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wic: get rid of scripts/lib/image

Browse Source 
Moved content of scripts/lib/image/ to scripts/lib/wic as
one directory with the same name as a tool is self-explanatory
and less confusing than two.

(From OE-Core rev: 5dc02d572794298b3362378cea3d7da654456c44)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Ed Bartosh
2015-09-02 13:58:02 +03:00
committed by Richard Purdie
parent 77561e7191
commit 7d4bb40905
13 changed files with 5 additions and 27 deletions
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scripts/lib/wic/help.py
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# ex:ts=4:sw=4:sts=4:et
# -*- tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*-
#
# Copyright (c) 2013, Intel Corporation.
# All rights reserved.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# DESCRIPTION
# This module implements some basic help invocation functions along
# with the bulk of the help topic text for the OE Core Image Tools.
#
# AUTHORS
# Tom Zanussi <tom.zanussi (at] linux.intel.com>
#
import subprocess
import logging
from wic.plugin import pluginmgr, PLUGIN_TYPES
def subcommand_error(args):
logging.info("invalid subcommand %s" % args[0])
def display_help(subcommand, subcommands):
"""
Display help for subcommand.
"""
if subcommand not in subcommands:
return False
hlp = subcommands.get(subcommand, subcommand_error)[2]
if callable(hlp):
hlp = hlp()
pager = subprocess.Popen('less', stdin=subprocess.PIPE)
pager.communicate(hlp)
return True
def wic_help(args, usage_str, subcommands):
"""
Subcommand help dispatcher.
"""
if len(args) == 1 or not display_help(args[1], subcommands):
print usage_str
def get_wic_plugins_help():
"""
Combine wic_plugins_help with the help for every known
source plugin.
"""
result = wic_plugins_help
for plugin_type in PLUGIN_TYPES:
result += '\n\n%s PLUGINS\n\n' % plugin_type.upper()
for name, plugin in pluginmgr.get_plugins(plugin_type).iteritems():
result += "\n %s plugin:\n" % name
if plugin.__doc__:
result += plugin.__doc__
else:
result += "\n %s is missing docstring\n" % plugin
return result
def invoke_subcommand(args, parser, main_command_usage, subcommands):
"""
Dispatch to subcommand handler borrowed from combo-layer.
Should use argparse, but has to work in 2.6.
"""
if not args:
logging.error("No subcommand specified, exiting")
parser.print_help()
return 1
elif args[0] == "help":
wic_help(args, main_command_usage, subcommands)
elif args[0] not in subcommands:
logging.error("Unsupported subcommand %s, exiting\n" % (args[0]))
parser.print_help()
return 1
else:
usage = subcommands.get(args[0], subcommand_error)[1]
subcommands.get(args[0], subcommand_error)[0](args[1:], usage)
##
# wic help and usage strings
##
wic_usage = """
Create a customized OpenEmbedded image
usage: wic [--version] | [--help] | [COMMAND [ARGS]]
Current 'wic' commands are:
help Show help for command or one of the topics (see below)
create Create a new OpenEmbedded image
list List available values for options and image properties
Help topics:
overview wic overview - General overview of wic
plugins wic plugins - Overview and API
kickstart wic kickstart - wic kickstart reference
"""
wic_help_usage = """
usage: wic help <subcommand>
This command displays detailed help for the specified subcommand.
"""
wic_create_usage = """
Create a new OpenEmbedded image
usage: wic create <wks file or image name> [-o <DIRNAME> | --outdir <DIRNAME>]
[-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>]
[-e | --image-name] [-s, --skip-build-check] [-D, --debug]
[-r, --rootfs-dir] [-b, --bootimg-dir]
[-k, --kernel-dir] [-n, --native-sysroot] [-f, --build-rootfs]
This command creates an OpenEmbedded image based on the 'OE kickstart
commands' found in the <wks file>.
The -o option can be used to place the image in a directory with a
different name and location.
See 'wic help create' for more detailed instructions.
