Using Xenomai as User VM OS (Real-Time VM)¶

Xenomai is a versatile real-time framework that provides support to user space applications that are seamlessly integrated into Linux environments.

This tutorial describes how to run Xenomai as the User VM OS (Real-Time VM) on the ACRN hypervisor.

Build the Xenomai kernel¶

Follow these instructions to buid the Xenomai kernel:

Clone the Xenomai kernel souce code:

$ git clone -b F/4.19.59/base/ipipe/xenomai_3.1 https://github.com/intel/linux-stable-xenomai

Go to the directory and select the default ACRN configuration:
```
$ cd linux-stable-xenomai && make acrn_defconfig
```
Build the kernel:
```
$ make targz-pkg
```

Upon building completion, verify that you see a tarball that contains the kernel and its modules.

$ ls -l
total 97944
drwxr-xr-x  27 tw tw     4096 Feb 20 10:23 arch
drwxr-xr-x   3 tw tw    12288 Feb 21 11:01 block
-rw-r--r--   1 tw tw   789264 Feb 25 16:17 built-in.a
drwxr-xr-x   2 tw tw     4096 Feb 21 11:01 certs
-rw-r--r--   1 tw tw      423 Feb 20 10:17 COPYING
-rw-r--r--   1 tw tw    98741 Feb 20 10:17 CREDITS
drwxr-xr-x   4 tw tw    12288 Feb 21 11:01 crypto
drwxr-xr-x 120 tw tw    12288 Feb 20 10:17 Documentation
drwxr-xr-x 143 tw tw     4096 Feb 21 10:48 drivers
drwxr-xr-x   2 tw tw     4096 Feb 20 10:21 firmware
drwxr-xr-x  73 tw tw    12288 Feb 21 11:01 fs
drwxr-xr-x  32 tw tw     4096 Feb 20 10:19 include
drwxr-xr-x   2 tw tw     4096 Feb 25 16:25 init
drwxr-xr-x   2 tw tw     4096 Feb 21 11:01 ipc
-rw-r--r--   1 tw tw     2245 Feb 20 10:17 Kbuild
-rw-r--r--   1 tw tw      563 Feb 20 10:17 Kconfig
drwxr-xr-x  20 tw tw    12288 Feb 25 16:17 kernel
drwxr-xr-x  13 tw tw    20480 Feb 21 11:01 lib
drwxr-xr-x   5 tw tw     4096 Feb 20 10:17 LICENSES
-rw-r--r--   1 tw tw 17572590 Feb 25 16:17 linux-4.19.59-xenomai-3.1-acrn+-x86.tar.gz
...

Launch the RTVM¶

Prepare a dedicated disk (NVMe or SATA) for the RTVM; in this example, we use /dev/sda.
1. Download the Preempt-RT VM image:
  
  $ wget https://github.com/projectacrn/acrn-hypervisor/releases/download/acrn-2020w01.1-140000p/preempt-rt-32030.img.xz
2. Decompress the xz image:
  
  $ xz -d preempt-rt-32030.img.xz
3. Burn the Preempt-RT VM image onto the SATA disk:
  
  $ sudo dd if=preempt-rt-32030.img of=/dev/sda bs=4M oflag=sync status=progress iflag=fullblock seek=0 conv=notrunc

Launch the RTVM via our script. Indicate the location of the root partition (sda3 in our example) and the kernel tarball:

$ sudo /usr/share/acrn/samples/nuc/launch_xenomai.sh -b /dev/sda3 -k /path/to/linux-4.19.59-xenomai-3.1-acrn+-x86.tar.gz

Verify that a login prompt displays:

...
[  OK  ] Started Permit User Sessions.
[  OK  ] Started Getty on tty1.
[  OK  ] Started Serial Getty on hvc0.
[  OK  ] Reached target Login Prompts.
[  OK  ] Started Network Manager Script Dispatcher Service.
[  OK  ] Started Proxy AutoConfig runner service.
[  OK  ] Started Login Service.
[  OK  ] Reached target Multi-User System.
[  OK  ] Reached target Graphical Interface.

clr-c1ff5bba8c3145ac8478e8e1f96e1087 login:

Install the Xenomai libraries and tools¶

To build and install Xenomai tools or its libraries in the RVTM, refer to the official Xenomai documentation. Note that the current supported version is Xenomai-3.1 with the 4.19.59 kernel.