引用一下Spec原文,因為我覺得他們說的比我說的清楚多了“The Interrupt Pin register tells which interrupt pin the device (or device function) uses. A value of 1 corresponds to INTA#. A value of 2 corresponds to INTB#. A value of 3 corresponds to INTC#. A value of 4 corresponds to INTD#. Devices (or device functions) that do not use an interrupt pin must put a 0 in this register. The values 05h through FFh are reserved. This register is read-only. Refer to Section 2.2.6. for further description of the usage of the INTx# pins.”PCI設備要處理數據,它的數據也肯定最終是要讓CPU來處理的,與CPU的通信的話PCI設備是通過中斷來實現的。而Interrupt Pin只是標誌了HW上用了INTx中的哪一個。這個與PCI IRQ routing table有關係了。後續篇章里我會繼續談到。