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QNX Hypervisor
The QNX Hypervisor allows you to run multiple OSs on a target system so you can separate critical and non-critical functions, support a wide variety of applications, and reduce hardware costs.
QNX Hypervisor for Safety Virtual Device Developer's API Reference
vio.h
Definitions for VIRTIO vdevs
vio_iov
Structure for converting a virtqueue descriptor list into an iov_t array

QNX Momentics IDE User's Guide
This User's Guide describes version 7.1 of the Integrated Development Environment (IDE) that's part of the QNX Momentics tool suite.
QNX Software Development Platform
QNX SDP is a cross-compiling and debugging environment, including an IDE and command-line tools, for building binary images and programs for target boards running QNX Neutrino 7.1.
QNX Hypervisor
The QNX Hypervisor allows you to run multiple OSs on a target system so you can separate critical and non-critical functions, support a wide variety of applications, and reduce hardware costs.
- QNX Hypervisor for Safety User's Guide
- QNX Hypervisor for Safety Virtual Device Developer's Guide
- QNX Hypervisor for Safety Virtual Device Developer's API Reference
  - Function Safety
    This section provides an overview of the restrictions that may apply when using the functions in this API.
  - aarch64/vmid.h
    Definitions to access a guest's VMID (ARM)
  - abi.h
    Application binary interface (ABI) version of the vdev API
  - cdev.h
    Functions to create virtual character devices for guests
  - firmware.h
    Functions for working with the firmware components of the VM presented to the guest
  - gasp.h
    Functions for working in guest address spaces
  - guest.h
    Definitions for manipulating a guest system
  - hpci.h
    Host PCI interface for vdevs
  - hw_pci.h
    PCI support for vdevs
  - outpipe.h
    Definitions for the output pipe (outpipe)
  - types.h
    vdev API base types
  - utils.h
    Miscellaneous utility functions
  - vdev.h
    Source compatibility header file
  - vdev-core.h
    Definitions for vdevs
  - vio.h
    Definitions for VIRTIO vdevs
    - Definitions in vio.h
      Preprocessor macro definitions for the vio.h header file
    - vio_append_iov()
      Extend an iov array to cover an additional VIRTIO descriptor
    - vio_append_iov_cap()
      Extend an iov array to cover an additional VIRTIO descriptor, up to a maximum length
    - vio_config_update()
      Inform the driver that the device has modified its configuration
    - vio_control_status()
      Function called by the control function to output the vdev's status information
    - vio_ctrl_pci_bars()
      Handle VDEV_CTRL_PCI_BARS for vdevs
    - vio_description
      Information describing the VIRTIO device to be created
    - vio_device_status()
      Update the VIRTIO status register for the device
    - vio_get_iov()
      Convert a VIRTIO descriptor request into an iov array
    - vio_init()
      Initialize the vdev's state
    - vio_init_queue()
      Initialize a single virtqueue in the device
    - vio_iov
      Structure for converting a virtqueue descriptor list into an iov_t array
    - vio_iov_flags
      Flag specifying if a host-physical address is required
    - vio_iov_set_flags()
      Handle setting or clearing flags in a vio_iov structure
    - vio_prepare_iov()
      Set the required fields for one logical sequence of calls to vio_append_iov()
    - vio_put_iov()
      Finish handling a VIRTIO request
    - vio_queue_info
      Information for one virtqueue on the device
    - vio_read()
      Handle a read reference for a vdev
    - vio_reset()
      Re-initialize the device
    - vio_setup_queues()
      Get host virtual addresses for the virtqueue rings
    - vio_state
      State of a VIRTIO vdev
    - vio_version
      Version of the VIRTIO standard the device is implementing
    - vio_write()
      Handle a write reference for a vdev
  - vpci.h
    Definitions for virtual PCI devices
  - wdog.h
    Definitions to support virtual watchdog devices
  - x86_64/apic.h
    Definitions for the virtual APIC bus (x86)
- QNX Hypervisor User's Guide
QNX Software in the Cloud
QNX Software in the Cloud enables developers to use the QNX software in Amazon Web Services (AWS) and Microsoft Azure (Azure).
QNX Advanced Virtualization Frameworks User's Guide
This User's Guide is aimed at all systems integrators and developers who want to design and build embedded systems using the QNX Advanced Virtualization Frameworks.
Typographical Conventions, Support, and Licensing
This section describes the typographical conventions used throughout the documentation and explains how to obtain technical support.

vio_iov

Structure for converting a virtqueue descriptor list into an iov_t array

Synopsis:

#include <qvm/vio.h>

struct vio_iov {
    iov_t* vi_iov;
    struct __iovec64* vi_paddrs;
    int vi_iov_len;
    int vi_reserved;
    unsigned vi_flags;
    unsigned vi_hdr_len;
    int vi_count;
    int vi_payload;
} ;

Data:

iov_t* vi_iov: Actual I/O vector.
struct __iovec64* vi_paddrs: Physical addresses, if requested.
int vi_iov_len: Size of allocated array in vi_iov.
int vi_reserved: Number of entries to reserve for the caller's use.
unsigned vi_flags: vio_iov_flags values.
unsigned vi_hdr_len: Size of the expected header.
int vi_count: Number of entries mapped in vi_iov.
int vi_payload: Index at which payload starts.

Description:

The vdev will likely re-use the vio_iov structure for multiple calls to vio_get_iov().

The vi_hdr_len member of vio_iov is usually expected to be constant through the life of the current structure. It is usually best to set its value immediately after initially zeroing the structure.

Page updated: March 12, 2026