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From: John Baldwin <jhb@freebsd.org>
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Cc: usb@freebsd.org, Alfred Perlstein <alfred@freebsd.org>,
	Andrew Thompson <thompsa@freebsd.org>,
	Hans Petter Selasky <hselasky@c2i.net>
Subject: Re: USB polling (75% done)
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On Tuesday 21 July 2009 8:20:32 am Hans Petter Selasky wrote:
> On Monday 20 July 2009 23:51:41 Alfred Perlstein wrote:
> > * Hans Petter Selasky <hselasky@c2i.net> [090715 13:37] wrote:
> > > Hi,
> > >
> > > I've added minimal polling support to the USB P4 repository now. Patch
> > > can be found here:
> > >
> > > http://perforce.freebsd.org/chv.cgi?CH=166148
> > >
> > > Dumping core to USB disk: Tested and works.
> > >
> > > Using USB keyboard in KDB: Does not work because Giant is not locked 
when
> > > calling into the UKBD's get char routine. UKBD is Giant locked. Someone
> > > familiar with the keyboard system on FreeBSD please step forward and fix
> > > this so that UKBD gets independent of the Giant mutex.
> >
> > the ukbd driver needs giant?
> 
> I think the keyboard mux is under Giant, and does not have any concept about 
> mutexes. Most simple solution would be that DDB locks Giant before entering 
> into the keyboard code.

In general if you are in DDB you should not be using any locks at all.

-- 
John Baldwin