我在 Hummingboard（一個基於 iMX6 的 ARM SBC）上執行 Debian Jessie。
root@torpedo:~# uname -a
Linux torpedo 4.11.4-cubox #2 SMP Tue Jun 13 14:51:52 CEST 2017 armv7l GNU/Linux
它有一個迷你 PCI Express 插槽，我計劃將其用於 4 埠 UART 卡。我有一個Diamond Systems 的卡，使用 EXAR XR17V354 UART 晶片。
作為一個樂觀主義者，我插上卡並啟動，希望能有最好的結果。
看起來該卡已被識別：
root@torpedo:~# lspci -v
00:00.0 PCI bridge: Synopsys, Inc. Device abcd (rev 01) (prog-if 00 [Normal deco de])
Flags: bus master, fast devsel, latency 0
Memory at 01000000 (32-bit, non-prefetchable) [size=1M]
Bus: primary=00, secondary=01, subordinate=01, sec-latency=0
Memory behind bridge: 01100000-011fffff
[virtual] Expansion ROM at 01200000 [disabled] [size=64K]
Capabilities: [40] Power Management version 3
Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
Capabilities: [70] Express Root Port (Slot-), MSI 00
Capabilities: [100] Advanced Error Reporting
Capabilities: [140] Virtual Channel
Kernel driver in use: pcieport
01:00.0 Serial controller: Exar Corp. Device 0354 (rev 03) (prog-if 02 [16550])
Flags: fast devsel, IRQ 334
Memory at 01100000 (32-bit, non-prefetchable) [size=16K]
Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
Capabilities: [78] Power Management version 3
Capabilities: [80] Express Endpoint, MSI 01
Capabilities: [100] Virtual Channel
然而，訊息除了與 Hummingboard 相關的 GPIO 之外，沒有提及在啟動時創建的 tty，它們一直存在。
供應商（Diamond）提供了一個自訂驅動程序，我從原始程式碼下載並建立了該驅動程式。當我加載.ko,訊息說：
[ 640.564446] DSMPESER4MDriver: loading out-of-tree module taints kernel.
[ 640.565123] The init fun get called
[ 640.565199] pci 0000:01:00.0: enabling device (0140 -> 0142)
[ 640.565359] DS-MPE-SER4M driver loaded
和/var/日誌/訊息說：
root@torpedo:~# tail -f /var/log/messages
...
Apr 17 15:48:50 torpedo kernel: DSMPESER4MDriver: loading out-of-tree module taints kernel.
Apr 17 15:48:50 torpedo kernel: The init fun get called
Apr 17 15:48:50 torpedo kernel: pci 0000:01:00.0: enabling device (0140 -> 0142)
Apr 17 15:48:50 torpedo kernel: DS-MPE-SER4M driver loaded
幾個問題：
- 如何修復「載入樹外模組污染核心」？ （不是技術問題 - 請參閱評論）
- 我該如何使用姆諾德來創建/dev/tty該驅動程式的文件？
- 如何配置模組在啟動時載入？
答案1
這EXAR 文件是正確的。這個板子是現代 Linux 核心支援。對我來說，這個問題是我的核心配置為總共僅支援 4 個串行埠。
在 Hummingboard 上，片上 UART 耗盡了前 4 個 UART。我將內核重新配置為最多 16 個串行埠。重建我的內核如下Debian 特定方法。重新啟動。
root@torpedo:~# uname -a
Linux torpedo 4.16.2whoi-armhf #1 SMP Wed Apr 18 16:56:21 GMT 2018 armv7l GNU/Linux
新核心已安裝並正在運行...檢查 PCI 總線：
root@torpedo:~# lspci -vv
...
