[Buildroot] [PATCH 1/1] package/zeromq: enable kernel-based feature flags

[Arnout Vandecappelle <arnout@mind.be>]

On 16/03/15 07:43, Lionel Orry wrote:
> Hi Thomas,
> 
> On Sun, Mar 15, 2015 at 11:28 PM, Thomas Petazzoni
> <thomas.petazzoni@free-electrons.com> wrote:
>> Dear Lionel Orry,
>>
>> On Fri,  6 Feb 2015 10:25:52 +0100, Lionel Orry wrote:
>>> The current configuration system does not check for cached variables for
>>> these flags, and thus they are always disabled when cross-compiling.
>>> This patch fixes the configuration system to use cached variables and
>>> enables them at configuration time.
>>>
>>> Signed-off-by: Lionel Orry <lionel.orry@gmail.com>
>>> ---
>>>  ...e.m4-make-kernel-specific-flags-cacheable.patch | 204 +++++++++++++++++++++
>>>  package/zeromq/zeromq.mk                           |  10 +
>>>  2 files changed, 214 insertions(+)
>>>  create mode 100644 package/zeromq/0002-acinclude.m4-make-kernel-specific-flags-cacheable.patch
>>
>> Thanks for this patch, and sorry for the slow response.
>>
>> However, I believe it would be a lot better to change the acinclude.m4
>> tests to not use AC_TRY_RUN, but instead to simply test if TCP_KEEPCNT,
>> TCP_KEEPIDLE, etc. exist at compile time. If they are defined in the
>> kernel headers, then you know the kernel supports them, since running a
>> kernel older than the kernel headers used in the toolchain cannot work.
>>
>> So, replace AC_TRY_RUN with AC_TRY_LINK or something like that. Or
>> maybe there's even a simpler autoconf macro to test if a definition
>> exists or not.
> 
> the fact is, I was asked by Arnout to do it that way, and his opinion
> was that it was needed to run the snippet on the target to be sure of
> the resut. See:
> http://article.gmane.org/gmane.comp.lib.uclibc.buildroot/106055
> 
> Is there something I misunderstood ? Who has the final call about this ?

 It's been a while ago, of course, but I think one problem was that the symbols
are also defined by the toolchain, so they exist even if the kernel doesn't
support them.

 Regards,
 Arnout

-- 
Arnout Vandecappelle                          arnout at mind be
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