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

[Laura Abbott <labbott@redhat.com>]

On 09/09/2016 08:35 AM, Daniel Baluta wrote:
> On Fri, Sep 9, 2016 at 6:24 PM, Laura Abbott <labbott@redhat.com> 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: ‘IIO_UVINDEX’ 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
>> ‘iio_chan_type_name_spec’)
>> iio_event_monitor.c:97:3: error: ‘IIO_MOD_LIGHT_UV’ 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
>> ‘iio_modifier_names’)
>> <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@redhat.com>
>
> 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?

Thanks,
Laura