Comment by danhor

> Nothing stops someone from taking the free Windows Vivado and making it run on Linux

The EULA and the fact that the linux versior runs faster & has fewer bugs.

> just the device-dependent backend would be a major improvement and the frontend and optimizer could be shared with other toolchains

That's yosys and it's used by smaller commercial vendors.

> or reverse engineering then bitstream format for these FPGAs

Getting the timing is the hard part (+ good routing afterwards). The bitstream format has AFAIK mostly been reversed. 7 series has mediocre support , but US, US+ and Versal doesn't (probably because they're too expensive for personal usage).