The images produced by the build system are compressed forms of the root filesystem and are ready to boot on a target device. You can see from the general workflow figure that BitBake output, in part, consists of images. This section takes a closer look at this output:
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The build process writes images out to the
Build Directory
inside the
tmp/deploy/images/
folder as shown in the figure.
This folder contains any files expected to be loaded on the
target device.
The
machine
/DEPLOY_DIR
variable points to the deploy
directory,
while the
DEPLOY_DIR_IMAGE
variable points to the appropriate directory containing images
for the current configuration.
kernel-image
:
A kernel binary file.
The
KERNEL_IMAGETYPE
variable determines the naming scheme for the
kernel image file.
Depending on this variable, the file could begin with
a variety of naming strings.
The
deploy/images/
machine
directory can contain multiple image files for the
machine.
root-filesystem-image
:
Root filesystems for the target device (e.g.
*.ext3
or
*.bz2
files).
The
IMAGE_FSTYPES
variable determines the root filesystem image type.
The
deploy/images/
machine
directory can contain multiple root filesystems for the
machine.
kernel-modules
:
Tarballs that contain all the modules built for the
kernel.
Kernel module tarballs exist for legacy purposes and
can be suppressed by setting the
MODULE_TARBALL_DEPLOY
variable to "0".
The
deploy/images/
machine
directory can contain multiple kernel module tarballs
for the machine.
bootloaders
:
If applicable to the target machine, bootloaders
supporting the image.
The deploy/images/
machine
directory can contain multiple bootloaders for the
machine.
symlinks
:
The
deploy/images/
machine
folder contains a symbolic link that points to the
most recently built file for each machine.
These links might be useful for external scripts that
need to obtain the latest version of each file.