image=filename Define a new image
187 chooser=name Specify kernel chooser to use: 'simple' or 'textmenu'.
189 message=filename a message that is printed on the main screen if supported by
192 fX=filename Some choosers may take advantage of this option to
193 display the content of a file when a certain function
194 key X is pressed. X can vary from 1-12 to cover
195 function keys F1 to F12.
197 noedd30 do not force the EDD30 EFI variable to TRUE when FALSE. In other
198 words, don't force the EDD30 mode if not set.
202 root=filename Set root filesystem for kernel
204 read-only Force root filesystem to be mounted read-only
206 append=string Append a string of options to kernel command line
208 initrd=filename Name of initrd file
210 label=string Logical name of image (used in interactive mode)
212 description=string One line text description of the image.
214 IA-64 specific options:
215 -----------------------
219 fpswa=file Specify the filename for a specific FPSWA to load.
220 If this option is used then no other file will be tried.
222 relocatable In case of memory allocation error at initial load point of
223 kernel, allow attempt to relocate (assume kernels is relocatable)
227 relocatable In case of memory allocation error at initial load point of
228 kernel, allow attempt to relocate (assume this kernel is relocatable)
230 IA-32 specific options:
231 -----------------------
232 legacy-free Indicate that the host machine does not have a legacy BIOS at all.
235 The user can specify a kernel and related kernel options using the image label. Alternatively,
236 the user can also specify a kernel file that is not specified in the config file. In any case,
237 some of the global options (such as append) are always concatenated to whatever the user type.
240 IV/ Booting from the local system
241 -----------------------------
243 The elilo.efi binary must be in an EFI system partition (FAT32). The config
244 file, kernel image, and optional initrd ramdisk can be on the same partition
245 or even another EFI partition. In the following discussion we assume that all
246 files are on the same EFI partition which is recognized by the EFI shell (nshell)
247 as fs0. The kernel and initrd can be copied from the any linux filesystems to the
248 EFI partition using either the mtools (mcopy) or by mounting the EFI partition as
249 a vfat partition. However you do not really need this because most linux
250 distributions install both files in the EFI partition and mount this partition in /boot/efi.
252 To boot a kernel, simply power cycle the machine. Once you get to the EFI
253 shell prompt, change to the filesystem that maps to the partition where elilo is.
258 You might need to make sure that the Shell Path is set such that it will load
259 ELILO from fs0:. You can verify this by typing:
263 At this point you can invoke ELILO:
267 If there is no config file, then it will:
268 - pick up the kernel image named vmlinux if it exists, otherwise it will abort.
269 - pass no argument to the kernel.
271 You can specify the kernel image and its options on the command line.
272 For instance you can do:
274 fs0:\> elilo vmlinux root=/dev/sda5
276 You can specify as many parameters as you want. The syntax follows the kernel
277 rule, i.e., list of value pairs (or even single values) separated by space.
278 A more complicated example would be:
280 fs0:\> elilo -i initrd-2.4.9 vmlinuz-2.4.9 root=/dev/sda2 console=tty0 console="ttyS0,115200n8"
282 In this example, notice the double quotes. They are required because the comma is a control
283 character for nshell.
285 In the case a config file is found, then elilo will behave according to
286 the options in that file. However if elilo is invoked with command line options, they
287 will be combined or they will override (if conflicting) what is defined in the config file.
289 As of version 3.3, elilo is fully compliant with the EFI specification (1.10) with regards
290 to where the bootloader (elilo.efi) must be located in the EFI system partition. In
291 section 11.2.1.3 of the EFI1.10 specification, it is said that in order to avoid conflicts
292 between various loaders for various OSes or distributions of the same OS, every vendor MUST
293 use a dedicated directory: \EFI\vendor\. The bootloader must be placed in this directory.
294 This has always been possible as this is a matter of creating the directory and copying
295 the elilo.efi file in it. However up until version 3.3, elilo would look for its config file
296 and kernel/initrd in the root (/) of the partition it was loaded from. As of version 3.3,
297 elilo will now ONLY look for its configuration file FROM THE DIRECTORY IT WAS LOADED FROM.
298 The same applies to the kernel and initrd files unless absolute paths are specified. Let us
299 look at a simple example:
301 - suppose elilo.efi is in \EFI\DIST if fs0: (for the EFI Shell)
303 - if you invoke elilo as follows:
305 fs0:\> \efi\dist\elilo -v -p
306 default file path: \efi\dist\
307 config file : \efi\dist\elilo.conf
311 Note that this is the same if you invoke elilo directly from \efi or \efi\dist.
313 File references in the configuration file are treated as relative to the directory
314 elilo was loaded from except if they use an absolute path.
316 As of version 3.4 a similar rule applies to the network boot sequence, see netbooting.txt
322 Elilo can be forced into interactive mode using the "prompt" option in the config
323 file or with the -p option. In this mode, the user can select a kernel to load.
325 The interface depends on the chooser, it may be a simple command line prompt as provided
326 by the simple chooser or a more sophisticated screen with scroll menus as provided by
327 textmenu. Most choosers depends on the elilo config file to get the information they
328 display. The simple chooser can operated without the elilo config file. However it
329 is always better to have this file, to create handy logical names for each possible
330 boot choices. The logical names are specified with the "label" option in the config
331 file. They represent a specific kernel "image" and its specific options.
