From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Date: Tue, 12 May 2015 14:22:46 +0200
Subject: [Buildroot] [PATCH] libmemcached: don't use -fPIE and -pie with
 FLAT binaries
In-Reply-To: <87wq0egf7w.fsf@dell.be.48ers.dk>
References: <1431377736-2574-1-git-send-email-thomas.petazzoni@free-electrons.com>
 <87d226iwpp.fsf@dell.be.48ers.dk>
 <20150512132632.2cbbc566@free-electrons.com>
 <87wq0egf7w.fsf@dell.be.48ers.dk>
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To: buildroot@busybox.net

Dear Peter Korsgaard,

On Tue, 12 May 2015 14:20:03 +0200, Peter Korsgaard wrote:

> That's also the understanding I get from reading:
> 
> http://retired.beyondlogic.org/uClinux/bflt.htm
> 
> The flat format has its own relocation table that gets applied when
> loading.

Ok.

> I'm not quite sure how this would work with XIP though. The bottom of
> that page mentions that the binary then has to be built in PIC mode.
> 
> But my question was actually why we shouldn't disable PIE/PIC for static
> builds in general, and not just for flat mode?

Yes, -fPIC is not needed for static, but it works (it generates
slightly less efficient code though). But I'm fine with turning this
BR2_BINFMT_FLAT condition to a BR2_STATIC_LIBS condition.

But in practice, they are lots of packages that build code only once to
generate both a shared library and a static library, and they use -fPIC
for both. Guaranteeing that all static libraries have non-PIC code
would be a major effort.

Should I resend an updated patch, or will you commit after doing the
change?

Thanks,

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