"""
wic_create_help = """
NAME
wic create - Create a new OpenEmbedded image
SYNOPSIS
wic create <wks file or image name> [-o <DIRNAME> | --outdir <DIRNAME>]
[-e | --image-name] [-s, --skip-build-check] [-D, --debug]
[-r, --rootfs-dir] [-b, --bootimg-dir]
[-k, --kernel-dir] [-n, --native-sysroot] [-f, --build-rootfs]
[-c, --compress-with]
DESCRIPTION
This command creates an OpenEmbedded image based on the 'OE
kickstart commands' found in the <wks file>.
In order to do this, wic needs to know the locations of the
various build artifacts required to build the image.
Users can explicitly specify the build artifact locations using
the -r, -b, -k, and -n options. See below for details on where
the corresponding artifacts are typically found in a normal
OpenEmbedded build.
Alternatively, users can use the -e option to have 'wic' determine
those locations for a given image. If the -e option is used, the
user needs to have set the appropriate MACHINE variable in
local.conf, and have sourced the build environment.
The -e option is used to specify the name of the image to use the
artifacts from e.g. core-image-sato.
The -r option is used to specify the path to the /rootfs dir to
use as the .wks rootfs source.
The -b option is used to specify the path to the dir containing
the boot artifacts (e.g. /EFI or /syslinux dirs) to use as the
.wks bootimg source.
The -k option is used to specify the path to the dir containing
the kernel to use in the .wks bootimg.
The -n option is used to specify the path to the native sysroot
containing the tools to use to build the image.
The -f option is used to build rootfs by running "bitbake <image>"
The -s option is used to skip the build check. The build check is
a simple sanity check used to determine whether the user has
sourced the build environment so that the -e option can operate
correctly. If the user has specified the build artifact locations
explicitly, 'wic' assumes the user knows what he or she is doing
and skips the build check.
The -D option is used to display debug information detailing
exactly what happens behind the scenes when a create request is
fulfilled (or not, as the case may be). It enumerates and
displays the command sequence used, and should be included in any
bug report describing unexpected results.
When 'wic -e' is used, the locations for the build artifacts
values are determined by 'wic -e' from the output of the 'bitbake
-e' command given an image name e.g. 'core-image-minimal' and a
given machine set in local.conf. In that case, the image is
created as if the following 'bitbake -e' variables were used:
-r: IMAGE_ROOTFS
-k: STAGING_KERNEL_DIR
-n: STAGING_DIR_NATIVE
-b: empty (plugin-specific handlers must determine this)
If 'wic -e' is not used, the user needs to select the appropriate
value for -b (as well as -r, -k, and -n).
The -o option can be used to place the image in a directory with a
different name and location.
The -c option is used to specify compressor utility to compress
an image. gzip, bzip2 and xz compressors are supported.
The set of properties available for a given image type can be
listed using the 'wic list' command.
"""
wic_list_usage = """
List available OpenEmbedded image properties and values
usage: wic list images
wic list <image> help
wic list source-plugins
wic list properties
wic list properties <wks file>
wic list property <property>
[-o <JSON PROPERTY FILE> | --outfile <JSON PROPERTY_FILE>]
This command enumerates the set of available canned images as well as
help for those images. It also can be used to enumerate the complete
set of possible values for a specified option or property needed by
the image creation process.
The first form enumerates all the available 'canned' images.
The second form lists the detailed help information for a specific
'canned' image.
The third form enumerates all the available --sources (source
plugins).
The fourth form enumerates all the possible values that exist and can
be specified in an OE kickstart (wks) file.
The fifth form enumerates all the possible options that exist for the
set of properties specified in a given OE kickstart (ks) file.
The final form enumerates all the possible values that exist and can
be specified for any given OE kickstart (wks) property.
See 'wic help list' for more details.
"""
wic_list_help = """
NAME
wic list - List available OpenEmbedded image properties and values
SYNOPSIS
wic list images
wic list <image> help
wic list source-plugins
wic list properties
wic list properties <wks file>
wic list property <property>
[-o <JSON PROPERTY FILE> | --outfile <JSON PROPERTY_FILE>]
DESCRIPTION
This command enumerates the complete set of possible values for a
specified option or property needed by the image creation process.
This command enumerates the set of available canned images as well
as help for those images. It also can be used to enumerate the
complete set of possible values for a specified option or property
needed by the image creation process.
