Jailhouse cell X86 Emulation (QEMU)

Overview

The X86 Jailhouse QEMU board configuration is used to emulate the X86 architecture. This board configuration provides support for x86 64-bit (KVM) passthrough CPUs (-cpu kvm64) and the following devices:

  • Advanced Programmable Interrupt Controller (APIC)
  • NS16550 UART

This is to prove that Zephyr, with this Jailhouse port, would run on any x86-64 CPUs baremetal as well. The port only reaches the UART via port I/O, now, but it can be extended to do MMIO.

Hardware

Supported Features

This configuration supports the following hardware features:

Interface Controller Driver/Component
APIC on-chip interrupt controller
NS16550 UART on-chip serial port

Devices

Serial Port

The board configuration uses a single serial communication channel that uses the NS16550 serial driver operating in polling mode (port I/O is used).

Known Problems or Limitations

The following platform features are unsupported:

  • Serial port in Direct Memory Access (DMA) mode
  • Serial Peripheral Interface (SPI) flash
  • General-Purpose Input/Output (GPIO)
  • Inter-Integrated Circuit (I2C)
  • Ethernet

Programming and Debugging

Use this configuration to run basic Zephyr applications and kernel tests in a QEMU emulated environment (we assume the same QEMU configuration used to accommodate Jailhouse’s configs/qemu-x86.c root cell configuration).

For example, with the Synchronization Sample:

# On Linux/macOS
cd $ZEPHYR_BASE/samples/synchronization
mkdir build && cd build

# On Windows
cd %ZEPHYR_BASE%\samples\synchronization
mkdir build & cd build


# Use cmake to configure a Ninja-based build system:
cmake -GNinja -DBOARD=x86_jailhouse -DJAILHOUSE_QEMU_IMG_FILE=some/valid.qcow2 ..

# Now run ninja on the generated build system:
ninja
ninja run

This assumes the user has the binary qemu-system-x86_64 in their system (not provided by Zephyr’s toolchain). This is because the base system here will be 64-bit and Zephyr will boot as a virtual guest in it. The variable JAILHOUSE_QEMU_IMG_FILE is the path to a .qcow2 file. This qcow2 image must contain the base image with Jailhouse installed (not provided by Zephyr’s SDK, again).

This will build an image with the synchronization sample app and mount the current directory inside QEMU under /mnt.

From a console, in that QEMU instance, issue:

$ sudo insmod <path to jailhouse.ko>
$ sudo jailhouse enable <path to configs/qemu-x86.cell>
$ sudo jailhouse cell create <path to configs/tiny-demo.cell>
$ sudo mount -t 9p -o trans/virtio host /mnt
$ sudo jailhouse cell load tiny-demo /mnt/zephyr.bin
$ sudo jailhouse cell start tiny-demo
$ sudo jailhouse cell destroy tiny-demo
$ sudo jailhouse disable
$ sudo rmmod jailhouse

This should display the following console output:

Created cell "tiny-demo"
Page pool usage after cell creation: mem 275/1480, remap 65607/131072
Cell "tiny-demo" can be loaded
CPU 3 received SIPI, vector 100
Started cell "tiny-demo"
***** BOOTING ZEPHYR OS v1.8.99 - BUILD: Jun 27 2017 13:09:26 *****
threadA: Hello World from x86!
threadB: Hello World from x86!
threadA: Hello World from x86!
threadB: Hello World from x86!
threadA: Hello World from x86!
threadB: Hello World from x86!
threadA: Hello World from x86!
threadB: Hello World from x86!
threadA: Hello World from x86!
threadB: Hello World from x86!

Debugging

Refer to the detailed overview about Custom Board and SOC Definitions.