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1.. SPDX-License-Identifier: CC-BY-SA-2.0-UK
2
3Creating Partitioned Images Using Wic
4*************************************
5
6Creating an image for a particular hardware target using the
7OpenEmbedded build system does not necessarily mean you can boot that
8image as is on your device. Physical devices accept and boot images in
9various ways depending on the specifics of the device. Usually,
10information about the hardware can tell you what image format the device
11requires. Should your device require multiple partitions on an SD card,
12flash, or an HDD, you can use the OpenEmbedded Image Creator, Wic, to
13create the properly partitioned image.
14
15The ``wic`` command generates partitioned images from existing
16OpenEmbedded build artifacts. Image generation is driven by partitioning
17commands contained in an OpenEmbedded kickstart file (``.wks``)
18specified either directly on the command line or as one of a selection
19of canned kickstart files as shown with the ``wic list images`` command
20in the
21":ref:`dev-manual/wic:generate an image using an existing kickstart file`"
22section. When you apply the command to a given set of build artifacts, the
23result is an image or set of images that can be directly written onto media and
24used on a particular system.
25
26.. note::
27
28 For a kickstart file reference, see the
29 ":ref:`ref-manual/kickstart:openembedded kickstart (\`\`.wks\`\`) reference`"
30 Chapter in the Yocto Project Reference Manual.
31
32The ``wic`` command and the infrastructure it is based on is by
33definition incomplete. The purpose of the command is to allow the
34generation of customized images, and as such, was designed to be
35completely extensible through a plugin interface. See the
36":ref:`dev-manual/wic:using the wic plugin interface`" section
37for information on these plugins.
38
39This section provides some background information on Wic, describes what
40you need to have in place to run the tool, provides instruction on how
41to use the Wic utility, provides information on using the Wic plugins
42interface, and provides several examples that show how to use Wic.
43
44Background
45==========
46
47This section provides some background on the Wic utility. While none of
48this information is required to use Wic, you might find it interesting.
49
50- The name "Wic" is derived from OpenEmbedded Image Creator (oeic). The
51 "oe" diphthong in "oeic" was promoted to the letter "w", because
52 "oeic" is both difficult to remember and to pronounce.
53
54- Wic is loosely based on the Meego Image Creator (``mic``) framework.
55 The Wic implementation has been heavily modified to make direct use
56 of OpenEmbedded build artifacts instead of package installation and
57 configuration, which are already incorporated within the OpenEmbedded
58 artifacts.
59
60- Wic is a completely independent standalone utility that initially
61 provides easier-to-use and more flexible replacements for an existing
62 functionality in OE-Core's :ref:`ref-classes-image-live`
63 class. The difference between Wic and those examples is that with Wic
64 the functionality of those scripts is implemented by a
65 general-purpose partitioning language, which is based on Redhat
66 kickstart syntax.
67
68Requirements
69============
70
71In order to use the Wic utility with the OpenEmbedded Build system, your
72system needs to meet the following requirements:
73
74- The Linux distribution on your development host must support the
75 Yocto Project. See the ":ref:`system-requirements-supported-distros`"
76 section in the Yocto Project Reference Manual for the list of
77 distributions that support the Yocto Project.
78
79- The standard system utilities, such as ``cp``, must be installed on
80 your development host system.
81
82- You must have sourced the build environment setup script (i.e.
83 :ref:`structure-core-script`) found in the :term:`Build Directory`.
84
85- You need to have the build artifacts already available, which
86 typically means that you must have already created an image using the
87 OpenEmbedded build system (e.g. ``core-image-minimal``). While it
88 might seem redundant to generate an image in order to create an image
89 using Wic, the current version of Wic requires the artifacts in the
90 form generated by the OpenEmbedded build system.
91
92- You must build several native tools, which are built to run on the
93 build system::
94
95 $ bitbake wic-tools
96
97- Include "wic" as part of the
98 :term:`IMAGE_FSTYPES`
99 variable.
100
101- Include the name of the :ref:`wic kickstart file <openembedded-kickstart-wks-reference>`
102 as part of the :term:`WKS_FILE` variable. If multiple candidate files can
103 be provided by different layers, specify all the possible names through the
104 :term:`WKS_FILES` variable instead.