The first form enumerates all the available 'canned' images.
These are actually just the set of .wks files that have been moved
into the /scripts/lib/wic/canned-wks directory).
The second form lists the detailed help information for a specific
'canned' image.
The third form enumerates all the available --sources (source
plugins). The contents of a given partition are driven by code
defined in 'source plugins'. Users specify a specific plugin via
the --source parameter of the partition .wks command. Normally
this is the 'rootfs' plugin but can be any of the more specialized
sources listed by the 'list source-plugins' command. Users can
also add their own source plugins - see 'wic help plugins' for
details.
The third form enumerates all the possible values that exist and
can be specified in a OE kickstart (wks) file. The output of this
can be used by the third form to print the description and
possible values of a specific property.
The fourth form enumerates all the possible options that exist for
the set of properties specified in a given OE kickstart (wks)
file. If the -o option is specified, the list of properties, in
addition to being displayed, will be written to the specified file
as a JSON object. In this case, the object will consist of the
set of name:value pairs corresponding to the (possibly nested)
dictionary of properties defined by the input statements used by
the image. Some example output for the 'list <wks file>' command:
$ wic list test.ks
"part" : {
"mountpoint" : "/"
"fstype" : "ext3"
}
"part" : {
"mountpoint" : "/home"
"fstype" : "ext3"
"offset" : "10000"
}
"bootloader" : {
"type" : "efi"
}
.
.
.
Each entry in the output consists of the name of the input element
e.g. "part", followed by the properties defined for that
element enclosed in braces. This information should provide
sufficient information to create a complete user interface with.
The final form enumerates all the possible values that exist and
can be specified for any given OE kickstart (wks) property. If
the -o option is specified, the list of values for the given
property, in addition to being displayed, will be written to the
specified file as a JSON object. In this case, the object will
consist of the set of name:value pairs corresponding to the array
of property values associated with the property.
$ wic list property part
["mountpoint", "where the partition should be mounted"]
["fstype", "filesytem type of the partition"]
["ext3"]
["ext4"]
["btrfs"]
["swap"]
["offset", "offset of the partition within the image"]
"""
wic_plugins_help = """
NAME
wic plugins - Overview and API
DESCRIPTION
plugins allow wic functionality to be extended and specialized by
users. This section documents the plugin interface, which is
currently restricted to 'source' plugins.
'Source' plugins provide a mechanism to customize various aspects
of the image generation process in wic, mainly the contents of
partitions.
Source plugins provide a mechanism for mapping values specified in
.wks files using the --source keyword to a particular plugin
implementation that populates a corresponding partition.
A source plugin is created as a subclass of SourcePlugin (see
scripts/lib/wic/pluginbase.py) and the plugin file containing it
is added to scripts/lib/wic/plugins/source/ to make the plugin
implementation available to the wic implementation.
Source plugins can also be implemented and added by external
layers - any plugins found in a scripts/lib/wic/plugins/source/
directory in an external layer will also be made available.
When the wic implementation needs to invoke a partition-specific
implementation, it looks for the plugin that has the same name as
the --source param given to that partition. For example, if the
partition is set up like this:
part /boot --source bootimg-pcbios ...
then the methods defined as class members of the plugin having the
matching bootimg-pcbios .name class member would be used.
To be more concrete, here's the plugin definition that would match
a '--source bootimg-pcbios' usage, along with an example method
that would be called by the wic implementation when it needed to
invoke an implementation-specific partition-preparation function:
class BootimgPcbiosPlugin(SourcePlugin):
name = 'bootimg-pcbios'
@classmethod
def do_prepare_partition(self, part, ...)
If the subclass itself doesn't implement a function, a 'default'
version in a superclass will be located and used, which is why all
plugins must be derived from SourcePlugin.
The SourcePlugin class defines the following methods, which is the
current set of methods that can be implemented/overridden by
--source plugins. Any methods not implemented by a SourcePlugin
subclass inherit the implementations present in the SourcePlugin
class (see the SourcePlugin source for details):
do_prepare_partition()
Called to do the actual content population for a
partition. In other words, it 'prepares' the final partition
image which will be incorporated into the disk image.
do_configure_partition()
Called before do_prepare_partition(), typically used to
create custom configuration files for a partition, for
example syslinux or grub config files.
do_install_disk()
Called after all partitions have been prepared and assembled
into a disk image. This provides a hook to allow
finalization of a disk image, for example to write an MBR to
it.
do_stage_partition()
Special content-staging hook called before
do_prepare_partition(), normally empty.
