Running trs + xen on AVA

Owned by Manos Pitsidianakis
Last updated: Apr 08, 2024
4 min read

EFI / Bootloader

To avoid having to setup the boot options, I enter the EFI Boot menu by pressing Escape during the AVA booting process, then select “Boot Maintenance Manager” → “Boot from file” and select “xen.efi” from the disk where the TRS image is flashed.

Creating the Xen guest

How to change the QEMU invocation command flags for a guest

Using the device_model_override option inside a guest .cfg file we can change the QEMU binary that runs for a guest. The following Python3 script can be used as a device_model_override binary and launch the QEMU build of your choice with the command flags you want.

  • Custom command flags for QEMU go to the hard-coded global variable guest_device_args list in the script’s source code.

  • QEMU Binary path is hard-coded in the QEMU_BINARY_PATH global variable.

  • Environment flags can be set by adding os.environ["ENV_VAR"] = "VALUE" lines.

  • stdout/stderr are redirected to the path in the hard-coded LOG_FILE global variable.

Save the following source code as qemu_device_model.py, set executable permissions with chmod +x qemu_device_model.py and override the xen device model parameter in the guest .cfg file:

device_model_version="qemu-xen" device_model_override="/home/root/qemu_device_model.py"

This will call the script with the same arguments it’d otherwise pass to the QEMU binary.

The source code:

#!/usr/bin/env python3 # SPDX-License-Identifier: GPL-3.0-or-later # <manos.pitsidianakis@linaro.org> import sys, signal, os from subprocess import Popen """ Usage Save as `qemu_device_model.py`, set as executable (`chmod +x qemu_device_model.py`) and add in xen guest .cfg: device_model_version="qemu-xen" device_model_override="/home/root/qemu_device_model.py" """ def handler_exit_signals(signum, frame): raise SystemExit(0) signal.signal(signal.SIGINT, handler_exit_signals) signal.signal(signal.SIGTERM, handler_exit_signals) #os.environ["LD_LIBRARY_PATH"] = "/usr/local/lib/aarch64-linux-gnu" QEMU_BINARY_PATH = "/usr/bin/qemu-system-aarch64" LOG_FILE = "/home/root/qemu_log.txt" args = sys.argv[1:] dom_id = None name = None # print("args are:",args) i = 0 try: while i < len(args): if args[i].startswith("-xen-domid"): dom_id = args[i + 1] i += 2 continue if args[i].startswith("-name"): name = args[i + 1] i += 2 continue i += 1 except IndexError as exc: print(exc, "for i =", i) print("Invalid command line arguments: ", args) sys.exit(1) if name is None: name = "trs-vm" if dom_id is None: print("No -xen-domid found in arguments:\nArguments were:", args) sys.exit(1) libxl_cmd_socket = "/var/run/xen/qmp-libxl-{}".format(dom_id) libxenstat_cmd_socket = "/var/run/xen/qmp-libxenstat-{}".format(dom_id) # Create new argv with flags that include the domid and guest name first, then # add the device flags xen_guest_specific_args = [ "-name", name, "-xen-domid", dom_id, "-chardev", "socket,id=libxl-cmd,path={},server=on,wait=off".format(libxl_cmd_socket), "-chardev", "socket,id=libxenstat-cmd,path={},server=on,wait=off".format(libxenstat_cmd_socket), "-mon", "chardev=libxl-cmd,mode=control", "-mon", "chardev=libxenstat-cmd,mode=control", "-nodefaults", "-no-user-config", "-xen-attach", "-no-shutdown", "-smp", "4,maxcpus=4", "-machine", "xenpvh", "-m", "6144", ] guest_device_args = [ "-vga", "std", "-vnc", "none", "-display", "sdl,gl=on", "-device", "virtio-gpu-pci,disable-legacy=on,iommu_platform=on,xres=1080,yres=600", "-global", "virtio-mmio.force-legacy=false", "-device", "virtio-mouse-pci,disable-legacy=on,iommu_platform=on", "-device", "virtio-keyboard-pci,disable-legacy=on,iommu_platform=on", "-device", "virtio-snd-pci,audiodev=snd0,disable-legacy=on,iommu_platform=on", "-audiodev", "alsa,id=snd0,out.dev=default", ] new_args = [QEMU_BINARY_PATH] + xen_guest_specific_args + guest_device_args # print("new args are:",new_args) with open(LOG_FILE, "a") as log, Popen(new_args, stdout=log, stderr=log) as proc: try: proc.wait() except SystemExit: proc.kill() sys.exit(proc.returncode)

Create guest

xl create /path/to/guest.cfg

Inspect guest domain state:

Sometimes, QEMU doesn’t exit cleanly and the guest shows up as (null) . Issue pkill qemu and it should go away.

Attach to guest console

where GUEST_NAME is the value of "name" in the guest configuration.

Example guest .cfg file