105
106Getting Help
107============
108
109You can get general help for the ``wic`` command by entering the ``wic``
110command by itself or by entering the command with a help argument as
111follows::
112
113 $ wic -h
114 $ wic --help
115 $ wic help
116
117Currently, Wic supports seven commands: ``cp``, ``create``, ``help``,
118``list``, ``ls``, ``rm``, and ``write``. You can get help for all these
119commands except "help" by using the following form::
120
121 $ wic help command
122
123For example, the following command returns help for the ``write``
124command::
125
126 $ wic help write
127
128Wic supports help for three topics: ``overview``, ``plugins``, and
129``kickstart``. You can get help for any topic using the following form::
130
131 $ wic help topic
132
133For example, the following returns overview help for Wic::
134
135 $ wic help overview
136
137There is one additional level of help for Wic. You can get help on
138individual images through the ``list`` command. You can use the ``list``
139command to return the available Wic images as follows::
140
141 $ wic list images
142 genericx86 Create an EFI disk image for genericx86*
143 beaglebone-yocto Create SD card image for Beaglebone
144 qemuriscv Create qcow2 image for RISC-V QEMU machines
145 mkefidisk Create an EFI disk image
146 qemuloongarch Create qcow2 image for LoongArch QEMU machines
147 directdisk-multi-rootfs Create multi rootfs image using rootfs plugin
148 directdisk Create a 'pcbios' direct disk image
149 efi-bootdisk
150 mkhybridiso Create a hybrid ISO image
151 directdisk-gpt Create a 'pcbios' direct disk image
152 systemd-bootdisk Create an EFI disk image with systemd-boot
153 sdimage-bootpart Create SD card image with a boot partition
154 qemux86-directdisk Create a qemu machine 'pcbios' direct disk image
155 directdisk-bootloader-config Create a 'pcbios' direct disk image with custom bootloader config
156
157Once you know the list of available
158Wic images, you can use ``help`` with the command to get help on a
159particular image. For example, the following command returns help on the
160"beaglebone-yocto" image::
161
162 $ wic list beaglebone-yocto help
163
164 Creates a partitioned SD card image for Beaglebone.
165 Boot files are located in the first vfat partition.
166
167Operational Modes
168=================
169
170You can use Wic in two different modes, depending on how much control
171you need for specifying the OpenEmbedded build artifacts that are used
172for creating the image: Raw and Cooked:
173
174- *Raw Mode:* You explicitly specify build artifacts through Wic
175 command-line arguments.
176
177- *Cooked Mode:* The current
178 :term:`MACHINE` setting and image
179 name are used to automatically locate and provide the build
180 artifacts. You just supply a kickstart file and the name of the image
181 from which to use artifacts.
182
183Regardless of the mode you use, you need to have the build artifacts
184ready and available.
185
186Raw Mode
187--------
188
189Running Wic in raw mode allows you to specify all the partitions through
190the ``wic`` command line. The primary use for raw mode is if you have
191built your kernel outside of the Yocto Project :term:`Build Directory`.
192In other words, you can point to arbitrary kernel, root filesystem locations,
193and so forth. Contrast this behavior with cooked mode where Wic looks in the
194:term:`Build Directory` (e.g. ``tmp/deploy/images/``\ machine).
195
196The general form of the ``wic`` command in raw mode is::
197
198 $ wic create wks_file options ...
199
200 Where:
201
202 wks_file:
203 An OpenEmbedded kickstart file. You can provide
204 your own custom file or use a file from a set of
205 existing files as described by further options.
206
207 optional arguments:
208 -h, --help show this help message and exit
209 -o OUTDIR, --outdir OUTDIR
210 name of directory to create image in
211 -e IMAGE_NAME, --image-name IMAGE_NAME
212 name of the image to use the artifacts from e.g. core-
213 image-sato
214 -r ROOTFS_DIR, --rootfs-dir ROOTFS_DIR
215 path to the /rootfs dir to use as the .wks rootfs
216 source
217 -b BOOTIMG_DIR, --bootimg-dir BOOTIMG_DIR
218 path to the dir containing the boot artifacts (e.g.
