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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
utils.h
Miscellaneous utility functions
qvm_msgblock_oneshot()
Set a maximum message timeout on the next MsgSend

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
    - Definitions in utils.h
      Preprocessor macro definitions for the utils.h header file
    - next_pow2()
      Round up to the next power of 2
    - qvm_block_string()
      Build a human-readable name for a state block
    - qvm_block_type_name()
      Return a string representation of a block type
    - qvm_callback
      The data structure to use for qvm callback functions
    - qvm_callback_func_t
      Generic qvm callback function
    - qvm_callback_pulse()
      Fill in a sigevent structure to call a function when the event gets delivered
    - qvm_channel()
      Return the qvm process channel ID
    - qvm_dcache_op
      Data cache operations
    - qvm_dcache_operation()
      Perform data cache management
    - qvm_make_non_safety()
      Identify that a process is no longer running in a safety-certified environment
    - qvm_msgblock_oneshot()
      Set a maximum message timeout on the next MsgSend
    - qvm_msgblock_start()
      Set a maximum message time allowed for a block of MsgSends
    - qvm_msgblock_stop()
      Mark the end of a block of MsgSends
    - qvm_overlap()
      Determine if two memory ranges overlap
    - qvm_parse_block()
      Parse a string to populate a structure that describes a data element
    - qvm_parse_intr()
      Parse a guest interrupt specification
    - qvm_parse_num()
      Parse a number from a character string
    - qvm_parse_num_flags
      Flags to control number-parsing operations
    - qvm_register_setvar()
      Add a new set variable to list of available ones
    - qvm_safety_env()
      Check if the current process is running in a safety environment
    - qvm_setvar_context
      Set variable contexts
    - qvm_setvar_info
      Set variable information
    - qvm_setvar_type
      Set variable types
    - qvm_setvar_value
      Union for variable information
    - qvm_slice()
      Given a starting offset and length, calculate the resulting slice array according to a descriptor array
    - qvm_slice_descriptor
      A structure that describes a specified range of offsets in a state structure
    - qvm_slice_result
      A structure describing which descriptor is used for a specified slice, and the size in bytes of the slice
    - qvm_slice_sort()
      Given a slice descriptor, sort its data
    - qvm_slice_store()
      Given a slice descriptor, store state data
    - qvm_unique()
      Obtain a system-wide unique number
  - vdev.h
    Source compatibility header file
  - vdev-core.h
    Definitions for vdevs
  - vio.h
    Definitions for VIRTIO vdevs
  - 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.

qvm_msgblock_oneshot()

Set a maximum message timeout on the next MsgSend

Synopsis:

#include <qvm/utils.h>

int qvm_msgblock_oneshot(const vdev_t *vdp,
                         unsigned mult)

Arguments:

vdp: A pointer to a virtual device (vdev) or NULL for all vdevs in this VM.
mult: The multiplier of the configured timeout.

Description:

This function sets the maximum message timeout for the next MsgSend (i.e., a single MsgSend) only.

To set the maximum message timeout for a block of multiple MsgSends, call qvm_msgblock_start().

To configure default timeouts, use the qvm set option's message-block-timeout and vdev-message-block-timeout options (see the set section in the "VM Configuration Reference" chapter in the QNX Hypervisor for Safety User's Guide).

Returns:

EOK if successful; otherwise an errno value.

Page updated: March 12, 2026