AllowEmptyInput and HAL

[Phil Endecott]

Phil Endecott wrote:
> Daniel Stone wrote:
>> Hi,
>>
>> On Tue, Apr 28, 2009 at 10:01:25PM +0100, Phil Endecott wrote:

>>> I have a keyboard 
>>> where every alternate keystroke produces the right letter and the 
>>> others produce garbage (maybe top-bit-set characters?).
>>
>> Cool.  Could you please send xev output?
>
> Unfortunately this is hard as I cannot log in.  Presumably there is 
> some way in which I can bypass xdm and cause X to start running and 
> then start xev from another machine, or something.  I'll investigate.

I started x using startx and I can now retype the following xev 
output.  This is for press-release-press-release of the A key.  The 
pattern then repeats and seems to be consistent with other keys:

KeyPress event, serial 27, synthetic NO, window 0xa00001,
     root 0x3e, subw 0, time 7372197, (78,77), root:(699,464),
     state 0x5, keycode 38 (keysym 0x41, A), same_screen YES,
     XLookupString gives 1 bytes: (01) ""
     XmbLookupString gives 1 bytes: (01) ""
     XFilterEvent returns: False

KeyRelease event, serial 27, synthetic NO, window 0xa00001,
     root 0x3e, subw 0, time 7372293, (78,77), root:(699,464),
     state 0x5, keycode 38 (keysym 0x41, A), same_screen YES,
     XLookupString gives 1 bytes: (01) ""

KeyPress event, serial 27, synthetic NO, window 0xa00001,
     root 0x3e, subw 0, time 7372549, (78,77), root:(699,464),
     state 0x0, keycode 38 (keysym 0x61, a), same_screen YES,
     XLookupString gives 1 bytes: (61) "a"
     XmbLookupString gives 1 bytes: (61) "a"
     XFilterEvent returns: False

KeyRelease event, serial 27, synthetic NO, window 0xa00001,
     root 0x3e, subw 0, time 7372621, (78,77), root:(699,464),
     state 0x5, keycode 38 (keysym 0x41, A), same_screen YES,
     XLookupString gives 1 bytes: (01) ""

I then ran strace on X and looked at what it read from 
/dev/input/event1 while I did the same thing.  Deciphering using 
/usr/include/linux/input.h I see

MSC SCAN 0407
KEY A DOWN
SYN

MSC SCAN 0407
KEY A UP
SYN

MSC SCAN 0407
KEY A DOWN
SYN

MSC SCAN 0407
KEY A UP
SYN

i.e. nothing unusual (I haven't seen the 'scan' stuff before, but I 
presume that X has done an ioctl to ask for it or something.)

Perhaps these events are being misinterpretted in the wrong format, or 
something.  But in that case I would have expected the symptom to be 
recognised by someone.


Phil.