Radical idea for X-modmap problem.
David Moffatt
David.Moffatt at access-company.com
Sun Jul 26 12:06:41 PDT 2009
Responding to the thread about mapping hardware scan codes --> X key
codes and keyboards with > 248 keys.
Perhaps the solution is to take the hardware scan code --> Symbol
problem out of the X layer entirely. Let the OS deal with that in its
own manner.
Simpler is better?
(Please flame/reply to me in private david.moffatt at access-company.com)
-----Original Message-----
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Today's Topics:
1. Re: Kernel 2.6.30.1 Oops on Alpha Architecture when starting
Xserver (Dave Airlie)
2. Re: XI2 = moving target? (Jim Gettys)
3. Re: XI2 = moving target? (Alan Cox)
4. Re: XI2 = moving target? (Jim Gettys)
5. Re: XI2 = moving target? (Peter Hutterer)
6. Re: XI2 = moving target? (Maxim Levitsky)
7. Re: XI2 = moving target? (Nicolas Mailhot)
8. Re: XI2 = moving target? (Peter Hutterer)
9. Re: XI2 = moving target? (Maxim Levitsky)
----------------------------------------------------------------------
Message: 1
Date: Sun, 26 Jul 2009 08:54:27 +1000
From: Dave Airlie <airlied at gmail.com>
Subject: Re: Kernel 2.6.30.1 Oops on Alpha Architecture when starting
Xserver
To: Michael Cree <mcree at orcon.net.nz>
Cc: xorg at lists.freedesktop.org, linux-kernel at vger.kernel.org,
linux-alpha at vger.kernel.org
Message-ID:
<21d7e9970907251554m18e4fca5p69b758e36fddc7d9 at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
>>> The kernel oops is:
>>>
>>
>> So its a machine check,
>>
>
> So, does this indicate a software fault (e.g. inconsistencies in
kernel data
> structures) or does it imply a hardware fault?
>
>> Well X is trying to post the graphics card you have installed, and
the
>> machine
>> is falling over when it does it.
>>
>
> SRM (the equivalent of a BIOS) cannot post the card on startup. ?But I
have
> had the card (radeon rv610) post correctly and working in the past
when I
> compiled the complete 1.5.3 Xserver myself. ?I had it working with
both the
> radeon and radeonhd drivers and a 2.6.29.x kernel patched to support
> libpciaccess.
There is no -ati card in that machine, its got some SiS card which is
completely
different, maybe its some onboard card or something.
Dave.
------------------------------
Message: 2
Date: Sat, 25 Jul 2009 19:30:20 -0400
From: Jim Gettys <jg at freedesktop.org>
Subject: Re: XI2 = moving target?
To: Nicolas Mailhot <nicolas.mailhot at laposte.net>
Cc: "Timothy S. Nelson" <wayland at wayland.id.au>,
xorg at lists.freedesktop.org
Message-ID: <4A6B958C.9040905 at freedesktop.org>
Content-Type: text/plain; charset=UTF-8; format=flowed
Nicolas,
In the original X11 design and keyboard system, keycodes are arbitrary,
and need not have anything to do with the codes produced by the hardware
(which are often quite baroque, and often formed by multiple character
transmissions from the keyboard to the host).
Just because the hardware sends some byte, doesn't mean it needs to be
used as its keycode. It is often convenient to do so, but not
necessary... And they may have nothing to do with PS/2 keyboards at
all; in fact, most workstation keyboards were entirely different.
For example, some keyboards (at the hardware level) have sent a bit
vector of all the keys that are down as a set of bytes, and that has
then been translated to a sequence of keycodes that changed. Others
transmit a few bytes that talk about X/Y coordinates in the scan matrix,
and whether the key went up or down.
There may be something in our current implementations that deal with PC
style keyboards that do magic with keycodes > 255 and translate them,
but that is different than what gets encoded into a keyboard event as a
keycode.
Usually, when one is trying to distinguish what the hardware sends from
the X protocol layer (or if you actually talk about what keyboards
send), the bytes a keyboard transmits are called "scancodes". It has
been convenient on many keyboards to just use them as keycodes if the
keyboard makes it easy, but not necessary.
Ergo my question on whether anyone has ever actually seen in captivity a
keyboard with more than 248 keys...
- Jim
Nicolas Mailhot wrote:
> Le samedi 25 juillet 2009 ? 13:31 -0400, Jim Gettys a ?crit :
>> That isn't a good reason: keycodes are arbitrary, a simple table
lookup
>> to remap them to 8-255 is an easy solution, much easier than the
>> alternatives, unless I'm missing something...
