On Mon, Oct 7, 2019 at 6:10 AM Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> wrote: > > Currently, linux/videodev.h is excluded from the UAPI header test since > it is not self-contained. Building it for user-space would fail. > > > Replacing <sys/time.h> with <linux/time.h> solves it, and allow more > headers to join the UAPI header test. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> > --- > > I am not 100% sure about the compatibility > between <sys/time.h> and <linux/time.h>, hence RFC. > > But, if they were not compatible, > I guess it would have broken already. > > I CCed Arnd Bergmann, who might have a better insight. > > A related comment is here: > https://lkml.org/lkml/2019/6/4/1046 I don't think this can work, there are multiple problems here: * linux/time.h is still incompatible with sys/time.h, so any application tries to include both sys/time.h and linux/videodev2.h now also gets the compile-time error. * The definition of 'struct timespec' in the kernel headers may in fact be different from the one in the libc, and we do want to use the one from the C library here, otherwise different parts of the application may use incompatible struct layouts. Fixing this correctly depends on one of the remaining y2038 patches that we still have to revisit. There are two aspects that we should address: 1. The v4l subsystem needs to be changed to handle both the old and the new 32-bit layout for timespec (and timeval). Both Hans and I have created patches for this in the past, but they were never completed and merged. 2. The definition of 'struct timespec' in the kernel headers needs to be removed after every user of this struct is gone from the kernel. In internal kernel code, the replacement is timespec64 or ktime_t, and in user space interfaces, the correct replacement is one of __kernel_timespec (the 64-bit version), __kernel_old_timespec (the traditional layout) or timespec (from the libc headers). Arnd
