On Wed, Feb 21, 2007 at 10:58:54AM +0100, Tomasz Chmielewski wrote: > So far, I've been using a normal serial console with a device running Linux. > I configured it in two places: > - kernel command line to see kernel messages: console=ttyS0,115200 > - /etc/inittab: T0:23:respawn:/sbin/getty -L ttyS0 115200 vt102 (to be > able to log in) > > > As to use that serial console I have to open the device, I decided I > will use a USB-serial console instead. The changes seemed trivial: > > - compile all USB/console related stuff in the kernel > - kernel command line to see kernel messages: console=ttyUSB0,115200 > - /etc/inittab: T0:23:respawn:/sbin/getty -L ttyUSB0 115200 vt102 > > > However, this doesn't work as I expected: > > 1) I don't see any "initial" kernel messages on the USB-serial console: > > Linux version 2.6.20 ([EMAIL PROTECTED]) (gcc version 4.1.1) #56 PREEMPT Tue > Feb 20 18:14:38 CET 2007 > CPU: XScale-IXP42x Family [690541f1] revision 1 (ARMv5TE), cr=0000397f > Machine: Freecom FSG-3 > (...) > > I guess that's because kernel didn't initialize USB-subsystem yet? > > > 2) After loading the kernel, my system is set up to wait for 10 seconds > before continuing and loading the proper "init". 10 seconds should be > far more than necessary for the system to see all USB devices? > Still, when the system loads, I don't see any kernel messages, system > loading etc. on ttyUSB0 (I saw these things with console=ttyS0,115200). > > > 3) As soon as the system loads completely, I get a login prompt on > ttyUSB0 (started by getty). From this point on, I will get kernel > messages onto ttyUSB0. > > > Why do I get kernel messages logged on the USB-serial console that late, > only after the system is fully loaded and after I get a login prompt on > ttyUSB0?
Because that is when the USB serial port is finally found by the kernel. I wouldn't use usb serial devices for console devices to see the kernel logs, due to the lateness of discovery and the need for interrupts to work properly (so it will not show crash dumps.) But for just "normal" logins, it should work fine. good luck, greg k-h ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Linux-usb-users@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-users