219 /EFI or /syslinux dirs) to use as the .wks bootimg
220 source
221 -k KERNEL_DIR, --kernel-dir KERNEL_DIR
222 path to the dir containing the kernel to use in the
223 .wks bootimg
224 -n NATIVE_SYSROOT, --native-sysroot NATIVE_SYSROOT
225 path to the native sysroot containing the tools to use
226 to build the image
227 -s, --skip-build-check
228 skip the build check
229 -f, --build-rootfs build rootfs
230 -c {gzip,bzip2,xz}, --compress-with {gzip,bzip2,xz}
231 compress image with specified compressor
232 -m, --bmap generate .bmap
233 --no-fstab-update Do not change fstab file.
234 -v VARS_DIR, --vars VARS_DIR
235 directory with <image>.env files that store bitbake
236 variables
237 -D, --debug output debug information
238
239.. note::
240
241 You do not need root privileges to run Wic. In fact, you should not
242 run as root when using the utility.
243
244Cooked Mode
245-----------
246
247Running Wic in cooked mode leverages off artifacts in the
248:term:`Build Directory`. In other words, you do not have to specify kernel or
249root filesystem locations as part of the command. All you need to provide is
250a kickstart file and the name of the image from which to use artifacts
251by using the "-e" option. Wic looks in the :term:`Build Directory` (e.g.
252``tmp/deploy/images/``\ machine) for artifacts.
253
254The general form of the ``wic`` command using Cooked Mode is as follows::
255
256 $ wic create wks_file -e IMAGE_NAME
257
258 Where:
259
260 wks_file:
261 An OpenEmbedded kickstart file. You can provide
262 your own custom file or use a file from a set of
263 existing files provided with the Yocto Project
264 release.
265
266 required argument:
267 -e IMAGE_NAME, --image-name IMAGE_NAME
268 name of the image to use the artifacts from e.g. core-
269 image-sato
270
271Using an Existing Kickstart File
272================================
273
274If you do not want to create your own kickstart file, you can use an
275existing file provided by the Wic installation. As shipped, kickstart
276files can be found in the :ref:`overview-manual/development-environment:yocto project source repositories` in the
277following two locations::
278
279 poky/meta-yocto-bsp/wic
280 poky/scripts/lib/wic/canned-wks
281
282Use the following command to list the available kickstart files::
283
284 $ wic list images
285 genericx86 Create an EFI disk image for genericx86*
286 beaglebone-yocto Create SD card image for Beaglebone
287 qemuriscv Create qcow2 image for RISC-V QEMU machines
288 mkefidisk Create an EFI disk image
289 qemuloongarch Create qcow2 image for LoongArch QEMU machines
290 directdisk-multi-rootfs Create multi rootfs image using rootfs plugin
291 directdisk Create a 'pcbios' direct disk image
292 efi-bootdisk
293 mkhybridiso Create a hybrid ISO image
294 directdisk-gpt Create a 'pcbios' direct disk image
295 systemd-bootdisk Create an EFI disk image with systemd-boot
296 sdimage-bootpart Create SD card image with a boot partition
297 qemux86-directdisk Create a qemu machine 'pcbios' direct disk image
298 directdisk-bootloader-config Create a 'pcbios' direct disk image with custom bootloader config
299
300When you use an existing file, you
301do not have to use the ``.wks`` extension. Here is an example in Raw
302Mode that uses the ``directdisk`` file::
303
304 $ wic create directdisk -r rootfs_dir -b bootimg_dir \
305 -k kernel_dir -n native_sysroot
306
307Here are the actual partition language commands used in the
308``genericx86.wks`` file to generate an image::
309
310 # short-description: Create an EFI disk image for genericx86*
311 # long-description: Creates a partitioned EFI disk image for genericx86* machines
312 part /boot --source bootimg-efi --sourceparams="loader=grub-efi" --ondisk sda --label msdos --active --align 1024
313 part / --source rootfs --ondisk sda --fstype=ext4 --label platform --align 1024 --use-uuid
314 part swap --ondisk sda --size 44 --label swap1 --fstype=swap
315
316 bootloader --ptable gpt --timeout=5 --append="rootfstype=ext4 console=ttyS0,115200 console=tty0"
317
318Using the Wic Plugin Interface
319==============================
320
321You can extend and specialize Wic functionality by using Wic plugins.
