X86 Emulation (QEMU)¶

Overview¶

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

Qemu (Credit: qemu.org)¶

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 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.

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.