>
> keycodes are not arbitrary, the codes > 255 have a standardised
meaning,
> if you remap them they don't behave like they should according to the
> symbol printed on them.
>
> Also it is very common to have multiple input devices nowadays that
all
> have some keycodes > 255 so any remapping solution would need to be
able
> to manage parallel hotplug of devices with different requirements (in
> fact what is un-common is devices that only use keycodes < 255, I
tried
> to buy one last time I was in the local chinatown to avoid dealing
with
> this issue ? they don't exist anymore)
>
------------------------------
Message: 3
Date: Sun, 26 Jul 2009 00:44:50 +0100
From: Alan Cox <alan at lxorguk.ukuu.org.uk>
Subject: Re: XI2 = moving target?
To: Jim Gettys <jg at freedesktop.org>
Cc: "Timothy S. Nelson" <wayland at wayland.id.au>,
xorg at lists.freedesktop.org, Nicolas Mailhot
<nicolas.mailhot at laposte.net>
Message-ID: <20090726004450.31580dcc at lxorguk.ukuu.org.uk>
Content-Type: text/plain; charset=US-ASCII
> Ergo my question on whether anyone has ever actually seen in captivity
a
> keyboard with more than 248 keys...
I'm not sure that is a useful question.
I have a collection of keyboards and remotes. All of them have different
functions above 255 which could be remapped. All of them are hot
pluggable.
Trying to manage a mapping of all the devices randomly on the fly
plugged
into a system and map them into a tiny space is rather more difficult
than you make out.
If you had to map a set of devices, once, to a fixed mapping it wouldn't
be a big deal, but the world has moved on from that.
Alan
------------------------------
Message: 4
Date: Sat, 25 Jul 2009 20:29:40 -0400
From: Jim Gettys <jg at freedesktop.org>
Subject: Re: XI2 = moving target?
To: Alan Cox <alan at lxorguk.ukuu.org.uk>
Cc: "Timothy S. Nelson" <wayland at wayland.id.au>,
xorg at lists.freedesktop.org, Nicolas Mailhot
<nicolas.mailhot at laposte.net>
Message-ID: <4A6BA374.8090407 at freedesktop.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I guess I'm still confused...
So they'd show up as different devices with time; each time you get
notification that the keysym mapping for the keycodes have changed.
Why is there a problem?
- Jim
Alan Cox wrote:
>> Ergo my question on whether anyone has ever actually seen in
captivity a
>> keyboard with more than 248 keys...
>
> I'm not sure that is a useful question.
>
> I have a collection of keyboards and remotes. All of them have
different
> functions above 255 which could be remapped. All of them are hot
> pluggable.
>
> Trying to manage a mapping of all the devices randomly on the fly
plugged
> into a system and map them into a tiny space is rather more difficult
> than you make out.
>
> If you had to map a set of devices, once, to a fixed mapping it
wouldn't
> be a big deal, but the world has moved on from that.
>
> Alan
>
>
>
------------------------------
Message: 5
Date: Sun, 26 Jul 2009 10:37:27 +1000
From: Peter Hutterer <peter.hutterer at who-t.net>
Subject: Re: XI2 = moving target?
To: Maxim Levitsky <maximlevitsky at gmail.com>
Cc: "Timothy S. Nelson" <wayland at wayland.id.au>,
xorg at lists.freedesktop.org
Message-ID: <20090726003726.GA6793 at who-t.net>
Content-Type: text/plain; charset=us-ascii
On Sat, Jul 25, 2009 at 07:59:54PM +0300, Maxim Levitsky wrote:
> On Sat, 2009-07-25 at 12:12 -0400, Jim Gettys wrote:
> > For curiosity's sake, have people actually seen keyboards with more
than
> > 248 keys?
>
> No, but plenty with keycodes > 256
> (Most TV remotes fail in this category, and I still am waiting for
limit
> of 256 keycodes to be lifted)
keycodes are 32 bit in XI2, though to get full support for that we also
need
XKB2. Right now, we still cap at keycodes > 255. this is an
implementation
issue though, not a protocol restriction.
Cheers,
Peter
------------------------------
Message: 6
Date: Sun, 26 Jul 2009 04:11:00 +0300
From: Maxim Levitsky <maximlevitsky at gmail.com>
Subject: Re: XI2 = moving target?