322This section explains the Wic plugin interface.
323
324.. note::
325
326 Wic plugins consist of "source" and "imager" plugins. Imager plugins
327 are beyond the scope of this section.
328
329Source plugins provide a mechanism to customize partition content during
330the Wic image generation process. You can use source plugins to map
331values that you specify using ``--source`` commands in kickstart files
332(i.e. ``*.wks``) to a plugin implementation used to populate a given
333partition.
334
335.. note::
336
337 If you use plugins that have build-time dependencies (e.g. native
338 tools, bootloaders, and so forth) when building a Wic image, you need
339 to specify those dependencies using the :term:`WKS_FILE_DEPENDS`
340 variable.
341
342Source plugins are subclasses defined in plugin files. As shipped, the
343Yocto Project provides several plugin files. You can see the source
344plugin files that ship with the Yocto Project
345:yocto_git:`here </poky/tree/scripts/lib/wic/plugins/source>`.
346Each of these plugin files contains source plugins that are designed to
347populate a specific Wic image partition.
348
349Source plugins are subclasses of the ``SourcePlugin`` class, which is
350defined in the ``poky/scripts/lib/wic/pluginbase.py`` file. For example,
351the ``BootimgEFIPlugin`` source plugin found in the ``bootimg-efi.py``
352file is a subclass of the ``SourcePlugin`` class, which is found in the
353``pluginbase.py`` file.
354
355You can also implement source plugins in a layer outside of the Source
356Repositories (external layer). To do so, be sure that your plugin files
357are located in a directory whose path is
358``scripts/lib/wic/plugins/source/`` within your external layer. When the
359plugin files are located there, the source plugins they contain are made
360available to Wic.
361
362When the Wic implementation needs to invoke a partition-specific
363implementation, it looks for the plugin with the same name as the
364``--source`` parameter used in the kickstart file given to that
365partition. For example, if the partition is set up using the following
366command in a kickstart file::
367
368 part /boot --source bootimg-pcbios --ondisk sda --label boot --active --align 1024
369
370The methods defined as class
371members of the matching source plugin (i.e. ``bootimg-pcbios``) in the
372``bootimg-pcbios.py`` plugin file are used.
373
374To be more concrete, here is the corresponding plugin definition from
375the ``bootimg-pcbios.py`` file for the previous command along with an
376example method called by the Wic implementation when it needs to prepare
377a partition using an implementation-specific function::
378
379 .
380 .
381 .
382 class BootimgPcbiosPlugin(SourcePlugin):
383 """
384 Create MBR boot partition and install syslinux on it.
385 """
386
387 name = 'bootimg-pcbios'
388 .
389 .
390 .
391 @classmethod
392 def do_prepare_partition(cls, part, source_params, creator, cr_workdir,
393 oe_builddir, bootimg_dir, kernel_dir,
394 rootfs_dir, native_sysroot):
395 """
396 Called to do the actual content population for a partition i.e. it
397 'prepares' the partition to be incorporated into the image.
398 In this case, prepare content for legacy bios boot partition.
399 """
400 .
401 .
402 .
403
404If a
405subclass (plugin) itself does not implement a particular function, Wic
406locates and uses the default version in the superclass. It is for this
407reason that all source plugins are derived from the ``SourcePlugin``
408class.
409
410The ``SourcePlugin`` class defined in the ``pluginbase.py`` file defines
411a set of methods that source plugins can implement or override. Any
412plugins (subclass of ``SourcePlugin``) that do not implement a
413particular method inherit the implementation of the method from the
414``SourcePlugin`` class. For more information, see the ``SourcePlugin``
415class in the ``pluginbase.py`` file for details:
416
417The following list describes the methods implemented in the
418``SourcePlugin`` class:
419
420- ``do_prepare_partition()``: Called to populate a partition with
421 actual content. In other words, the method prepares the final
422 partition image that is incorporated into the disk image.
