 With the introduction of x86 instructions for system call (SYSENTER/SYSEXIT by Intel and SYSCALL/SYSRET by AMD), a new faster mechanism was introduced for control transfers for x86 programs.As most other architectures do not support call gates, their use was rare even before these new instructions, as software interrupts or traps were preferred for portability, even though call gates are significantly faster than interrupts.Call gates are more flexible than the SYSENTER/SYSEXIT and SYSCALL/SYSRET instructions since unlike the latter two, call gates allow for changing from an arbitrary privilege level to an arbitrary (albeit higher or equal) privilege level.