Add QNX cross-compilation support

[dchordia]

Hi,
This contribution adds cross-compilation support for QNX operating system to libmetal.

Motivation

QNX is an industry standard real-time operating system for embedded systems, particularly for vehicles, featuring safety focused features. It has also recently been made free for non-commercial use through the QNX Everywhere program, aiming for students, researchers and hobbyists to experiment with the OS.

Given than open-amp is a useful library for supporting AMP in various master slave configurations, it would be great to enable it to run natively on free version of QNX OS.

Description of changes

• Change clashing CACHE_FLUSH definition for QNX compilations

How to build for QNX

The build files and instructions for cross-compiling open-amp for QNX are present at qnx-ports. A free QNX8 license can be obtained here.

By submitting this pull request, I confirm that my contribution is made under the terms of BSD License

[arnopo]

Hello @dchordia,
The open-amp lib should be OS agnostic. Instead of adding specific code for QNX, could we simply remove the CACHE_FLUSH and CACHE_INVALIDATE macro, replacing them by metal_cache_flush and metal_cache_invalidate?

[dchordia]

Sure, I have removed the two macros and replaced their instances with metal_cache_flush and metal_cache_invalidate functions. Note: CACHE_FLUSH is the only conflicting macro with internal QNX definition (ref) but I removed CACHE_INVALIDATE based on your feedback and for consistency

[iuliana-prodan]

Sure, I have removed the two macros and replaced their instances with metal_cache_flush and metal_cache_invalidate functions. Note: CACHE_FLUSH is the only conflicting macro with internal QNX definition (ref) but I removed CACHE_INVALIDATE based on your feedback and for consistency

In this case, patch 1 can be removed from this pull request.
Second patch should be enough.

[dchordia]

I have removed it. Also, checks / checkpatch review was failing due to non compliant commit message. Changed and force pushed correct format

[arnopo]

I have removed it. Also, checks / checkpatch review was failing due to non compliant commit message. Changed and force pushed correct format

Please squash your two commits into one and update the commit message accordingly.

[iuliana-prodan]

LGTM

[tnmysh]

LGTM.