01:00.0 Serial controller: Exar Corp. Device 0354 (rev 03) (prog-if 02 [16550])
Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr+ Stepping- SERR+ FastB2B- DisINTx-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Latency: 0, Cache Line Size: 64 bytes
Interrupt: pin A routed to IRQ 334
Region 0: Memory at 01100000 (32-bit, non-prefetchable) [size=16K]
Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
Address: 0000000000000000 Data: 0000
Capabilities: [78] Power Management version 3
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0+,D1-,D2-,D3hot+,D3cold-)
Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [80] Express (v2) Endpoint, MSI 01
DevCap: MaxPayload 256 bytes, PhantFunc 0, Latency L0s <64ns, L1 <1us
ExtTag- AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
DevCtl: Report errors: Correctable- Non-Fatal- Fatal- Unsupported-
RlxdOrd+ ExtTag- PhantFunc- AuxPwr- NoSnoop+
MaxPayload 128 bytes, MaxReadReq 512 bytes
DevSta: CorrErr- UncorrErr- FatalErr- UnsuppReq- AuxPwr- TransPend-
LnkCap: Port #1, Speed 2.5GT/s, Width x1, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
ClockPM- Surprise- LLActRep- BwNot-
LnkCtl: ASPM Disabled; RCB 64 bytes Disabled- CommClk-
ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
LnkSta: Speed 2.5GT/s, Width x1, TrErr- Train- SlotClk- DLActive- BWMgmt- ABWMgmt-
DevCap2: Completion Timeout: Not Supported, TimeoutDis-, LTR-, OBFF Not Supported
DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis-, LTR-, OBFF Disabled
LnkCtl2: Target Link Speed: 2.5GT/s, EnterCompliance- SpeedDis-
Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
Compliance De-emphasis: -6dB
LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete-, EqualizationPhase1-
EqualizationPhase2-, EqualizationPhase3-, LinkEqualizationRequest-
Capabilities: [100 v1] Virtual Channel
Caps: LPEVC=0 RefClk=100ns PATEntryBits=1
Arb: Fixed- WRR32- WRR64- WRR128-
Ctrl: ArbSelect=Fixed
Status: InProgress-
VC0: Caps: PATOffset=00 MaxTimeSlots=1 RejSnoopTrans-
Arb: Fixed- WRR32- WRR64- WRR128- TWRR128- WRR256-
Ctrl: Enable+ ID=0 ArbSelect=Fixed TC/VC=ff
Status: NegoPending- InProgress-
Kernel driver in use: exar_serial
看起來我沒有破壞PCI總線。
內核是否找到了 UART？
root@torpedo:~# dmesg|grep tty
[ 0.000000] Kernel command line: root=/dev/mmcblk0p1 rootfstype=ext4 rootwait console=tty1 consoleblank=0 video=mxcfb0:dev=hdmi,1920x1080m60,if=RGB24,bpp=32 rd.dm=0 rd.luks=0 rd.lvm=0 raid=noautodetect pci=nomsi vt.global_cursor_default=0 loglevel=1
[ 0.001375] console [tty1] enabled
[ 1.220660] 0000:01:00.0: ttyS0 at MMIO 0x1100000 (irq = 334, base_baud = 7812500) is a XR17V35X
[ 1.221093] 0000:01:00.0: ttyS1 at MMIO 0x1100400 (irq = 334, base_baud = 7812500) is a XR17V35X
[ 1.221498] 0000:01:00.0: ttyS2 at MMIO 0x1100800 (irq = 334, base_baud = 7812500) is a XR17V35X
[ 1.221896] 0000:01:00.0: ttyS3 at MMIO 0x1100c00 (irq = 334, base_baud = 7812500) is a XR17V35X
[ 1.222587] 2020000.serial: ttymxc0 at MMIO 0x2020000 (irq = 26, base_baud = 5000000) is a IMX
[ 1.223350] 21ec000.serial: ttymxc2 at MMIO 0x21ec000 (irq = 70, base_baud = 5000000) is a IMX
[ 1.224122] 21f0000.serial: ttymxc3 at MMIO 0x21f0000 (irq = 71, base_baud = 5000000) is a IMX
涼爽的。作品。