Re: better console support

[Keir Fraser <keir@xensource.com>]

On 26/1/07 12:58 am, "Edward Pilatowicz" <edward.pilatowicz@sun.com> wrote:

> so does xen have any uses for serial ports other than as a console
> device?  if not then we can probably use this to detect an in use
> port and switch the console to use hypervisor interfaces in this case.

You could set up a remote debug session, but that's not really a normal
usage.

> well, i don't think the xen vgakeep mode (which is essentially an
> extension of the default vga mode) really provides us with a usable
> console configuration since xen doesn't support any kind of keyboard
> input.  (at least from my reading of the 3.0.3 code i think will only
> take input from a serial port.)  so setting the xen to vga and vgakeep
> and then setting the dom0 console to the hypervisor would essentially
> give you a read-only console.

Our observation has been that, as long as Linux keeps the console in text
mode (doesn't switch to X for example) we can let Linux think it owns the
VGA console and things don't screw up if Xen continues to have at it also.
Again, this isn't really something we'd consider as a normal usage scenario
-- more something to try if Xen doesn't boot and you can't connect a serial
line for some reason.

Xen doesn't include a full debugger -- it has a serial gdbstub which does
its job quite nicely -- so there's nothing really to plumb keyboard input
into. The set of 'debug keys' we plan to make accessible via the xm tool.

 -- Keir