Installation on Windows
Introduction
EPICS
EPICS is a toolkit for building control systems. You can get the basic ideas from the EPICS web site at https://epics-controls.org/about-epics/.
Traditionally, an EPICS installation starts with compiling the core parts (“EPICS Base”) from source. This process is covered by these instructions, starting from scratch on a Windows system and getting you to the point where you have a working IOC and can connect to it from a command line shell. Other How-Tos will guide you further.
EPICS on Windows
While it is not its primary or most widely used target platform, the EPICS low-level libraries have good and well-tested implementations on Windows. EPICS runs fine on Windows targets, fast and robust.
There are, however, a few choices about how to compile and run EPICS on Windows that you will have to take beforehand. Understanding these choices and their implications before making decisions will help you to avoid mistakes and spend time fixing them.
Cygwin
As mentioned before, EPICS Base has its own native Windows implementation of all necessary low level services. There is no need to go through the Posix emulation layer that Cygwin provides. The native Windows implementation is more portable and performs better. Unless you need to use Cygwin, e.g., if you are using a binary vendor-provided library for Cygwin, you should prefer a native Windows build.
Also, Cygwin is deprecated as a target platform for EPICS.
Build Time
The time needed to build EPICS Base depends on a few factors, including the speed of the processor and file system, the compiler used, the build mode (DLL or static), possibly debugging options and others. On a medium sized two-core machine, a complete build of EPICS 7 often takes between 15 and 30 minutes, the 3.15 branch can be built in 6 to 10 minutes.
Use make -j<n> to make use of multiple CPU cores.
Required Tools
C++ compiler: either MinGW (GCC) or Microsoft’s Visual Studio compiler (VS)
archive unpacker (7zip or similar)
GNU Make (4.x)
Perl
Choice 1: Compiler
You will need a C++ compiler with its supporting C++ standard libraries. Two major compilers are supported by EPICS and its build system:
- Microsoft’s Visual Studio compiler (VS)
Probably the most widely used compiler for EPICS on the Windows platform. The “Community Edition” is free to download and use. (You need to have Administrator rights to install it.) Any Visual Studio installation will need the “C++ development” parts for the compiler toolchain to be installed.
EPICS is using the Make build system. You can use the Visual Studio IDE, but EPICS does not provide any project files or configurations for Visual Studio’s own build system.
- MinGW (GCC) - Minimalist GNU for Windows
A compiler toolchain based on the widely-used GNU compilers that - like the VS compiler - generates native Windows executables.
Both compiler toolchains can create shared libraries (DLLs) and static libraries. On a 64bit system, both can create 64bit output (runs on 64bit systems) and 32bit output (runs on both 32bit and 64bit systems).
When using C++, libraries are not compatible between those two compilers toolchains. When generating a binary (e.g., an IOC), all C++ code that is being linked must have been generated uniformly by either VS or MinGW. (The reason is different name mangling for symbol names: a symbol needed for linking an executable will not be found in a library generated with the other compiler, because its name is different there.)
If you need to link against vendor-provided binary C++ libraries, this will most likely determine which compiler you need to use.
Choice 2: Build Environment and Tool Installation
MSYS2
MSYS2 (available for Windows 7 and up) is a pretty complete “feels like Linux” environment. It includes a Linux style package manager (pacman), which makes it very easy to install the MinGW toolchains (32 and 64 bit) and all other necessary tools. It also offers a bash shell. If you are used to working in a Linux environment, you will like working on MSYS2.
MSYS2 can be installed, used and updated (including tools and compilers) without Administrator rights.
As up-to-date MinGW/GCC compilers are an integral part of the package, MSYS2 is strongly recommended for using the MinGW compiler toolchains.
The Visual Studio compilers can also be used from the MSYS2 bash. This needs a one-time setup of an intermediate batch script to get the Visual Studio environment settings correctly inherited. The resulting shell can compile using Visual Studio compilers as well as using MinGW, selected by the EPICS_HOST_ARCH environment variable setting.
Chocolatey
Chocolatey is a package manager for Windows with a comfortable GUI, making it easy to install and update software packages (including the tools needed for building EPICS). In many cases, Chocolatey packages wrap around the native Windows installers of software.
Using Chocolatey needs Administrator rights.
Windows Installers
You can also install the required tools independently, directly using their native Windows installers.
For Perl, both Strawberry Perl and ActivePerl are known to work. Strawberry Perl is more popular; it includes GNU Make (as gmake.exe) and the MinGW/GCC compiler necessary to build the Channel Access Perl module that is part of EPICS Base.
For GNU Make, the easiest way is to use the one included in Strawberry Perl. Otherwise, there is a Windows binary provided on the EPICS web site.
Native Windows installers often need Administrator rights.
Choice 3: Static or DLL Build / Deployment
If you configure the EPICS build system to build your IOCs dynamically (i.e., using DLLs), they need the DLLs they have been linked against to be present on the target system, either in the same directory as the IOC binary or in a directory that is mentioned in the %PATH% environment variable.
Depending on how you plan to deploy your IOCs into the production system, it might be easier to use static builds when generating IOCs. The resulting binaries will be considerably larger, but they will run on any Windows system without providing additional EPICS DLLs.
When running many EPICS IOCs on a single target machine, the shared aspect of a DLL build will lead to smaller memory usage. The DLL is in memory once and used concurrently by all IOC binaries, while the statically linked binaries each have their own copy of the library in memory.
Note: When using the Visual Studio compilers, compilation uses different flags for building DLLs and building static libraries. You can’t generate static and shared libraries in the same build. You can provide both options in your EPICS installation by running both builds in sequence (with make clean inbetween), so that your applications can decide between static or DLL build. Or you can just provide one option globally for your installation, which all installations will have to use.
Windows Path Names
Make based builds do not work properly when there are space characters or parentheses in the paths that are part of the build (including the path where the make application resides and the path of the workspace).
If you cannot avoid paths with such characters, use the Windows short path (can be displayed with dir /x) for all path components with those characters in any path settings and/or your workspace directory.
Put Tools in the PATH
No matter which shell and environment you use, the tools (perl, make) should end up being in the %PATH%, so that they are found when called just by their name.
Install and Build
Depending on your set of choices, the instructions for building EPICS Base, building IOC applications and running them are different. The following detailed instructions focus on two common sets of choices: using MSYS2 with the MinGW Gnu compilers and using the plain Windows command prompt with the Visual Studio compilers.
Setting the environment for building and running applications has to be done for either set of choices.