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

[Thomas Petazzoni <thomas.petazzoni@free-electrons.com>]

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.

Can you try this instead?

Also, did you submit your patch upstream?

Thanks a lot,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com