423
424- ``do_configure_partition()``: Called before
425 ``do_prepare_partition()`` to create custom configuration files for a
426 partition (e.g. syslinux or grub configuration files).
427
428- ``do_install_disk()``: Called after all partitions have been
429 prepared and assembled into a disk image. This method provides a hook
430 to allow finalization of a disk image (e.g. writing an MBR).
431
432- ``do_stage_partition()``: Special content-staging hook called
433 before ``do_prepare_partition()``. This method is normally empty.
434
435 Typically, a partition just uses the passed-in parameters (e.g. the
436 unmodified value of ``bootimg_dir``). However, in some cases, things
437 might need to be more tailored. As an example, certain files might
438 additionally need to be taken from ``bootimg_dir + /boot``. This hook
439 allows those files to be staged in a customized fashion.
440
441 .. note::
442
443 ``get_bitbake_var()`` allows you to access non-standard variables that
444 you might want to use for this behavior.
445
446You can extend the source plugin mechanism. To add more hooks, create
447more source plugin methods within ``SourcePlugin`` and the corresponding
448derived subclasses. The code that calls the plugin methods uses the
449``plugin.get_source_plugin_methods()`` function to find the method or
450methods needed by the call. Retrieval of those methods is accomplished
451by filling up a dict with keys that contain the method names of
452interest. On success, these will be filled in with the actual methods.
453See the Wic implementation for examples and details.
454
455Wic Examples
456============
457
458This section provides several examples that show how to use the Wic
459utility. All the examples assume the list of requirements in the
460":ref:`dev-manual/wic:requirements`" section have been met. The
461examples assume the previously generated image is
462``core-image-minimal``.
463
464Generate an Image using an Existing Kickstart File
465--------------------------------------------------
466
467This example runs in Cooked Mode and uses the ``mkefidisk`` kickstart
468file::
469
470 $ wic create mkefidisk -e core-image-minimal
471 INFO: Building wic-tools...
472 .
473 .
474 .
475 INFO: The new image(s) can be found here:
476 ./mkefidisk-201804191017-sda.direct
477
478 The following build artifacts were used to create the image(s):
479 ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs
480 BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share
481 KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86
482 NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native
483
484 INFO: The image(s) were created using OE kickstart file:
485 /home/stephano/yocto/openembedded-core/scripts/lib/wic/canned-wks/mkefidisk.wks
486
487The previous example shows the easiest way to create an image by running
488in cooked mode and supplying a kickstart file and the "-e" option to
489point to the existing build artifacts. Your ``local.conf`` file needs to
490have the :term:`MACHINE` variable set
491to the machine you are using, which is "qemux86" in this example.
492
493Once the image builds, the output provides image location, artifact use,
494and kickstart file information.
495
496.. note::
497
498 You should always verify the details provided in the output to make
499 sure that the image was indeed created exactly as expected.
500
501Continuing with the example, you can now write the image from the
502:term:`Build Directory` onto a USB stick, or whatever media for which you
503built your image, and boot from the media. You can write the image by using
504``bmaptool`` or ``dd``::
505
506 $ oe-run-native bmaptool-native bmaptool copy mkefidisk-201804191017-sda.direct /dev/sdX
507
508or ::
509
510 $ sudo dd if=mkefidisk-201804191017-sda.direct of=/dev/sdX
511
512.. note::
513
514 For more information on how to use the ``bmaptool``
515 to flash a device with an image, see the
516 ":ref:`dev-manual/bmaptool:flashing images using \`\`bmaptool\`\``"
517 section.
518
519Using a Modified Kickstart File
520-------------------------------
521
522Because partitioned image creation is driven by the kickstart file, it
523is easy to affect image creation by changing the parameters in the file.
524This next example demonstrates that through modification of the
525``directdisk-gpt`` kickstart file.
526
527As mentioned earlier, you can use the command ``wic list images`` to
528show the list of existing kickstart files. The directory in which the
529``directdisk-gpt.wks`` file resides is
530``scripts/lib/image/canned-wks/``, which is located in the
531:term:`Source Directory` (e.g. ``poky``).
