Linux drivers stop vsyncing with GLX_ARB_create_context. Legacy context creation (i.e. glXCreateContext) works fine.
I am developing a VR application where VSync is of utmost importance.
Ordinarily, I use glXSwapIntervalSGI to enable VSync. Everything seems to work fine as long as I create the OpenGL context with glXCreateContext. If I try to use glXCreateContextAttribsARB, VSync stops working completely (glXSwapIntervalSGI completes successfully, but VSync stays off). I cannot force VSync through the drivers either - setting VSync to "always on" does not change anything.
This is on linux x86_64, using an HD 4850 (the final program will run on workstation graphics). Problem is reproducible with Catalyst 9.1, 9.2 and the 9.4 beta.