kern/104675: Apparently there is a clash between two ioctls

[Bruce Evans]

On Sun, 22 Oct 2006, Jukka A. Ukkonen wrote:

>> Description:
> 	It seems that the bktr driver cannot change the input connector
> 	used when using a card with multiple connectors.
> 	When I used ktrace to see what happens at the kernel API level
> 	I got somewhat disturbing output...
>
> 56314 try      CALL  ioctl(0x3,METEORGINPUT,0xbfbfed24)
> 56314 try      RET   ioctl 0
> 56314 try      CALL  ioctl(0x3,SERIAL_SETINVCLK,0xbfbfed20)
> 56314 try      RET   ioctl 0
> 56314 try      CALL  ioctl(0x3,METEORGINPUT,0xbfbfed20)
> 56314 try      RET   ioctl 0
>
>      It seems that METEORGINPUT is recognized properly but its
>      complement METEORSINPUT is not. Instead METEORSINPUT gets
>      mapped to something completely unrelated (SERIAL_SETINVCLK).

This is probably not the real problem.  There are too many ambiguous
ioctls for kdump to fix, so kdump carefully avoids seeing the problem
by not invoking mkioctls with -s.  But this is only a debugging problem.
The ioctl numbers are unique for each device, so device drivers have
no problems with their ambiguity.  To do the same for just the above,
kdump would have to determine that fd 0x3 is for bktr and use bktr's
ioctl switch statement instead of Cronyx serial's one.  It now just
uses an elseif ladder that has all the ioctls but only finds the
first match.

Bruce