Messages in this thread | | | Date | Wed, 20 Aug 2003 09:14:39 -0700 | From | Greg KH <> | Subject | Re: Console on USB |
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On Tue, Aug 19, 2003 at 10:20:51PM -0500, Thomas Molina wrote: > I have just spent a very frustrating evening trying to get console on USB > working. My laptop does not have regular DB-9 serial connectors, only > USB. So I ordered a USB to serial converter,
Which usb to serial converter? Not all of them work with Linux. Does this device work with Linux _not_ as a serial console device?
> configured a 2.6.0-test3 > kernel, added a console=/dev/ttyUSB0 to the kernel command line and > connected this to my desktop with a null modem adapter. However, I am > unable to get output from this setup on the desktop. On another setup I > can get a normal serial console output, so I am fairly confident I can set > things up correctly.
Which "serial console" are you trying to get working? The kernel log console, or a login console?
> Googling around and doing a search on lkml archives gave some minimal > help, but I can find very little info past early to mid 2.5 kernels. The > configuration doesn't quite seem to work the way I read documentation. > For instance, the web pages I can find indicate I should be able to build > this modular; however the configuration makes the setting of console on > usb depend on USB being y and EXPERIMENTAL being defined.
What web page says you can build this modular? You have to build it into the kernel.
> In /var/log/messages I can see the USB-to-serial converter being recogized > and the driver being loaded, just before the synaptics touchpad is probed.
Can you show us the relevant part of the kernel logs?
> It looks like things are correct, but, as I said, I am unable to get > output. Am I headed for frustration, or is there some advice to get good > results?
You are headed for frustration. USB serial console was a neat hack, but pretty pointless. It has the following problems: - can't see oopses before USB starts up, and USB starts up almost last in the system boot process. - really can not capture oopses very well as USB is interrupt driven - most usb-serial converters have a very small buffer, so you constantly get over-runs in printing out console messages (meaning that only a few of the devices will even work properly, you usually have to buy one of the expensive ones to see all messages.)
> Is there any advice I might be able to use to get this going? I really > want to be able to catch some oops output.
Buy a machine with a serial port. That's my recommendation :)
Good luck,
greg k-h - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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