Typically, a partition will just use the passed-in
parameters, for example the unmodified value of bootimg_dir.
In some cases however, things may need to be more tailored.
As an example, certain files may additionally need to be
take from bootimg_dir + /boot. This hook allows those files
to be staged in a customized fashion. Note that
get_bitbake_var() allows you to access non-standard
variables that you might want to use for these types of
situations.
This scheme is extensible - adding more hooks is a simple matter
of adding more plugin methods to SourcePlugin and derived classes.
The code that then needs to call the plugin methods uses
plugin.get_source_plugin_methods() to find the method(s) needed by
the call; this is done by filling up a dict with keys containing
the method names of interest - on success, these will be filled in
with the actual methods. Please see the implementation for
examples and details.
"""
wic_overview_help = """
NAME
wic overview - General overview of wic
DESCRIPTION
The 'wic' command generates partitioned images from existing
OpenEmbedded build artifacts. Image generation is driven by
partitioning commands contained in an 'Openembedded kickstart'
(.wks) file (see 'wic help kickstart') specified either directly
on the command-line or as one of a selection of canned .wks files
(see 'wic list images'). When applied to a given set of build
artifacts, the result is an image or set of images that can be
directly written onto media and used on a particular system.
The 'wic' command and the infrastructure it's based on is by
definition incomplete - its purpose is to allow the generation of
customized images, and as such was designed to be completely
extensible via a plugin interface (see 'wic help plugins').
Background and Motivation
wic is meant to be a completely independent standalone utility
that initially provides easier-to-use and more flexible
replacements for a couple bits of existing functionality in
oe-core: directdisk.bbclass and mkefidisk.sh. The difference
between wic and those examples is that with wic the functionality
of those scripts is implemented by a general-purpose partitioning
'language' based on Redhat kickstart syntax).
The initial motivation and design considerations that lead to the
current tool are described exhaustively in Yocto Bug #3847
(https://bugzilla.yoctoproject.org/show_bug.cgi?id=3847).
Implementation and Examples
wic can be used in two different modes, depending on how much
control the user needs in specifying the Openembedded build
artifacts that will be used in creating the image: 'raw' and
'cooked'.
If used in 'raw' mode, artifacts are explicitly specified via
command-line arguments (see example below).
The more easily usable 'cooked' mode uses the current MACHINE
setting and a specified image name to automatically locate the
artifacts used to create the image.
OE kickstart files (.wks) can of course be specified directly on
the command-line, but the user can also choose from a set of
'canned' .wks files available via the 'wic list images' command
(example below).
In any case, the prerequisite for generating any image is to have
the build artifacts already available. The below examples assume
the user has already build a 'core-image-minimal' for a specific
machine (future versions won't require this redundant step, but
for now that's typically how build artifacts get generated).
The other prerequisite is to source the build environment:
$ source oe-init-build-env
To start out with, we'll generate an image from one of the canned
.wks files. The following generates a list of availailable
images:
$ wic list images
mkefidisk Create an EFI disk image
directdisk Create a 'pcbios' direct disk image
You can get more information about any of the available images by
typing 'wic list xxx help', where 'xxx' is one of the image names:
$ wic list mkefidisk help
Creates a partitioned EFI disk image that the user can directly dd
to boot media.
At any time, you can get help on the 'wic' command or any
subcommand (currently 'list' and 'create'). For instance, to get
the description of 'wic create' command and its parameters:
$ wic create
Usage:
Create a new OpenEmbedded image
usage: wic create <wks file or image name> [-o <DIRNAME> | ...]
[-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>]
[-e | --image-name] [-s, --skip-build-check] [-D, --debug]
[-r, --rootfs-dir] [-b, --bootimg-dir] [-k, --kernel-dir]
[-n, --native-sysroot] [-f, --build-rootfs]
This command creates an OpenEmbedded image based on the 'OE
kickstart commands' found in the <wks file>.