333 In elilo, the user can select a particular kernel image using the corresponding label
334 name. A simple example is as follows:
336 If we suppose that the following is defined in elilo.conf:
342 append="console=tty0 console=ttyS0,115200n8"
344 then the user can specify linux-up at the prompt and elilo will load the
345 vmlinuz-2.4.9 kernel file and the initrd-2.4.9 ramdisk and will pass
347 "root=/dev/sda2 console=tty0 console=ttyS0,115200n8"
349 as command line arguments to the kernel.
351 This behavior is identical to Lilo/x86. However, elilo further allows the user
352 to specify actual kernel files names as well, i.e., kernels that are not defined
353 in the configuration file. If we reuse the above example and the simple chooser,
356 ELILO boot: vmlinux-2.4.18 root=/dev/sda2
358 and elilo will boot the vmlinuz-2.4.18 kernel if it exists.
360 VI/ The alternate kernel image
361 --------------------------
363 Oftentimes when debugging kernels you want to reboot the machine once with
364 your test kernel and, if something goes wrong, you want to fall back to a more
365 stable kernel. In addition you want to be able to do this from a remote machine.
366 Many things can go wrong when doing kernel debugging. It could be that you don't
367 even reach user-mode. In this case however, you still want to fall back to
368 a stable kernel. The feature you'd like from a boot loader is 'boot once and
369 then fall back to safe kernel'.
371 Elilo offers this feature and it's called 'alternate kernel image'.
372 You can configure elilo to load a kernel only once and then whatever
373 happens the next reboot falls back to a different kernel hopefully more stable.
375 To do this, elilo relies on an EFI variable called 'EliloAlt' with a NULL GUID.
376 The content of this variable is a UNICODE string containing the kernel file name
377 and its command line options.
379 When the -a option is specified on the command line or if the "checkalt" option
380 is present in the config file, elilo will check for the presence of this variable.
381 If found and the content is a valid UNICODE string, elilo will use it as the kernel
382 to boot. There is no verification made on the validity of the kernel name or options.
383 Then the variable is deleted. If the variable is rejected because it does not look
384 sane, it is also deleted.
386 The variable can be set from a running Linux system using the /proc/efi/vars
387 interface. In the tools directory of this package, there is a Linux tool called
388 elilovar which can be used to create, modify, print, and delete the EliloAlt
389 variable. Refer to eliloalt.txt for more information on this tool.
391 VII/ Auto booting the machine
392 -----------------------
394 Once you're satisfied with your machine setup, it is good to install an
395 auto boot procedure. You have two options to do this:
396 - from the EFI boot manager menu
399 The first option is preferred and is used by most Linux distributions.
400 Elilo can be invoked directly from the boot manager. You need to get into
401 the 'boot maintenance' menu and use load file a file. This can be tedious
402 so instead it is recommended that you use a Linux tool called efibootmgr
403 which is also shipped in most distributions. With this tool, you can
404 create your own boot option and change the boot order.
408 The second approach use the EFI shell and a shell script with a special name: 'startup.nsh'.
410 When the system boots, it looks for EFI partitions and if it finds
411 a 'startup.nsh' file in ANY of these it will jumpstart execution from it.
413 So the typical way of auto booting your Linux/ia64 system is to simply create
414 such a file with the following content:
416 # cat /boot/startup.nsh
417 elilo vmlinuz root=/dev/sda2
419 Of course, this can be simplified if there is a configuration file.
425 Please refer to netbooting.txt for a complete description of how to boot
429 XII/ Booting on EFI/ia32 platforms
430 -----------------------------
432 Until PC comes with the EFI firmware built in, you need to boot from a
433 floppy that has the EFI firmware on it. Such floppy can be
434 constructed from the EFI sample implementation and toolkit that is
435 available from the Intel Developer Web site at:
437 http://developer.intel.com/technology/efi/
439 To use elilo on IA-32, you can put it on a floppy and
440 on a FAT32 partition (msdos partition). You can also
441 netbooting if you network adapter has support for UNDI/PXE.
443 Elilo/ia32 is capable of booting unmodified 2.2.x. and 2.4.x kernels
444 as they are shipped by distributors today (such as Redhat7.2). You don't need
445 to recompile the kernel with special options. Elilo ONLY takes compressed kernel
446 image which are typically obtained via a 'make bzImage'. Plain elf/32 kernel can't
447 be booted (plain vmlinux will not work). Similarly, existing initial ramdisks can
448 be used without modifications.
454 Stephane Eranian <eranian@hpl.hp.com>
455 David Mosberger <davidm@hpl.hp.com>
456 Johannes Erdfelt <jerdfelt@valinux.com>
457 Richard Hirst <rhirst@linuxcare.com>
458 Chris Ahna <christopher.j.ahna@intel.com>
459 Mike Johnston <michael.johnston@intel.com>
464 You can submit bugs to <eranian@hpl.hp.com> or to the Linux/ia64
465 mailing list at linux-ia64@linuxia64.org. Visit http://www.linuxia64.org
466 to subscribe to this list.
471 EFI v1.02 specifications are available from the following web site:
473 http://developer.intel.com/technology/efi/
475 The latest sources of ELILO can be downloaded at:
477 ftp://ftp.hpl.hp.com/pub/linux-ia64