x86 interrupt and exception

#Interrupt

init

native_init_IRQ() -> set_intr_gate(i, irq_entries_start…
irq_entries_start define in arch/x86/kernel/entry_32.S

##Interrupt Context terminology
* interrupt context - in_irq or in_interrupt
irq_enter
* bh context - in_softirq
local_bh_disable
__do_softirq -> __local_bh_disable_ip