Impact: doc simple using howto for earlyprintk=dbgp Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx> --- Documentation/x86/earlyprintk.txt | 41 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+) Index: linux-2.6/Documentation/x86/earlyprintk.txt =================================================================== --- /dev/null +++ linux-2.6/Documentation/x86/earlyprintk.txt @@ -0,0 +1,41 @@ + +Using earlyprintk with USB2 Debug port and debug cable + +1. HW: +a. target system need to have debug port + +# lspci -vvv +... +00:1d.7 USB Controller: Intel Corporation 82801H (ICH8 Family) USB2 EHCI Controller #1 (rev 03) (prog-if 20 [EHCI]) + Subsystem: Lenovo ThinkPad T61 + Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx- + Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx- + Latency: 0 + Interrupt: pin D routed to IRQ 19 + Region 0: Memory at fe227000 (32-bit, non-prefetchable) [size=1K] + Capabilities: [50] Power Management version 2 + Flags: PMEClk- DSI- D1- D2- AuxCurrent=375mA PME(D0+,D1-,D2-,D3hot+,D3cold+) + Status: D0 PME-Enable- DSel=0 DScale=0 PME+ + Capabilities: [58] Debug port: BAR=1 offset=00a0 + Kernel driver in use: ehci_hcd + Kernel modules: ehci-hcd +... +b. netchip USB debug cable + http://www.plxtech.com/products/NET2000/NET20DC/default.asp + +c. console system: have USB2 port + +2. SW setting +a. console system: need to have kernel config + CONFIG_USB_SERIAL_DEBUG + you should get /dev/ttyUSBx + + # cat /dev/ttyUSBx could get output + +b. target system: need to have kernel config + CONFIG_EARLY_PRINTK_DBGP + + boot command line: earlyprintk=dbgp + +c. for Nvidia Southbridge based system: kernel will try to probe and find out which port has debug device connneted. + -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
