Just a question about Jetson TX1 and its relationship with Qt 5.7 (at least 5.7).
With Qt it’s possible to bypass X11 and use its QPA backends such as FB and EGLFS.
For some Tegra boards, I know this is not possible. For example, for the Nvidia Tegra T20, HW acceleration os managed only with X11 support.
What about the NVIDIA TX1 ?
The Xorg server ABI is how the GPU is accessed if direct hardware access is used (software framebuffer is a different story). One does not have to run a graphical desktop, nor a login manager, but the Xorg X11 server must exist to use hardware acceleration (X11 takes a window manager or login manager as an argument in a default Linux install, but this could be modified to instead run some other X11-compliant application directly). The Tegra 4 did not have a GPU, but starting at Tegra K1 a GPU exists…so this is when Xorg becomes mandatory.
Btw, running Qt in a framebuffer without a desktop is still running X11…you’ve bypassed the window manager, not X11.