Re: debugging a modern laptop ...
From: Alan Stern
Date: Wed Mar 23 2011 - 11:04:53 EST
On Wed, 23 Mar 2011, Herbert Poetzl wrote:
> I'm trying to evaluate my options on debugging a recent
> laptop/notebook/table (and the Linux kernel on it of course)
> from early bootup to diagnostics when the machine has locked
> up ...
> normally the first thing I would do is to attach a serial
> console to monitor the early bootup and have some way to
> send sysrq triggers ... but here is the first problem,
> the thing might not even have a serial port at all ...
> most modern devices have at least one usb port, but as far
> as I could figure out via google, there is no support for
> console or similar over usb (serial or not) atm
> (please feel free to correct me here :)
There _is_ support for a USB console (see CONFIG_USB_SERIAL_CONSOLE).
However it may not be useful for diagnosing problems during boot,
because obviously the console won't operate until the USB stack is in
place and running.
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