[Buildroot] [PATCH 1/1] package/domoticz: fix build with RELRO

[Thomas Petazzoni <thomas.petazzoni@bootlin.com>]

Hello,

I'm adding a few more people in Cc: Matt, Yann, Arnout, Peter.

On Thu, 31 Oct 2019 14:01:33 +0100
Fabrice Fontaine <fontaine.fabrice@gmail.com> wrote:

> > What is the relationship between using precompiled headers and relro
> > build problems ?  
> I took me some time to understand the issue.
> It seems that linker flag such as -Wl,-z,relro should not be used when
> building a precompiled header.
> I discovered this through this domoticz commit message:
> https://github.com/domoticz/domoticz/commit/68698e7a5dce80dea5a9b997d7e171b80bf566ac
> 
> However, this commit does not fix the issue on buildroot as
> -Wl,-z,relro is not passed through CXXFLAGS but through our
> toolchain-wrapper.
> Updating toolchain/toolchain-wrapper.c to add the logic to manage
> precompiled header seems more complicated than adding an option to
> disable this feature from domoticz.

So, I looked into this, found
https://lists.fedoraproject.org/pipermail/devel/2011-July/153664.html
and https://bugzilla.redhat.com/show_bug.cgi?id=718719.

So it really seems like -Wl,-z,relzo should not be passed when
compiling. But our compiler wrapper passes it unconditionally when
RELRO is enabled.

Do we have a way to detect that the wrapper is called to compile or to
link ? I don't think we do.

So is Fabrice's patch an acceptable work-around, or do we want to fix
this more globally ?

Thanks for your feedback,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com