I remember Nvidia getting hacked pretty bad a few years ago. IIRC, the hackers threatened to release everything they had unless they open sourced their drivers. Maybe they got what they wanted. [0] https://portswigger.net/daily-swig/nvidia-hackers-allegedly-...
It's simply a function of their history. They used to have high priced professional level graphics cards ("Nvidia Quadro") using exactly the same chips as their consumer graphics cards.
The BIOS of the cards was different, enabling different features. So people wanting those features cheaply would buy the consumer graphics cards and flash the matching Quadro BIOS to them. Worked perfectly fine.
Nvidia naturally wasn't happy about those "lost sales", so began a game of whack-a-mole to stop BIOS flashing from working. They did stuff like adding resistors to the boards to tell the card whether it was a Geforce or Quadro card, and when that was promptly reverse engineered they started getting creative in other ways.
Meanwhile, they couldn't really Open Source their drivers because then people could see what the "Geforce vs Quadro" software checks were. That would open up software countermeasures being developed.
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In the most recent few years the professional cards and gaming cards now use different chips. So the BIOS tricks are no longer relevant.
Which means Nvidia can "safely" Open Source their drivers now, and they've begun doing so.
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Note that this is a copy of my comment from several months ago, as it's just as relevant now as it was then: https://news.ycombinator.com/item?id=38418278