mirror of
https://github.com/gnif/LookingGlass.git
synced 2024-11-24 14:27:20 +00:00
74444f8eed
Co-authored-by: Guanzhong Chen <quantum2048@gmail.com> Co-authored-by: Netboy3 <1472804+netboy3@users.noreply.github.com>
256 lines
6.3 KiB
ReStructuredText
256 lines
6.3 KiB
ReStructuredText
.. _kernel_module:
|
|
|
|
Kernel Module
|
|
#############
|
|
|
|
This kernel module implements a basic interface to the IVSHMEM device
|
|
for Looking Glass in VM->VM mode.
|
|
|
|
Additionally in VM->host mode, it can be used to generate a shared
|
|
memory device on the host machine that supports dmabuf.
|
|
|
|
Prerequisites
|
|
-------------
|
|
|
|
The linux kernel headers for your kernel version are required for building.
|
|
Install them with ``apt-get``
|
|
|
|
.. code:: bash
|
|
|
|
apt-get install linux-headers-$(uname -r)
|
|
|
|
Then switch to the ``module/`` directory
|
|
|
|
.. code:: bash
|
|
|
|
cd module/
|
|
|
|
.. _module_dkms:
|
|
|
|
Using DKMS (Recommended)
|
|
------------------------
|
|
|
|
You can use the kernel's DKMS feature to keep the module across upgrades.
|
|
``dkms`` must be installed.
|
|
|
|
.. code:: bash
|
|
|
|
apt-get install dkms
|
|
|
|
.. _module_dkms_install:
|
|
|
|
Installing
|
|
~~~~~~~~~~
|
|
|
|
To install the module into DKMS, run
|
|
|
|
.. code:: bash
|
|
|
|
dkms install "."
|
|
|
|
.. _module_dkms_loading:
|
|
|
|
Loading
|
|
~~~~~~~
|
|
|
|
For VM->VM, simply modprobe the module::
|
|
|
|
modprobe kvmfr
|
|
|
|
For VM->host with dmabuf, modprobe with the parameter
|
|
``static_size_mb``:
|
|
|
|
.. code:: bash
|
|
|
|
modprobe kvmfr static_size_mb=32
|
|
|
|
Just like above, multiple devices can be created by separating the sizes
|
|
with commas.
|
|
|
|
|
|
.. _module_manual:
|
|
|
|
Compiling & Loading (Manual)
|
|
----------------------------
|
|
|
|
To compile the module manually, run ``make`` in the module directory.
|
|
|
|
.. _module_manual_loading:
|
|
|
|
Loading
|
|
~~~~~~~
|
|
|
|
For VM->VM mode, run:
|
|
|
|
.. code:: bash
|
|
|
|
insmod kvmfr.ko
|
|
|
|
For VM->host mode with dmabuf, instead of creating a shared memory file,
|
|
load this module with the parameter ``static_size_mb``. For example, a
|
|
32 MB shared memory device can be created with:
|
|
|
|
.. code:: bash
|
|
|
|
insmod kvmfr.ko static_size_mb=32
|
|
|
|
Multiple devices can be created by separating the sizes with commas. For
|
|
example, ``static_size_mb=128,64`` would create two kvmfr devices:
|
|
``kvmfr0`` would be 128 MB and ``kvmfr1`` would be 64 MB.
|
|
|
|
.. note::
|
|
|
|
If you have already loaded an older version of the module, unload it
|
|
first. You can do this by rebooting, or with ``rmmod``:
|
|
|
|
.. code:: bash
|
|
|
|
rmmod kvmfr.ko
|
|
|
|
.. _module_usage:
|
|
|
|
Usage
|
|
-----
|
|
|
|
The module will create the ``/dev/kvmfr0`` node, which represents the KVMFR
|
|
interface. To use the interface, you need permission to access it by
|
|
either: creating a udev rule to ensure your user can read and write to
|
|
it, or simply change its ownership manually, i.e.:
|
|
|
|
.. code:: bash
|
|
|
|
sudo chown user:user /dev/kvmfr0
|
|
|
|
As an example, you can create a new file in ``/etc/udev/rules.d/99-kvmfr.rules``
|
|
with the following contents::
|
|
|
|
SUBSYSTEM=="kvmfr", OWNER="user", GROUP="kvm", MODE="0660"
|
|
|
|
(replace ``user`` with your username)
|
|
|
|
Usage with Looking Glass is simple, you only need to specify the path to
|
|
the device node, for example:
|
|
|
|
.. code:: bash
|
|
|
|
./looking-glass-client -f /dev/kvmfr0
|
|
|
|
You may also use a config file: ``~/.looking-glass-client.ini``, or
|
|
``/etc/looking-glass-client.ini``.
