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# QNX Neutrino

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QNX Neutrino
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## Thread priority

QNX supports a total of 256 scheduling priority levels. A non-root thread can set its priority to a level from 1 to 63 (the highest priority).

Using priorities higher than 63 is only possible if  the allowed priority range is changed for non-root processes:

```console
$ procnto -P priority
```

For more information on changing the priority range refer to the QNX documentation.

#### ATTENTION
Not changing the priority range leads to poor timing performance!

## Unbind Ethernet Driver instance

The network interface must be unloaded if it is used by an operating system driver. Depending on the QNX version, a corresponding command must be executed in the QNX Shell or the QNX Build Script.

QNX >= 6.5
: ```console
  $ ifconfig en1 destroy
  ```

QNX >= 7.1
: ```console
  $ umount /dev/io-sock/devs-em.so/em1
  ```

## IOMMU/SMMU support

For systems that have to use an IOMMU/SMMU for security reasons, it is possible to create a predefined typed memory region that is used by the Real-time Ethernet Driver. The definition has to be done in the QNX BSP build file and the name must match following pattern:

**smm_** *LinkLayerName* **-** *InstanceNumber(32Bit Hex)*

Example: Real-time Ethernet Driver emllIntelGbe with instance number 1
: ```default
  smm_emllIntelGbe-0x00000001
  ```

A separate typed memory region must be defined for each Real-time Ethernet Driver instance. The typed memory is automatically used by the Real-time Ethernet Driver if it matches the pattern, otherwise the default memory is used.

## OS Compiler settings

Besides the general settings from [OS Compiler settings](architecture_sdk.html.md#compile-ecdemo) the following settings are necessary to build the example application for QNX Neutrino.

Extra include paths
: ```default
  <InstallPath>/SDK/INC/QNX
  <InstallPath>/Examples/Common/QNX
  ```

Extra source paths
: ```default
  <InstallPath>/Examples/Common/QNX
  <InstallPath>/Sources/OsLayer/QNX
  ```

Extra library paths to the main EtherCAT® components
: ```default
  <InstallPath>/SDK/LIB/QNX/<Arch>
  ```

Extra libraries (in this order)
: ```default
  EcSimulatorRasServer EcSimulator socket
  ```