Intel wrote:In most systems, the DPLs of TSS descriptors are set to values less than 3, so that only privileged software can
perform task switching. However, in multitasking applications, DPLs for some TSS descriptors may be set to 3 to
allow task switching at the application (or user) privilege level.
It makes sense to me that most operating systems don't want i386 task switching to be triggered by user apps, without getting a #GPF. Is there some subtle detail I'm missing?