SIGCHLD_IRQ
#define VECTOR_BASE_IRQ (SIGCHLD_IRQ + 1)
#define UM_FIRST_DYN_IRQ (SIGCHLD_IRQ + 1)
do_IRQ(SIGCHLD_IRQ, regs);
err = request_irq(SIGCHLD_IRQ, mm_sigchld_irq, 0, "SIGCHLD", NULL);