How to build a sysimage for Windows

General Usage
,
1

I built a system image on Windows 10 using Julia 1.12. But I cannot start Julia with this system image:

C:\Users\ufechner\repos\IM_AWES_bench.jl\bin>julia -J sysimage.dll
ERROR: could not load library "C:\Users\ufechner\repos\IM_AWES_bench.jl\bin\sysimage.dll"
%1 is not a valid Win32 application.

julia> versioninfo()
Julia Version 1.12.6
Commit 15346901f0 (2026-04-09 19:20 UTC)
Build Info:
  Official https://julialang.org release
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: 16 × AMD Ryzen 9 7950X 16-Core Processor
  WORD_SIZE: 64
  LLVM: libLLVM-18.1.7 (ORCJIT, znver4)
  GC: Built with stock GC
Threads: 1 default, 1 interactive, 1 GC (on 16 virtual cores)

Any idea?

Works fine on Linux.

And yes, Windows and Julia are both 64 bit. So the error message is a bit confusing.

2

Any ideas how to debug?

ufechner@ufryzen:~/Shared_Windows$ objdump -f sysimage.dll 

sysimage.dll:     file format pei-x86-64
architecture: i386:x86-64, flags 0x0000013b:
HAS_RELOC, EXEC_P, HAS_DEBUG, HAS_SYMS, HAS_LOCALS, D_PAGED
start address 0x00000003a4d61320
3

Hmm. My one thought is do you have a msys2 environment you could work with?

4

I tested on Windows 11 and got the same error.

You can reproduce the problem like this:

git clone https://github.com/c-nicomar/IM_AWES_bench.jl.git
cd IM_AWES_bench.jl/bin
./install
./create_sys_image
cd ..
./bin/run_julia

Warning: Takes a long time.

5

If this is your main lead, then we need to create a Windows debugging environment. There are two paths, one is to use MSYS2 and use a GCC-based framework to analyze dynamic library loading.

There are also tools like WinDbg:

Essentially, we need to do the eqiuvalent of LD_DEBUG=libs. You’ll need to use gflags.exe that should come with WinDbg to enable logging of shared library loading on the Julia executable.

PackageCompiler.jl does require a C compiler, and I’m not sure which one you are using.

6

How big is the sysimage?

7

How shall I know that? I think PackageCompiler installs its own compiler as an artifact. One of the machines where I tried compiling it is quite virgin, not much on it, definitely no C compiler that I installed myself. I just installed Git for Windows, which comes with a Bash shell.

And a few months ago, this all worked fine.

8 
ufechner@ufryzen:~/Shared_Windows$ ls -la sysimage.dll 
-rwxrwxr-x 1 ufechner ufechner 2208050613 Jul 27 23:21 sysimage.dll
ufechner@ufryzen:~/Shared_Windows$ ls -lah sysimage.dll 
-rwxrwxr-x 1 ufechner ufechner 2.1G Jul 27 23:21 sysimage.dll

const PACKAGES = [
    "ModelingToolkit",
    "OrdinaryDiffEq",
    "MakieControlPlots",
    "CSV",
    "DataFrames",
]

Is that too big?

9

Removing ModelingToolkit from the system image solved the problem:

This works:

const PACKAGES = [
    "OrdinaryDiffEq",
    "MakieControlPlots",
    "CSV",
    "DataFrames",
]

Size now:

ufechner@DESKTOP-USD9U6B MINGW64 ~/repos/InductionMachineDrives.jl/bin
$ ls -la sysimage.dll
-rwxr-xr-x 1 ufechner 197121 1733065543 Jul 31 20:04 sysimage.dll*
$ ls -lah sysimage.dll
-rwxr-xr-x 1 ufechner 197121 1.7G Jul 31 20:04 sysimage.dll*

This looks a bit as if there might be an upper limit of 2 GB on the size of the sysimage on Windows. If that should be the case, PackageCompiler should at least print a warning.

Any comments? Could this be fixed?

10

Yes, limit is 2 GB

That’s a good idea. Add compression option and warn on too big sysimage sizes on windows - Pull Request #1114 - JuliaLang/PackageCompiler.jl - GitHub should warn and also on 1.13 add the compress option that significantly reduces the size of the sysimage (but makes it slightly slower to load).

11

Is there also such a size limit on macOS, or is it only on Windows?

12

There could be something around 4GB for those but I am not 100% sure