532Because available files reside in this directory, you can create and add
533your own custom files to the directory. Subsequent use of the
534``wic list images`` command would then include your kickstart files.
535
536In this example, the existing ``directdisk-gpt`` file already does most
537of what is needed. However, for the hardware in this example, the image
538will need to boot from ``sdb`` instead of ``sda``, which is what the
539``directdisk-gpt`` kickstart file uses.
540
541The example begins by making a copy of the ``directdisk-gpt.wks`` file
542in the ``scripts/lib/image/canned-wks`` directory and then by changing
543the lines that specify the target disk from which to boot::
544
545 $ cp /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisk-gpt.wks \
546 /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisksdb-gpt.wks
547
548Next, the example modifies the ``directdisksdb-gpt.wks`` file and
549changes all instances of "``--ondisk sda``" to "``--ondisk sdb``". The
550example changes the following two lines and leaves the remaining lines
551untouched::
552
553 part /boot --source bootimg-pcbios --ondisk sdb --label boot --active --align 1024
554 part / --source rootfs --ondisk sdb --fstype=ext4 --label platform --align 1024 --use-uuid
555
556Once the lines are changed, the
557example generates the ``directdisksdb-gpt`` image. The command points
558the process at the ``core-image-minimal`` artifacts for the Next Unit of
559Computing (nuc) :term:`MACHINE` the
560``local.conf``::
561
562 $ wic create directdisksdb-gpt -e core-image-minimal
563 INFO: Building wic-tools...
564 .
565 .
566 .
567 Initialising tasks: 100% |#######################################| Time: 0:00:01
568 NOTE: Executing SetScene Tasks
569 NOTE: Executing RunQueue Tasks
570 NOTE: Tasks Summary: Attempted 1161 tasks of which 1157 didn't need to be rerun and all succeeded.
571 INFO: Creating image(s)...
572
573 INFO: The new image(s) can be found here:
574 ./directdisksdb-gpt-201710090938-sdb.direct
575
576 The following build artifacts were used to create the image(s):
577 ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs
578 BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share
579 KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86
580 NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native
581
582 INFO: The image(s) were created using OE kickstart file:
583 /home/stephano/yocto/poky/scripts/lib/wic/canned-wks/directdisksdb-gpt.wks
584
585Continuing with the example, you can now directly ``dd`` the image to a
586USB stick, or whatever media for which you built your image, and boot
587the resulting media::
588
589 $ sudo dd if=directdisksdb-gpt-201710090938-sdb.direct of=/dev/sdb
590 140966+0 records in
591 140966+0 records out
592 72174592 bytes (72 MB, 69 MiB) copied, 78.0282 s, 925 kB/s
593 $ sudo eject /dev/sdb
594
595Using a Modified Kickstart File and Running in Raw Mode
596-------------------------------------------------------
597
598This next example manually specifies each build artifact (runs in Raw
599Mode) and uses a modified kickstart file. The example also uses the
600``-o`` option to cause Wic to create the output somewhere other than the
601default output directory, which is the current directory::
602
603 $ wic create test.wks -o /home/stephano/testwic \
604 --rootfs-dir /home/stephano/yocto/build/tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/rootfs \
605 --bootimg-dir /home/stephano/yocto/build/tmp/work/qemux86-poky-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share \
606 --kernel-dir /home/stephano/yocto/build/tmp/deploy/images/qemux86 \
607 --native-sysroot /home/stephano/yocto/build/tmp/work/i586-poky-linux/wic-tools/1.0-r0/recipe-sysroot-native
608
609 INFO: Creating image(s)...
610
611 INFO: The new image(s) can be found here:
612 /home/stephano/testwic/test-201710091445-sdb.direct
613
614 The following build artifacts were used to create the image(s):
615 ROOTFS_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/rootfs
616 BOOTIMG_DIR: /home/stephano/yocto/build/tmp-glibc/work/qemux86-oe-linux/core-image-minimal/1.0-r0/recipe-sysroot/usr/share
617 KERNEL_DIR: /home/stephano/yocto/build/tmp-glibc/deploy/images/qemux86
618 NATIVE_SYSROOT: /home/stephano/yocto/build/tmp-glibc/work/i586-oe-linux/wic-tools/1.0-r0/recipe-sysroot-native
619
620 INFO: The image(s) were created using OE kickstart file:
621 test.wks
622
623For this example,
624:term:`MACHINE` did not have to be
625specified in the ``local.conf`` file since the artifact is manually
626specified.
