UWM_SWITCH_STACK
if (u->flags & UWM_SWITCH_STACK) {
TEST_WITH_FLAGS(UWM_SWITCH_STACK),
TEST_WITH_FLAGS(UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK),
TEST_WITH_FLAGS(UWM_IRQ | UWM_SWITCH_STACK),
TEST_WITH_FLAGS(UWM_IRQ | UWM_CALLER | UWM_SP | UWM_REGS | UWM_SWITCH_STACK),