Date: Tue, 24 Nov 2009 11:22:20 -0500 From: "J.R. Oldroyd" <fbsd@opal.com> To: Alexander Leidinger <Alexander@leidinger.net> Cc: freebsd-emulation@freebsd.org Subject: Re: Emulation of Linux V4L ioctls Message-ID: <20091124112220.6b4b742f@shibato.opal.com> In-Reply-To: <20091124091151.12733pwkk9ha1yyo@webmail.leidinger.net> References: <20091119153159.610debc2@shibato.opal.com> <20091120103535.815072bwgvis0io0@webmail.leidinger.net> <20091120103622.0db845c8@shibato.opal.com> <20091123144251.11055vw9sv236voc@webmail.leidinger.net> <20091123125403.20e3a63e@shibato.opal.com> <20091124091151.12733pwkk9ha1yyo@webmail.leidinger.net>
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On Tue, 24 Nov 2009 09:11:51 +0100, Alexander Leidinger <Alexander@leidinge=
r.net> wrote:
>
> Quoting "J.R. Oldroyd" <fbsd@opal.com> (from Mon, 23 Nov 2009 12:54:03 -0=
500):
>=20
> > My test app is the net/skype port which installs:
> > /usr/local/share/skype/skype: ELF 32-bit LSB executable, Intel =20
> > 80386, version 1 (GNU/Linux), dynamically linked (uses shared libs), =20
> > 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.
>=20
> Your "appear" is the right word. Licensing issues aside (I try to get =20
> someone to have a look at it), I would import the code as is because =20
> of this and try to fix possible edge cases afterwards. The point is, =20
> we do not really know how much of the structure is used. It may be the =20
> case that the structure is partly compatible (and skype only uses this =20
> part), or compatible by accident (automatic padding by the compiler). =20
> With the right program (printing total size, ofsset of members, and =20
> size of memebers), you can detect both and take appropriate action.
>=20
> Bye,
> Alexander.
>=20
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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