Messages in this thread | | | Subject | Re: [v4l-dvb-maintainer] Re: [PATCH] V4L: struct video_device corruption | From | Mauro Carvalho Chehab <> | Date | Wed, 19 Jul 2006 08:54:52 -0300 |
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Em Seg, 2006-07-17 às 17:25 -0700, Trent Piepho escreveu: > On Sat, 15 Jul 2006, Mauro Carvalho Chehab wrote: > > Em Sb, 2006-07-15 s 23:08 +0000, Robert Fitzsimons escreveu: > > > The layout of struct video_device would change depending on whether > > > videodev.h (V4L1) was include or not before v4l2-dev.h, which caused > > > the structure to get corrupted. > > Hmm... good point! However, I the proper solution would be to trust on > > CONFIG_VIDEO_V4L1_COMPAT or CONFIG_VIDEO_V4L1 instead. it makes no sense > > to keep a pointer to an unsupported callback, when V4L1 is not selected. > > It's not so clear that the problem is with v4l2-dev.h, because if you look > that file: > > #ifdef CONFIG_VIDEO_V4L1 > #include <linux/videodev.h> > #else > #include <linux/videodev2.h> > #endif That's true. I think the OOPS is related to this -git patch: http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=6ab3d5624e172c553004ecc862bfeac16d9d68b7
It removed config.h from bttv-cards (and other places), but we need CONFIG_* symbols before including v4l2-dev.h. Maybe the right solution would be to include autoconf.h or config.h at the top of v4l2-dev.h.
> > linux/videodev.h is where HAVE_V4L1 is defined (always). So, if > CONFIG_VIDEO_V4L1 is set, then HAVE_V4L1 must also bet set. > > I think that the real problem is that many drivers include the V4L1 API > file videodev.h when V4L1 is NOT on. Should drivers be providing V4L1 API > functions, or need anything from videodev.h, if V4L1 is not on? > > It seems like they either need to depend on VIDEO_V4L1 or only include the > V4L1 API header file when V4L1 is turned on. Which also means they would > need to #ifdef out any V4L1 code when V4L1 is turned off. The bttv driver > for example does not do this. It includes a bunch of V4L1 functions even > when V4L1 (and V4L1_COMPAT) are turned off. > > BTW, I think the CONFIG_VIDEO_V4L1 check in v4l2-dev.h should instead check > for CONFIG_VIDEO_V4L1_COMPAT. For example, cx88-video.c includes > videodev.h when CONFIG_VIDEO_V4L1_COMPAT is turned on. Yes, you are right. Checking for COMPAT covers both cases.
Cheers, Mauro.
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