linux-kernel - Re: [PATCH] i8042: Add debug

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Message-ID: <20150625213511.GB27620@dtor-ws>
Date:	Thu, 25 Jun 2015 14:35:11 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Stephen Chandler Paul <cpaul@...hat.com>
Cc:	Benjamin Tissoires <benjamin.tissoires@...hat.com>,
	linux-kernel@...r.kernel.org, linux-input@...r.kernel.org,
	Hans de Goede <hdegoede@...hat.com>
Subject: Re: [PATCH] i8042: Add debug_kbd option

On Thu, Jun 25, 2015 at 05:31:25PM -0400, Stephen Chandler Paul wrote:
> On Thu, 2015-06-25 at 13:32 -0700, Dmitry Torokhov wrote:
> > On Thu, Jun 25, 2015 at 03:25:10PM -0400, cpaul@...hat.com wrote:
> > > From: Stephen Chandler Paul <cpaul@...hat.com>
> > > 
> > > A big problem with the current i8042 debugging option is that it 
> > > outputs
> > > data going to and from the keyboard by default. As a result, many 
> > > dmesg
> > > logs uploaded by users will unintentionally contain sensitive 
> > > information
> > > such as their password, as such it's probably a good idea not to 
> > > output
> > > data coming from the keyboard unless specifically enabled by the 
> > > user.
> > > 
> > > Signed-off-by: Stephen Chandler Paul <cpaul@...hat.com>
> > > Reviewed-by: Benjamin Tissoires <benjamin.tissoires@...hat.com>
> > > ---
> > >  Documentation/kernel-parameters.txt |  7 +++++++
> > >  drivers/input/serio/i8042.c         | 25 +++++++++++++++++++++----
> > >  2 files changed, 28 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/Documentation/kernel-parameters.txt 
> > > b/Documentation/kernel-parameters.txt
> > > index ae44749..9e00234 100644
> > > --- a/Documentation/kernel-parameters.txt
> > > +++ b/Documentation/kernel-parameters.txt
> > > @@ -1304,6 +1304,13 @@ bytes respectively. Such letter suffixes can 
> > > also be entirely omitted.
> > >  			     <bus_id>,<clkrate>
> > >  
> > >  	i8042.debug	[HW] Toggle i8042 debug mode
> > > +	i8042.debug_kbd [HW] Enable printing of interrupt data 
> > > from the KBD port
> > > +			     As a side effect, this option will 
> > > mask some of the
> > > +			     interrupts sent back from the 
> > > keyboard during the
> > > +			     initialization of the KBD port on the 
> > > i8042, if you
> > > +			     need to see this, you will need to 
> > > enable this
> > > +			     option.
> > 
> > Hmm, can we maybe use the bus notifier and react to
> > BUS_NOTIFY_BOUND_DRIVER/BUS_NOTIFY_UNBIND_DRIVER to decide if we want 
> > to
> > see keyboard data stream?
> Out of curiosity, are there devices that aren't keyboards that actually
> make use of the KBD port? It was my understanding keyboards used the
> KBD port, and everything else uses the AUX port.

On desktops if you plug keyboard into mouse port and mouse into keyboard
port there is a chance they will work (depends on the BIOS). But I was
not talking about supporting that  necessarily, but use bus notifiers to
allow seeing KBC port stream until the driver is fully bound and when it
is to be unbound from the KBC port (whatever driver that might be).

Thanks.

-- 
Dmitry
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