Concurrency with Interrupts:Challenges Thread X Handler 0 Thread Y irq0 sti Handler 1 switch irq1 4) cli iret switch cli iret sti _switch sti Asymmetric preemption between handlers and non-handler code Intertwining between threads and handlers Asymmetric synchronization:cli/sti are different from locksConcurrency with Interrupts: Challenges . . . . . . cli . . . switch . . . sti . . . Thread X switch iret . . . . . . Handler 0 . . . cli . . . switch . . . sti . . . . . . sti . . . Thread Y iret . . . Handler 1 Asymmetric preemption between handlers and non-handler code Intertwining between threads and handlers Asymmetric synchronization: cli/sti are different from locks