# What Was Your Biggest “Wait, What?” Moment in Mojo?

**URL:** <https://forum.modular.com/t/what-was-your-biggest-wait-what-moment-in-mojo/2774>\
**Category:** Mojo\
**Created:** [February 25, 2026, 8:42pm UTC](https://forum.modular.com/t/what-was-your-biggest-wait-what-moment-in-mojo/2774 "2026-02-25T20:42:48Z")\
**Posts on this page:** 1\
**Showing post:** 34

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**Author:** ![maxchisto](https://sea1.discourse-cdn.com/flex001/user_avatar/forum.modular.com/maxchisto/32/948_2.png) [@maxchisto](https://forum.modular.com/u/maxchisto)\
**Post date:** [March 13, 2026, 12:40am UTC](https://forum.modular.com/t/what-was-your-biggest-wait-what-moment-in-mojo/2774/34 "2026-03-13T00:40:30Z")

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> What made you want to throw your hands up or walk away?

Lack of guidance on calling Mojo from C and other languages besides Python, and what’s possible/impossible at this moment.

I’m working on a more ambitious followup to [From OpenCL towards Mojo GPU kernels in digital photo editing (first look)](https://forum.modular.com/t/from-opencl-towards-mojo-gpu-kernels-in-digital-photo-editing-first-look/2764) which involves rewriting performance critical parts of a C project and OpenCL kernels that come with it (Darktable) in Mojo.  
Having a tough time understanding why the same kernel runs ok when the target is cpu, but segfaults on gpu specifically when called from a C program.  
I might be doing something obviously wrong or have run into a known problem? - idk, can’t tell

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