|
|
|
|
.. code:: ini
|
|
|
|
[app]
|
|
shmFile=/dev/kvmfr0
|
|
|
|
.. _module_vm_to_host:
|
|
|
|
VM->Host
|
|
~~~~~~~~
|
|
|
|
In VM->host mode, use this device in place of the shared memory file.
|
|
|
|
QEMU
|
|
^^^^
|
|
|
|
Add the following arguments to your ``qemu`` command line::
|
|
|
|
-device ivshmem-plain,id=shmem0,memdev=looking-glass
|
|
-object memory-backend-file,id=looking-glass,mem-path=/dev/kvmfr0,size=32M,share=yes
|
|
|
|
.. note::
|
|
|
|
The ``size`` argument must be the same size you passed
|
|
to the ``static_size_mb`` argument when loading the kernel module.
|
|
|
|
libvirt
|
|
^^^^^^^
|
|
|
|
Starting with QEMU 6.2 and libvirt 7.9, JSON style QEMU configuration is the
|
|
default syntax. Users running QEMU 6.2 or later **and** libvirt 7.9 or later,
|
|
should use this XML block to configure their VM for kvmfr:
|
|
|
|
.. code:: xml
|
|
|
|
<qemu:commandline>
|
|
<qemu:arg value='-device'/>
|
|
<qemu:arg value='{"driver":"ivshmem-plain","id":"shmem0","memdev":"looking-glass"}'/>
|
|
<qemu:arg value='-object'/>
|
|
<qemu:arg value='{"qom-type":"memory-backend-file","id":"looking-glass","mem-path":"/dev/kvmfr0","size":33554432,"share":true}'/>
|
|
</qemu:commandline>
|
|
|
|
.. note::
|
|
|
|
- The ``"size"`` tag represents the size of the shared memory device in
|
|
bytes. Once you determine the proper size of the device as per
|
|
:ref:`Determining Memory <client_determining_memory>`, use the figure you
|
|
got to calculate the size in bytes:
|
|
|
|
``size_in_MB x 1024 x 1024 = size_in_bytes``
|
|
|
|
If you are running QEMU older than 6.2 or libvirt older than 7.9, please use
|
|
legacy syntax for IVSHMEM setup:
|
|
|
|
.. code:: xml
|
|
|
|
<qemu:commandline>
|
|
<qemu:arg value='-device'/>
|
|
<qemu:arg value='ivshmem-plain,id=shmem0,memdev=looking-glass'/>
|
|
<qemu:arg value='-object'/>
|
|
<qemu:arg value='memory-backend-file,id=looking-glass,mem-path=/dev/kvmfr0,size=32M,share=yes'/>
|
|
</qemu:commandline>
|
|
|
|
.. note::
|
|
|
|
- Using the legacy syntax on QEMU 6.2/libvirt 7.9 may cause QEMU to
|
|
abort with the following error message:
|
|
"``error: internal error: ... PCI: slot 1 function 0 not available for pcie-root-port, in use by ivshmem-plain``"
|
|
|
|
- Remember to add ``xmlns:qemu='http://libvirt.org/schemas/domain/qemu/1.0'``
|
|
to the ``<domain>`` tag.
|
|
|
|
Running libvirt this way violates AppArmor and cgroups policies, which will
|
|
block the VM from running. These policies must be amended to allow the VM
|
|
to start:
|
|
|
|
- For AppArmor, create ``/etc/apparmor.d/local/abstractions/libvirt-qemu`` if
|
|
it doesn't exist, and add the following::
|
|
|
|
# Looking Glass
|
|
/dev/kvmfr0 rw,
|
|
|
|
- For cgroups, edit ``/etc/libvirt/qemu.conf``, uncomment the
|
|
``cgroup_device_acl`` block, and add ``/dev/kvmfr0`` to the list.
|
|
Then restart ``libvirtd``:
|
|
|
|
.. code:: bash
|
|
|
|
sudo systemctl restart libvirtd.service
|
|
|
|
.. _systemd_modules_load:
|
|
|
|
systemd-modules-load
|
|
~~~~~~~~~~~~~~~~~~~~
|
|
|
|
For convenience, you may load the KVMFR module when starting your computer.
|
|
We can use the ``systemd-modules-load.service(8)`` service for this task.
|
|
|
|
Create the file ``/etc/modules-load.d/kvmfr.conf`` with the following
|
|
contents::
|
|
|
|
#KVMFR Looking Glass module
|
|
kvmfr
|
|
|
|
This will now run the next time you start your machine.
|
|
|
|
If you are running in VM->host mode, you must additionally create another file
|
|
``/etc/modprobe.d/kvmfr.conf`` to properly set the size. It should have the
|
|
following contents::
|
|
|
|
#KVMFR Looking Glass module
|
|
options kvmfr static_size_mb=32
|
|
|
|
.. note::
|
|
|
|
Don't forget to adjust ``static_size_mb`` to your needs.
|