[haiku-development] Re: USB Keyboard and Debugger
- From: "Michael Lotz" <mmlr@xxxxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Wed, 11 Feb 2009 21:07:52
> Hi David,
>
> David McPaul wrote:
> > Is there any way to keep the USB keyboard working when we drop to
> > the debugger.
> >
> > I get a PANIC: Double Fault a lot on the Eee PC but the keyboard
> > does
> > not work so I cannot trace it back
> I think the only way to do that is for the kernel debugger to try and
> switch USB Legacy Mode back on before entering KDL. I'm not sure how
> easy that would be to implement though.
The problem is that this cannot really be done. For EHCI it would in
principle be doable to hand the controller back to system software, but
UHCI does not provide provisions for that. Since keyboards are full/
lowspeed devices they do use UHCI however. The problem is that the BIOS
would have to re-initialize the controller and provide the legacy
emulation again. You can't simply turn it back on, as you completely
kill the legacy state the controller is in when taking over ownership
and reinitializging it. The only way you could get by would be to
completely disable OS support for USB (i.e. removing all USB host
controller drivers) so that the system always runs in legacy emulation.
Regards
Michael
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