QEMU Emulation for X86

Overview

The X86 QEMU board configuration is used to emulate the X86 architecture.

This board configuration provides support for an x86 Minute IA (Lakemont) CPU and the following devices:

HPET
Advanced Programmable Interrupt Controller (APIC)
NS16550 UART

Hardware

Supported Features

This configuration supports the following hardware features:

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

Devices

HPET System Clock Support

The configuration uses an HPET clock frequency of 25 MHz.

Serial Port

The board configuration uses a single serial communication channel that uses the NS16550 serial driver operating in polling mode. To override, enable the UART_INTERRUPT_DRIVEN Kconfig option, which allows the system to be interrupt-driven.

If SLIP networking is enabled (see below), an additional serial port will be used for it.

Known Problems or Limitations

The following platform features are unsupported:

Isolated Memory Regions
Serial port in Direct Memory Access (DMA) mode
Serial Peripheral Interface (SPI) flash
General-Purpose Input/Output (GPIO)
Inter-Integrated Circuit (I2C)
Ethernet
Supervisor Mode Execution Protection (SMEP)

Programming and Debugging

Applications for the qemu_x86 board configuration can be built and run in the usual way for emulated boards (see Building an Application and Run an Application for more details).

Flashing

While this board is emulated and you can’t “flash” it, you can use this configuration to run basic Zephyr applications and kernel tests in the QEMU emulated environment. For example, with the Basic Synchronization sample:

# From the root of the zephyr repository
west build -b qemu_x86 samples/synchronization
west build -t run

This will build an image with the synchronization sample app, boot it using QEMU, and display the following console output:

***** 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!

Exit QEMU by pressing CTRL+A x.

For qemu_x86_64 platform, it also supports to use UEFI bootable method to run Zephyr applications and kernel tests, but you need to set up some environment configurations as follows:

Please install uefi-run in your system environment according to this reference link https://github.com/Richard-W/uefi-run. Note that uefi-run from snapstore may not work because of strict snap confinements. The preferred method is installing with cargo.
Please install OVMF in your system environment according to this reference link https://github.com/tianocore/tianocore.github.io/wiki/OVMF. The easiest way is to install a special ovmf package found in many distros. For example, use the following command in Ubuntu:
```
sudo apt install ovmf
```
Set system environment variable OVMF_FD_PATH, for example:
```
export OVMF_FD_PATH=/usr/share/OVMF/OVMF_CODE.fd
```

Now you can build application, for example UEFI boot test sample found under tests/boot/uefi:

# From the root of the zephyr repository
west build -b qemu_x86_64 tests/boot/uefi
west build -t run

This will build an image with the uefi boot test app, boot it on qemu_x86_64 using UEFI, and display the following console output:

UEFI Interactive Shell v2.2
EDK II
UEFI v2.70 (EDK II, 0x00010000)
Mapping table
      FS0: Alias(s):F0a:;BLK0:
          PciRoot(0x0)/Pci(0x1,0x1)/Ata(0x0)
     BLK1: Alias(s):
          PciRoot(0x0)/Pci(0x1,0x1)/Ata(0x0)
Press ESC in 1 seconds to skip startup.nsh or any other key to continue.
Starting UEFI application...
*** Zephyr EFI Loader ***
Zeroing 524544 bytes of memory at 0x105000
Copying 32768 data bytes to 0x1000 from image offset
Copying 20480 data bytes to 0x100000 from image offset 32768
Copying 540416 data bytes to 0x185100 from image offset 53248
Jumping to Entry Point: 0x112b (48 31 c0 48 31 d2 48)
*** Booting Zephyr OS build zephyr-v2.6.0-1472-g61810ec36d28  ***
Hello World! qemu_x86_64

Exit QEMU by pressing CTRL+A x.

Debugging

Refer to the detailed overview about Application Debugging.

Networking

The board supports SLIP networking over an emulated serial port (CONFIG_NET_SLIP_TAP=y). The detailed setup is described in Networking with QEMU.

It is also possible to use the QEMU built-in Ethernet adapter to connect to the host system. This is faster than using SLIP and is also the preferred way. See Networking with QEMU Ethernet for details.