How To Run Spice Agent in Alpine

This is a guide on how to run Spice Agent in Alpine Linux 3.12.1-standard.

The Spice Agent can be used to get some additional features when running Alpine Linux in a Qemu/Libvirt VM.

Features

Working:

Client mouse mode
Automatic adjustment of the X-session resolution
Clipboard sharing

Not working:

The State field in Libvirt - it always shows "disconnected", even when it is working

Not tested:

Transferring files
Multiple displays/screens

Before You Start

Most features of the Spice Agent are only useful when running a graphical interface. I roughly followed the Awesome(wm)_Setup guide, but substituted awesome with i3wm as that has my preference (you have to install i3status manually, and use i3 in the .xinitrc file).

For the Spice Agent to work, don't remove the Channel spice that is automatically added by Libvirt.

Building the Spice Agent

Install the dependencies:

 # apk add alpine-sdk autoconf automake glib-dev libxfixes-dev libxrandr-dev libxinerama-dev spice-protocol alsa-lib-dev dbus-dev libdrm-dev libpciaccess-dev

Get the source code:

 $ git clone https://gitlab.freedesktop.org/spice/linux/vd_agent.git
 $ cd vd_agent
 $ git checkout spice-vdagent-0.20.0

We need this specific version because the newest version requires a newer spice-protocol version than is provided by the repositories (version 0.14.1). If you follow this guide with a later version of Alpine, you may want to get a newer version from git as well.

Build the code (still in the vd_agent directory):

 $ ./autogen.sh
 $ make

Install the program (should be optional, but I haven't tried it without yet):

 # make install

Running the Spice Agent

This material is work-in-progress ...

While this works, it's very rough and the steps need to be performed every time you want to run it. It would be nice to have init scripts to do this.
(Last edited by MartinJM on 11 Nov 2020.)

First start the spice-vdagentd:

 # modprobe uinput
 # mkdir /run/spice-vdagentd
 # spice-vdagentd -d -x -X

You can also remove the lower-case -x flag to deamonize the spice-vdagentd.

Then start the spice-vdagent:

 $ spice-vdagent -x -d

Notice that there is no need to run this last command as root.

Using the virt edition of Alpine

This currently does not work on the virt edition (version 3.12.1), as it doesn't have uinput enabled in the kernel. However, there are still several ways to get it working.

Run without the uinput

You can make the spice-vdagentd work without the uinput module by starting it as follows, but it will disable the cursor while the spice-vdagent is running:

 # mkdir /run/spice-vdagentd
 # spice-vdagentd -d -x -X -u /dev/null -f

Build uinput as module

This material is work-in-progress ...

This will build the module, and it can be loaded, but it doesn't install the module. This has yet to be added.
(Last edited by MartinJM on 11 Nov 2020.)

Follow the steps in Setup your system and account for building packages and cd to the aports/main/linux-lts directory. Check that the kernel version you've pulled is the same that you're running with uname -r and head APKBUILD. If they mismatch, checkout the aports branch that has the same kernel version. If they are the same, continue with the following steps:

 $ abuild deps
 $ abuild fetch verify
 $ abuild unpack
 $ abuild prepare
 $ cd src/build-virt-x86_64

Now change CONFIG_INPUT_UINPUT from not being included to CONFIG_INPUT_UINPUT=m in the .config file. Then proceed as follows:

 $ make modules_prepare
 $ make drivers/input/misc/uinput.ko

This builds the uinput module in the current directory. Every time you want to use it, you'll have to load it like this (still from aports/main/linux-lts/src/build-virt-x86_64):

 # insmod drivers/input/misc/uinput.ko

After this, you can use the spice agent as described in Running the Spice Agent, except that the modprobe uinput is not necessary.

Rebuild the kernel to include uinput

See Custom_Kernel for pointers on how to build a custom kernel. The option you'll need to change in the config is CONFIG_INPUT_UINPUT.