[jalbertoni]

I once did some low-level GPU programming on a project aimed for the Samsung Galaxy S8. It was a case with extra features like an iris and fingerprint scanner, connected via the USB port.

It would work perfectly on our test phone and occasionally crash on other phones. Long story short, we narrowed it down to it crashing on phones with a specific SoC that was used in other parts of the world.

For some reason, when you copied an image straight from the phone camera (used to recognize and align eyes compared to the infrared iris camera) to the GPU and tried to access it, it would segfault in the non-western SoC. The data wasn't initialized yet.

My (hurried, we were releasing next month) fix was to add a rsdebug("This fixes a crash!\0"); to the code. The extra delay to go to the kernel and back fixed the race condition almost all the time. Someone later fixed my code from 99.99% stable to 100%, but I was in another project by that time, so I have no idea what they did.