To: Peter Hutterer <peter.hutterer at who-t.net>
Cc: "Timothy S. Nelson" <wayland at wayland.id.au>,
xorg at lists.freedesktop.org
Message-ID: <1248570660.6786.2.camel at maxim-laptop>
Content-Type: text/plain
On Sun, 2009-07-26 at 10:37 +1000, Peter Hutterer wrote:
> On Sat, Jul 25, 2009 at 07:59:54PM +0300, Maxim Levitsky wrote:
> > On Sat, 2009-07-25 at 12:12 -0400, Jim Gettys wrote:
> > > For curiosity's sake, have people actually seen keyboards with
more than
> > > 248 keys?
> >
> > No, but plenty with keycodes > 256
> > (Most TV remotes fail in this category, and I still am waiting for
limit
> > of 256 keycodes to be lifted)
>
> keycodes are 32 bit in XI2, though to get full support for that we
also need
> XKB2. Right now, we still cap at keycodes > 255. this is an
implementation
> issue though, not a protocol restriction.
>
> Cheers,
> Peter
Nice, and while at it, I have few questions:
1) will XKB2 allow 32 bit scancodes transparently for all Xlib
applicatuions, or at least for all Qt/GTK applications with small
modifications
2) When this will happen?
Best regards
Maxim Levitsky
------------------------------
Message: 7
Date: Sun, 26 Jul 2009 07:06:43 +0200
From: Nicolas Mailhot <nicolas.mailhot at laposte.net>
Subject: Re: XI2 = moving target?
To: Jim Gettys <jg at freedesktop.org>
Cc: "Timothy S. Nelson" <wayland at wayland.id.au>,
xorg at lists.freedesktop.org
Message-ID: <1248584803.25858.4.camel at arekh.okg>
Content-Type: text/plain; charset="utf-8"
Le samedi 25 juillet 2009 ? 19:30 -0400, Jim Gettys a ?crit :
> Nicolas,
>
> In the original X11 design and keyboard system, keycodes are
arbitrary,
> and need not have anything to do with the codes produced by the
hardware
> (which are often quite baroque, and often formed by multiple character
> transmissions from the keyboard to the host).
Modern scan codes are not arbitrary and when there are quirks they are
hidden by the kernel input layer so right now xorg needs to talk to
devices that use all the same keycodes (with many > 255).
--
Nicolas Mailhot
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Message: 8
Date: Sun, 26 Jul 2009 18:41:37 +1000
From: Peter Hutterer <peter.hutterer at who-t.net>
Subject: Re: XI2 = moving target?
To: Jim Gettys <jg at freedesktop.org>
Cc: "Timothy S. Nelson" <wayland at wayland.id.au>, Nicolas Mailhot
<nicolas.mailhot at laposte.net>, xorg at lists.freedesktop.org
Message-ID: <20090726084136.GA6954 at who-t.net>
Content-Type: text/plain; charset=us-ascii
On Sat, Jul 25, 2009 at 08:29:40PM -0400, Jim Gettys wrote:
> I guess I'm still confused...
>
> So they'd show up as different devices with time; each time you get
> notification that the keysym mapping for the keycodes have changed.
>
> Why is there a problem?
It makes things overly complicated.
We use a number of shortcuts to simplify the keycode handling. One is
that
we don't actually use the keycode range as an actual range but rather
use
the keycodes in a way similar to keysyms. If you're using the evdev
driver,
each keycode is already defined to a specific symbol with
hardware-specific
quirks being done in the kernel or in HAL (possibly udev now, I still
haven't looked into that).
You could free the keycodes completely but then you'd have to have a
Kcgst
mapping for xkeyboard-config for every single device. Which means that
the
maintainance of xkeyboard-config becomes a nightmare, together with the
myriads of things that can go wrong when users select the wrong keyboard
model.
By having a standardised set of keycodes this becomes much easier.
In fact these days it is irrelevant what you select as your keyboard
model
in the evdev ruleset - they all map to the evdev model (there are a few
exceptions that do require separate models). So the XKB configuration
mostly
deals with the actual layouts, taking one layer of complexity out.
You could treat the keycode range as intended in the original X
protocol,
but then you'd have to have a model for every keyboard, remote, magic
other
device ever manufactured. We sort-of do that (look at the xorg/xfree86
ruleset) but it's not pretty.
So by upping the keycode range to 32 bits we enable a larger
standardised
set of keycodes without the nightmare of maintaining loads of different
keyboard models and requiring the user to configure them correctly.
