[Buildroot] [PATCH 1/2] package/Makefile.in should grab HOST_DIR headers using -isystem instead of -I.

[Khem Raj <raj.khem@gmail.com>]

On 7/30/16 7:57 AM, David Raeman wrote:
> Yann, All,
> 
> On Fri, Jul 29, 2016 at 5:16 PM, Yann E. MORIN wrote:
>> U-Boot or Qemu? I thought you needed that for your custom Qemu
> 
> The problem was revealed when I added a br2-external package for 
> custom Qemu, but I traced the root issue to be with u-boot and how it
> is impacted by the include directory added by HOST_CPPFLAGS.
> 
> The custom Qemu required me to install libfdt into the host area -
> nothing wrong with doing that.  But having libfdt installed in
> HOST_DIR causes u-boot to fail, because u-boot was finding libfdt.h 
> in HOST_DIR/usr/include prior to searching its own directory for its
> local modified copy of that same filename.

I think thats a problem in u-boot's build system. So its better to
address it there.

> 
>> And thus we should revert that patch. Will you send a patch to do the revert,
>> please?
> 
> Yes I will.  I believe the patch to revert should also back out patch 
> 2/2 that installed libfdt to HOST_DIR as a part of host-dtc.  As 
> mentioned above, if you keep that change and only revert the change to
> HOST_CPPFLAGS, then u-boot to fail unless something else is done.  Do
> you agree I should revert both changes with this new patch, to ensure
> there is no leftover breakage?
> 
>> So, I think the best solution would be for U-Boot^WQemu to rename their
>> header.
> 
> Given the various considerations, I agree this is the lowest-risk
> solution.  Keeping in mind that any other package with a local header
> file in conflict with a HOST_DIR header file can experience this same
> problem.  The root issue is that usage of CPPFLAGS causes packages
> to search HOST_DIR/usr/include before they search their local source
> directories.
> 
> I may be a bit of time before I can submit a new patch to rename the
> header file within u-boot.
> 
> Cheers,
> David
> 
>