627
628Using Wic to Manipulate an Image
629--------------------------------
630
631Wic image manipulation allows you to shorten turnaround time during
632image development. For example, you can use Wic to delete the kernel
633partition of a Wic image and then insert a newly built kernel. This
634saves you time from having to rebuild the entire image each time you
635modify the kernel.
636
637.. note::
638
639 In order to use Wic to manipulate a Wic image as in this example,
640 your development machine must have the ``mtools`` package installed.
641
642The following example examines the contents of the Wic image, deletes
643the existing kernel, and then inserts a new kernel:
644
645#. *List the Partitions:* Use the ``wic ls`` command to list all the
646 partitions in the Wic image::
647
648 $ wic ls tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic
649 Num Start End Size Fstype
650 1 1048576 25041919 23993344 fat16
651 2 25165824 72157183 46991360 ext4
652
653 The previous output shows two partitions in the
654 ``core-image-minimal-qemux86.wic`` image.
655
656#. *Examine a Particular Partition:* Use the ``wic ls`` command again
657 but in a different form to examine a particular partition.
658
659 .. note::
660
661 You can get command usage on any Wic command using the following
662 form::
663
664 $ wic help command
665
666
667 For example, the following command shows you the various ways to
668 use the
669 wic ls
670 command::
671
672 $ wic help ls
673
674
675 The following command shows what is in partition one::
676
677 $ wic ls tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1
678 Volume in drive : is boot
679 Volume Serial Number is E894-1809
680 Directory for ::/
681
682 libcom32 c32 186500 2017-10-09 16:06
683 libutil c32 24148 2017-10-09 16:06
684 syslinux cfg 220 2017-10-09 16:06
685 vesamenu c32 27104 2017-10-09 16:06
686 vmlinuz 6904608 2017-10-09 16:06
687 5 files 7 142 580 bytes
688 16 582 656 bytes free
689
690 The previous output shows five files, with the
691 ``vmlinuz`` being the kernel.
692
693 .. note::
694
695 If you see the following error, you need to update or create a
696 ``~/.mtoolsrc`` file and be sure to have the line "mtools_skip_check=1"
697 in the file. Then, run the Wic command again::
698
699 ERROR: _exec_cmd: /usr/bin/mdir -i /tmp/wic-parttfokuwra ::/ returned '1' instead of 0
700 output: Total number of sectors (47824) not a multiple of sectors per track (32)!
701 Add mtools_skip_check=1 to your .mtoolsrc file to skip this test
702
703
704#. *Remove the Old Kernel:* Use the ``wic rm`` command to remove the
705 ``vmlinuz`` file (kernel)::
706
707 $ wic rm tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1/vmlinuz
708
709#. *Add In the New Kernel:* Use the ``wic cp`` command to add the
710 updated kernel to the Wic image. Depending on how you built your
711 kernel, it could be in different places. If you used ``devtool`` and
712 an SDK to build your kernel, it resides in the ``tmp/work`` directory
713 of the extensible SDK. If you used ``make`` to build the kernel, the
714 kernel will be in the ``workspace/sources`` area.
715
716 The following example assumes ``devtool`` was used to build the
717 kernel::
718
719 $ wic cp poky_sdk/tmp/work/qemux86-poky-linux/linux-yocto/4.12.12+git999-r0/linux-yocto-4.12.12+git999/arch/x86/boot/bzImage \
720 poky/build/tmp/deploy/images/qemux86/core-image-minimal-qemux86.wic:1/vmlinuz
721
722 Once the new kernel is added back into the image, you can use the
723 ``dd`` command or :ref:`bmaptool
724 <dev-manual/bmaptool:flashing images using \`\`bmaptool\`\`>`
725 to flash your wic image onto an SD card or USB stick and test your
726 target.
727
728 .. note::
729
730 Using ``bmaptool`` is generally 10 to 20 times faster than using ``dd``.
731