To use QEMU, you need to have QEMU installed and initialized as well as have the proper artifacts (i.e. image files and root filesystems) available. Follow these general steps to run QEMU:
Install QEMU: QEMU is made available with the Yocto Project a number of ways. One method is to install a Software Development Kit (SDK). See "The QEMU Emulator" section in the Yocto Project Application Development and the Extensible Software Development Kit (eSDK) manual for information on how to install QEMU.
Setting Up the Environment: How you set up the QEMU environment depends on how you installed QEMU:
If you cloned the poky
repository or you downloaded and unpacked a
Yocto Project release tarball, you can source
the build environment script (i.e.
oe-init-build-env
):
$ cd ~/poky $ source oe-init-build-env
If you installed a cross-toolchain, you can
run the script that initializes the toolchain.
For example, the following commands run the
initialization script from the default
poky_sdk
directory:
. ~/poky_sdk/environment-setup-core2-64-poky-linux
Ensure the Artifacts are in Place: You need to be sure you have a pre-built kernel that will boot in QEMU. You also need the target root filesystem for your target machine’s architecture:
If you have previously built an image for QEMU
(e.g. qemux86
,
qemuarm
, and so forth),
then the artifacts are in place in your
Build Directory.
If you have not built an image, you can go to the machines/qemu area and download a pre-built image that matches your architecture and can be run on QEMU.
See the "Extracting the Root Filesystem" section in the Yocto Project Application Development and the Extensible Software Development Kit (eSDK) manual for information on how to extract a root filesystem.
Run QEMU:
The basic runqemu
command syntax is as
follows:
$ runqemu [option
] [...]
Based on what you provide on the command line,
runqemu
does a good job of figuring
out what you are trying to do.
For example, by default, QEMU looks for the most recently
built image according to the timestamp when it needs to
look for an image.
Minimally, through the use of options, you must provide
either a machine name, a virtual machine image
(*wic.vmdk
), or a kernel image
(*.bin
).
Here are some additional examples to help illustrate further QEMU:
This example starts QEMU with
MACHINE
set to "qemux86".
Assuming a standard
Build Directory,
runqemu
automatically finds the
bzImage-qemux86.bin
image file and
the
core-image-minimal-qemux86-20140707074611.rootfs.ext3
(assuming the current build created a
core-image-minimal
image).
$ runqemu qemux86
This example produces the exact same results as the previous example. This command, however, specifically provides the image and root filesystem type.
$ runqemu qemux86 core-image-minimal ext3
This example specifies to boot an initial RAM disk image
and to enable audio in QEMU.
For this case, runqemu
set the
internal variable FSTYPE
to
"cpio.gz".
Also, for audio to be enabled, an appropriate driver must
be installed (see the previous description for the
audio
option for more information).
$ runqemu qemux86 ramfs audio
This example does not provide enough information for
QEMU to launch.
While the command does provide a root filesystem type, it
must also minimally provide a
MACHINE
,
KERNEL
, or
VM
option.
$ runqemu ext3
This example specifies to boot a virtual machine
image (.wic.vmdk
file).
From the .wic.vmdk
,
runqemu
determines the QEMU
architecture (MACHINE
) to be
"qemux86" and the root filesystem type to be "vmdk".
$ runqemu /home/scott-lenovo/vm/core-image-minimal-qemux86.wic.vmdk