Emulation of Linux V4L ioctls

[J.R. Oldroyd]

On Tue, 24 Nov 2009 09:11:51 +0100, Alexander Leidinger <Alexander at leidinger.net> wrote:
>
> Quoting "J.R. Oldroyd" <fbsd at opal.com> (from Mon, 23 Nov 2009 12:54:03 -0500):
> 
> > My test app is the net/skype port which installs:
> > /usr/local/share/skype/skype: ELF 32-bit LSB executable, Intel  
> > 80386, version 1 (GNU/Linux), dynamically linked (uses shared libs),  
> > for GNU/Linux 2.4.1, stripped
> >
> > I am running this on an amd64 with the code using the same
> > videodev.h.  The video is working.  Ergo, the structures appear
> > to be compatible.
> 
> Your "appear" is the right word. Licensing issues aside (I try to get  
> someone to have a look at it), I would import the code as is because  
> of this and try to fix possible edge cases afterwards. The point is,  
> we do not really know how much of the structure is used. It may be the  
> case that the structure is partly compatible (and skype only uses this  
> part), or compatible by accident (automatic padding by the compiler).  
> With the right program (printing total size, ofsset of members, and  
> size of memebers), you can detect both and take appropriate action.
> 
> Bye,
> Alexander.
> 

OK, I have placed such a program together with its output on
an amd64 and i386 here:
    http://opal.com/freebsd/sys/compat/linux/linux_vidsize.c
    http://opal.com/freebsd/sys/compat/linux/linux_vidsize_out.amd64
    http://opal.com/freebsd/sys/compat/linux/linux_vidsize_out.i386

There are differences in sizes in the following:
	video_tuner	unsigned long rangelow
	video_tuner	unsigned long rangehigh
	video_window	struct video_clip * clips
	video_buffer	void * base
	video_code	__u8 * data
All are 8 bytes on the amd64 and 4 bytes on the i386.

	-jr
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