The idea is correct, but implementation is arguably not. TUNABLE_XXX_FETCH() keeps the variable unchanged if the env var is not present. The correct logic would be

textmode = vm_guest != VM_GUEST_NO;
TUNABLE_INT_FETCH("hw.vga.textmode", &textmode);

This would give the desired behaviour of enabling textmode by default for guests only, but also allowing user to override it as she wants.

In D5739#122559, @kib wrote:

The idea is correct, but implementation is arguably not. TUNABLE_XXX_FETCH() keeps the variable unchanged if the env var is not present. The correct logic would be

textmode = vm_guest != VM_GUEST_NO;
TUNABLE_INT_FETCH("hw.vga.textmode", &textmode);

This would give the desired behaviour of enabling textmode by default for guests only, but also allowing user to override it as she wants.

@kib, Thanks! I'll update the patch as you suggested.