The -o option can be used to place the image in a directory
with a different name and location.
See 'wic help create' for more detailed instructions.
...
As mentioned in the command, you can get even more detailed
information by adding 'help' to the above:
$ wic help create
So, the easiest way to create an image is to use the -e option
with a canned .wks file. To use the -e option, you need to
specify the image used to generate the artifacts and you actually
need to have the MACHINE used to build them specified in your
local.conf (these requirements aren't necessary if you aren't
using the -e options.) Below, we generate a directdisk image,
pointing the process at the core-image-minimal artifacts for the
current MACHINE:
$ wic create directdisk -e core-image-minimal
Checking basic build environment...
Done.
Creating image(s)...
Info: The new image(s) can be found here:
/var/tmp/wic/build/directdisk-201309252350-sda.direct
The following build artifacts were used to create the image(s):
ROOTFS_DIR: ...
BOOTIMG_DIR: ...
KERNEL_DIR: ...
NATIVE_SYSROOT: ...
The image(s) were created using OE kickstart file:
.../scripts/lib/wic/canned-wks/directdisk.wks
The output shows the name and location of the image created, and
so that you know exactly what was used to generate the image, each
of the artifacts and the kickstart file used.
Similarly, you can create a 'mkefidisk' image in the same way
(notice that this example uses a different machine - because it's
using the -e option, you need to change the MACHINE in your
local.conf):
$ wic create mkefidisk -e core-image-minimal
Checking basic build environment...
Done.
Creating image(s)...
Info: The new image(s) can be found here:
/var/tmp/wic/build/mkefidisk-201309260027-sda.direct
...
Here's an example that doesn't take the easy way out and manually
specifies each build artifact, along with a non-canned .wks file,
and also uses the -o option to have wic create the output
somewhere other than the default /var/tmp/wic:
$ wic create ./test.wks -o ./out --rootfs-dir
tmp/work/qemux86_64-poky-linux/core-image-minimal/1.0-r0/rootfs
--bootimg-dir tmp/sysroots/qemux86-64/usr/share
--kernel-dir tmp/deploy/images/qemux86-64
--native-sysroot tmp/sysroots/x86_64-linux
Creating image(s)...
Info: The new image(s) can be found here:
out/build/test-201507211313-sda.direct
The following build artifacts were used to create the image(s):
ROOTFS_DIR: tmp/work/qemux86_64-poky-linux/core-image-minimal/1.0-r0/rootfs
BOOTIMG_DIR: tmp/sysroots/qemux86-64/usr/share
KERNEL_DIR: tmp/deploy/images/qemux86-64
NATIVE_SYSROOT: tmp/sysroots/x86_64-linux
The image(s) were created using OE kickstart file:
./test.wks
Here is a content of test.wks:
part /boot --source bootimg-pcbios --ondisk sda --label boot --active --align 1024
part / --source rootfs --ondisk sda --fstype=ext3 --label platform --align 1024
bootloader --timeout=0 --append="rootwait rootfstype=ext3 video=vesafb vga=0x318 console=tty0"
Finally, here's an example of the actual partition language
commands used to generate the mkefidisk image i.e. these are the
contents of the mkefidisk.wks OE kickstart file:
# short-description: Create an EFI disk image
# long-description: Creates a partitioned EFI disk image that the user
# can directly dd to boot media.
part /boot --source bootimg-efi --ondisk sda --fstype=efi --active
part / --source rootfs --ondisk sda --fstype=ext3 --label platform
part swap --ondisk sda --size 44 --label swap1 --fstype=swap
bootloader --timeout=10 --append="rootwait console=ttyPCH0,115200"
You can get a complete listing and description of all the
kickstart commands available for use in .wks files from 'wic help
kickstart'.
"""
wic_kickstart_help = """
NAME
wic kickstart - wic kickstart reference
DESCRIPTION
This section provides the definitive reference to the wic
kickstart language. It also provides documentation on the list of
--source plugins available for use from the 'part' command (see
the 'Platform-specific Plugins' section below).
