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

Arnout Vandecappelle arnout at mind.be
Wed Mar 18 22:27:55 UTC 2015

On 16/03/15 07:43, Lionel Orry wrote:
> Hi Thomas,
> On Sun, Mar 15, 2015 at 11:28 PM, Thomas Petazzoni
> <thomas.petazzoni at 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 at 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.


Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
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