The open62541 core library (in the /src folder) is operating system-independent. The individual integration lives in the /arch folder and in specific plugin implementations in /plugins (e.g. for filesystem access of cryptographic PKI functionality).

open62541 supports all 32/64bit CPU instruction sets. Instruction sets that are known to be little-endian and/or with IEEE 754 floating point representations can use speed-ups for the encoding/decoding of network messages. The generic implementation is slower, but works on all instruction sets.

Operating Systems

open62541 supports many operating systems (also embedded). See the table below for an overview. The operating system support is classified into three tiers:

Tier 1 operating systems have the best support. All code contributions need to pass our continuous integration (CI) infrastructure for these operating systems. For Tier 1 support, the open62541 maintainers (help to) fix bugs in the current "stable" and "oldstable" release families.
Tier 2 operating systems are "known to work", but there is no coverage in the continuous integration (CI) infrastructure. The open62541 maintainers have to manually test against these operating systems. This leads to intermittent breakage and to more undetected bugs in released versions. For tier 2 the maintainers fix known bugs in the current "stable" release family. But they cannot go bug hunting in older release families.
Tier 3 operating systems have no no automated continuous integration (CI) environment and the open62541 maintainers have no permanent access for manual testing. This can lead to releases of open62541 with undetected issues for those OS. There is limited support / code review by the open62541 maintainers to integrate contributions into the master branch.

Operating System	Support Tier
Tier 1
Linux	Tier 1
Windows	Tier 1
MacOS	Tier 1
Zephyr	Tier 1
FreeRTOS	Tier 1
Tier 2
BSD	Tier 2
Tier 3
QNX	Tier 3
vxWorks	Tier 3

The o6 Automation GmbH (https://www.o6-automation.com) is the legal entity launched by the maintainers of open62541. Contact o6 if you need commercial support for open62541. This includes porting or integration of open62541 for your specific needs. The commercial support also allows for long-term support for old release families (besides stable/oldstable). This enables commercial products developed with a specific version of open62541.

Adding New Operating Systems

The OS-specific functionality covers access to the system clock and the EventLoop implementation (Networking, Timed events, Interrupt handling (optional)).

To port open62541 to a new architecture, follow these steps:

Modify the clock.c file that implements the following functions defined in open62541/types.h:
- UA_DateTime UA_DateTime_now(void);
- UA_Int64 UA_DateTime_localTimeUtcOffset(void);
- UA_DateTime UA_DateTime_nowMonotonic(void);
Fork the EventLoop code (the default is POSIX) and adjust it to your architecture. Note that it is not necessary to port all networking subsystems (and interrupts). The library will detect when a certain protocol (e.g. UDP, ETH) is not available. TCP support is however mandatory.
The code for the initial configuration of client/server applications lives in /plugins/ua_config_default.c. Fork/update this code to instantiate your EventLoop implementation in the client/server configuration.

To prevent the parallel build of Win32/POSIX versions, set UA_ARCHITECTURE=none in the cmake setting and link the final binary against your new code files. Otherwise modify /include/open62541/config.h.in and /CMakelists.txt to add permanent support for your operating system.