The current wic implementation supports only the basic kickstart
partitioning commands: partition (or part for short) and
bootloader.
The following is a listing of the commands, their syntax, and
meanings. The commands are based on the Fedora kickstart
documentation but with modifications to reflect wic capabilities.
http://fedoraproject.org/wiki/Anaconda/Kickstart#part_or_partition
http://fedoraproject.org/wiki/Anaconda/Kickstart#bootloader
Commands
* 'part' or 'partition'
This command creates a partition on the system and uses the
following syntax:
part <mountpoint>
The <mountpoint> is where the partition will be mounted and
must take of one of the following forms:
/<path>: For example: /, /usr, or /home
swap: The partition will be used as swap space.
The following are supported 'part' options:
--size: The minimum partition size. Specify an integer value
such as 500. Multipliers k, M ang G can be used. If
not specified, the size is in MB.
You do not need this option if you use --source.
--source: This option is a wic-specific option that names the
source of the data that will populate the
partition. The most common value for this option
is 'rootfs', but can be any value which maps to a
valid 'source plugin' (see 'wic help plugins').
If '--source rootfs' is used, it tells the wic
command to create a partition as large as needed
and to fill it with the contents of the root
filesystem pointed to by the '-r' wic command-line
option (or the equivalent rootfs derived from the
'-e' command-line option). The filesystem type
that will be used to create the partition is driven
by the value of the --fstype option specified for
the partition (see --fstype below).
If --source <plugin-name>' is used, it tells the
wic command to create a partition as large as
needed and to fill with the contents of the
partition that will be generated by the specified
plugin name using the data pointed to by the '-r'
wic command-line option (or the equivalent rootfs
derived from the '-e' command-line option).
Exactly what those contents and filesystem type end
up being are dependent on the given plugin
implementation.
If --source option is not used, the wic command
will create empty partition. --size parameter has
to be used to specify size of empty partition.
--ondisk or --ondrive: Forces the partition to be created on
a particular disk.
--fstype: Sets the file system type for the partition. These
apply to partitions created using '--source rootfs' (see
--source above). Valid values are:
ext2
ext3
ext4
btrfs
squashfs
swap
--fsoptions: Specifies a free-form string of options to be
used when mounting the filesystem. This string
will be copied into the /etc/fstab file of the
installed system and should be enclosed in
quotes. If not specified, the default string is
"defaults".
--label label: Specifies the label to give to the filesystem
to be made on the partition. If the given
label is already in use by another filesystem,
a new label is created for the partition.
--active: Marks the partition as active.
--align (in KBytes): This option is specific to wic and says
to start a partition on an x KBytes
boundary.
--no-table: This option is specific to wic. Space will be
reserved for the partition and it will be
populated but it will not be added to the
partition table. It may be useful for
bootloaders.
--extra-space: This option is specific to wic. It adds extra
space after the space filled by the content
of the partition. The final size can go
beyond the size specified by --size.
By default, 10MB.
--overhead-factor: This option is specific to wic. The
size of the partition is multiplied by
this factor. It has to be greater than or
equal to 1.
The default value is 1.3.
--part-type: This option is specific to wic. It specifies partition
type GUID for GPT partitions.
List of partition type GUIDS can be found here:
http://en.wikipedia.org/wiki/GUID_Partition_Table#Partition_type_GUIDs
--use-uuid: This option is specific to wic. It makes wic to generate
random globally unique identifier (GUID) for the partition
and use it in bootloader configuration to specify root partition.
--uuid: This option is specific to wic. It specifies partition UUID.
It's useful if preconfigured partition UUID is added to kernel command line
in bootloader configuration before running wic. In this case .wks file can
be generated or modified to set preconfigured parition UUID using this option.
* bootloader
This command allows the user to specify various bootloader
options. The following are supported 'bootloader' options:
--timeout: Specifies the number of seconds before the
bootloader times out and boots the default option.
--append: Specifies kernel parameters. These will be added to
bootloader command-line - for example, the syslinux
APPEND or grub kernel command line.
Note that bootloader functionality and boot partitions are
implemented by the various --source plugins that implement
bootloader functionality; the bootloader command essentially
provides a means of modifying bootloader configuration.
"""