Re: [PATCH] iio: Use type header from kernel tree

[Laura Abbott]

On 09/10/2016 08:01 AM, Jonathan Cameron wrote:
> On 09/09/16 16:47, Laura Abbott wrote:
> > On 09/09/2016 08:35 AM, Daniel Baluta wrote:
> > > On Fri, Sep 9, 2016 at 6:24 PM, Laura Abbott <labbott@xxxxxxxxxx> wrote:
> > > > The iio tools have been updated as new event types have been added to
> > > > the kernel. The tools currently use the standard system headers which
> > > > means that the system may not have the newest defintitions. This leads
> > > > to build failures when building newer tools on older hosts:
> > > >
> > > > gcc -Wall -g -D_GNU_SOURCE   -c -o iio_event_monitor.o
> > > > iio_event_monitor.c
> > > > iio_event_monitor.c:59:3: error: âIIO_UVINDEXâ undeclared here (not in a
> > > > function)
> > > >   [IIO_UVINDEX] = "uvindex",
> > > >    ^~~~~~~~~~~
> > > > iio_event_monitor.c:59:3: error: array index in initializer not of
> > > > integer type
> > > > iio_event_monitor.c:59:3: note: (near initialization for
> > > > âiio_chan_type_name_specâ)
> > > > iio_event_monitor.c:97:3: error: âIIO_MOD_LIGHT_UVâ undeclared here (not
> > > > in a function)
> > > >   [IIO_MOD_LIGHT_UV] = "uv",
> > > >    ^~~~~~~~~~~~~~~~
> > > > iio_event_monitor.c:97:3: error: array index in initializer not of
> > > > integer type
> > > > iio_event_monitor.c:97:3: note: (near initialization for
> > > > âiio_modifier_namesâ)
> > > > <builtin>: recipe for target 'iio_event_monitor.o' failed
> > > >
> > > > Switch to using the header from the kernel tree to ensure the newest
> > > > defintions are always picked up.
> > > >
> > > > Signed-off-by: Laura Abbott <labbott@xxxxxxxxxx>
> > >
> > > Hi Laura,
> > >
> > > Thanks for your patch. The solution here would be to install the
> > > headers for your
> > > new kernel in order to use the updated types.
> > >
> > > That is you should run make headers_install.
> > >
> > > $ make help | grep headers
> > >   headers_install - Install sanitised kernel headers to INSTALL_HDR_PATH
> > >
> > > You can use INSTALL_HDR_PATH to put the headers in a custom directory
> > > and tell gcc to also include this directory when searching for include headers.
> >
> > That's a pretty ugly solution. We want to build this as part of Fedora
> > and installing another local copy of the headers in the build environment
> > complicates an already complicated build process. This is more work
> > for users building on their own as well. Several other tools in the tools
> > directory already use the headers from the kernel tree, is there a reason
> > iio doesn't want to as well?
> This got raised as a suggestion for discussion at the kernel summit this
> year.  Clearly a somewhat contentious topic ;)
>
> https://lists.linuxfoundation.org/pipermail/ksummit-discuss/2016-September/003829.html
>
> I'd prefer to see some resolution on that discussion before making any changes.
> Looks like there are some moves afoot to standardise a lot of this stuff in
> tools.
>
> I've cc'd Ben who raised this particular issue in the first place.

Yes, some consistency would be useful across all tools. I really just want
'make' to work on all the tools directories without having to worry about
what kernel/headers are installed. I'll be around ksummit/plumbers so I'm
happy to talk more there.

Thanks,
Laura

> Jonathan
> > Thanks,
> > Laura