Interrupt
如何知道一個 IRQ 值是否可以免費使用
如果我們添加一個不支持 PNP（Plug-an Play）的設備，製造商將希望提供關於如何為其分配 IRQ 值的明確說明。
但是，如果我們不知道要指定什麼 IRQ 值，應該使用什麼命令行來檢查 IRQ 值是否空閒？
lsdev顯示有關設備的資訊：$lsdev Device DMA IRQ I/O Ports ------------------------------------------------ 0000:00:02.0 7000-703f 0000:00:1f.2 7060-707f 7080-7087 7088-708f 7090-7093 7094-7097 0000:00:1f.3 efa0-efbf 0000:01:00.0 6000-607f 0000:04:00.0 4000-40ff 0000:05:00.0 3000-30ff acpi 9 ACPI 1800-1803 1804-1805 1808-180b 1810-1815 1820-182f 1850-1850 ahci 43 7060-707f 7080-7087 7088-708f 7090-7093 7094-7097 cascade 4這個 cmd 怎麼樣
lsdev，這個任務夠嗎？例如，如果我們想知道 1233 是否空閒，我們將執行以下命令：lsdev | awk '{print $3}'|grep 1233注意：
$3使用上面是因為 IRQ 值列印在lsdev輸出的第 3 列中。那麼如果沒有輸出，是否意味著我們可以免費使用呢？
查看手冊頁
lsdev有以下評論：該程序僅顯示核心對存在哪些硬體的想法，而不是實際可用的硬體。
的輸出
lsdev實際上只是/proc/interrupts文件的內容：摘自
man proc/proc/interrupts This is used to record the number of interrupts per CPU per IO device. Since Linux 2.6.24, for the i386 and x86_64 architectures, at least, this also includes interrupts internal to the system (that is, not associated with a device as such), such as NMI (non‐ maskable interrupt), LOC (local timer interrupt), and for SMP systems, TLB (TLB flush interrupt), RES (rescheduling interrupt), CAL (remote function call interrupt), and possibly others. Very easy to read formatting, done in ASCII.所以我可能會
/proc/interrupts改用以下內容：$ cat /proc/interrupts CPU0 CPU1 CPU2 CPU3 0: 157 0 0 0 IO-APIC-edge timer 1: 114046 13823 22163 22418 IO-APIC-edge i8042 8: 0 0 0 1 IO-APIC-edge rtc0 9: 863103 151734 155913 156348 IO-APIC-fasteoi acpi 12: 2401994 396391 512623 477252 IO-APIC-edge i8042 16: 555 593 598 626 IO-APIC-fasteoi mmc0 19: 127 31 83 71 IO-APIC-fasteoi ehci_hcd:usb2, firewire_ohci, ips 23: 32 8 21 16 IO-APIC-fasteoi ehci_hcd:usb1, i801_smbus 40: 5467 4735 1518263 1230227 PCI-MSI-edge ahci 41: 1206772 1363618 2193180 1477903 PCI-MSI-edge i915 42: 267 5142231 817 590 PCI-MSI-edge iwlwifi 43: 5 8 6 4 PCI-MSI-edge mei_me 44: 0 2 2 23405 PCI-MSI-edge em1 45: 19 66 39 23 PCI-MSI-edge snd_hda_intel NMI: 12126 25353 28874 26600 Non-maskable interrupts LOC: 29927091 27300830 30247245 26674337 Local timer interrupts SPU: 0 0 0 0 Spurious interrupts PMI: 12126 25353 28874 26600 Performance monitoring interrupts IWI: 634179 806528 600811 632305 IRQ work interrupts RTR: 5 1 1 0 APIC ICR read retries RES: 4083290 3763061 3806592 3539082 Rescheduling interrupts CAL: 16375 624 25561 737 Function call interrupts TLB: 806653 778539 828520 806776 TLB shootdowns TRM: 0 0 0 0 Thermal event interrupts THR: 0 0 0 0 Threshold APIC interrupts MCE: 0 0 0 0 Machine check exceptions MCP: 416 416 416 416 Machine check polls ERR: 0 MIS: 0參考