Note that a keycode still doesn't stand for a symbol. KEY_Q is still an
'a'
if you have an azerty group.
Cheers,
Peter
> Alan Cox wrote:
> >> Ergo my question on whether anyone has ever actually seen in
captivity a
> >> keyboard with more than 248 keys...
> >
> > I'm not sure that is a useful question.
> >
> > I have a collection of keyboards and remotes. All of them have
different
> > functions above 255 which could be remapped. All of them are hot
> > pluggable.
> >
> > Trying to manage a mapping of all the devices randomly on the fly
plugged
> > into a system and map them into a tiny space is rather more
difficult
> > than you make out.
> >
> > If you had to map a set of devices, once, to a fixed mapping it
wouldn't
> > be a big deal, but the world has moved on from that.
> >
> > Alan
------------------------------
Message: 9
Date: Sun, 26 Jul 2009 13:20:53 +0300
From: Maxim Levitsky <maximlevitsky at gmail.com>
Subject: Re: XI2 = moving target?
To: Peter Hutterer <peter.hutterer at who-t.net>
Cc: "Timothy S. Nelson" <wayland at wayland.id.au>,
xorg at lists.freedesktop.org, Nicolas Mailhot
<nicolas.mailhot at laposte.net>
Message-ID: <1248603653.6285.5.camel at maxim-laptop>
Content-Type: text/plain
On Sun, 2009-07-26 at 18:41 +1000, Peter Hutterer wrote:
> On Sat, Jul 25, 2009 at 08:29:40PM -0400, Jim Gettys wrote:
> > I guess I'm still confused...
> >
> > So they'd show up as different devices with time; each time you get
> > notification that the keysym mapping for the keycodes have changed.
> >
> > Why is there a problem?
>
> It makes things overly complicated.
And besides, this even doesn't work.
The older keyboard driver will read from underlying tty, while putting
it in raw mode. It actually assumes it always talks to standard PC
keyboard controller, (and kernel emulates it)
And newer evdev will pass keycodes as is to X, thus only way around
today is to make kernel driver remap the keycodes, and not all kernel
drivers support this, and there is no standard way to set such.
So, when we see 32 keycodes?
Best regards,
Maxim Levitsky
>
> We use a number of shortcuts to simplify the keycode handling. One is
that
> we don't actually use the keycode range as an actual range but rather
use
> the keycodes in a way similar to keysyms. If you're using the evdev
driver,
> each keycode is already defined to a specific symbol with
hardware-specific
> quirks being done in the kernel or in HAL (possibly udev now, I still
> haven't looked into that).
>
> You could free the keycodes completely but then you'd have to have a
Kcgst
> mapping for xkeyboard-config for every single device. Which means that
the
> maintainance of xkeyboard-config becomes a nightmare, together with
the
> myriads of things that can go wrong when users select the wrong
keyboard
> model.
>
> By having a standardised set of keycodes this becomes much easier.
> In fact these days it is irrelevant what you select as your keyboard
model
> in the evdev ruleset - they all map to the evdev model (there are a
few
> exceptions that do require separate models). So the XKB configuration
mostly
> deals with the actual layouts, taking one layer of complexity out.
>
> You could treat the keycode range as intended in the original X
protocol,
> but then you'd have to have a model for every keyboard, remote, magic
other
> device ever manufactured. We sort-of do that (look at the xorg/xfree86
> ruleset) but it's not pretty.
>
> So by upping the keycode range to 32 bits we enable a larger
standardised
> set of keycodes without the nightmare of maintaining loads of
different
> keyboard models and requiring the user to configure them correctly.
>
> Note that a keycode still doesn't stand for a symbol. KEY_Q is still
an 'a'
> if you have an azerty group.
>
> Cheers,
> Peter
>
> > Alan Cox wrote:
> > >> Ergo my question on whether anyone has ever actually seen in
captivity a
> > >> keyboard with more than 248 keys...
> > >
> > > I'm not sure that is a useful question.
> > >
> > > I have a collection of keyboards and remotes. All of them have
different
> > > functions above 255 which could be remapped. All of them are hot
> > > pluggable.
> > >
> > > Trying to manage a mapping of all the devices randomly on the fly
plugged
> > > into a system and map them into a tiny space is rather more
difficult
> > > than you make out.
> > >
> > > If you had to map a set of devices, once, to a fixed mapping it
wouldn't
> > > be a big deal, but the world has moved on from that.
> > >
> > > Alan
>
> _______________________________________________
> xorg mailing list
> xorg at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/xorg
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