[OE-core] libcap: make -e causing trouble

[Christopher Larson]

On Thu, Apr 30, 2015 at 7:28 AM, Mike Crowe <mac at mcrowe.com> wrote:

> oe-core 51540b64f62234c145fc32cfa3fbbaaebbeece08 altered libcap.inc (at the
> time) to append to EXTRA_OEMAKE rather than assign to it. The default value
> for EXTRA_OEMAKE contains "-e". This means that the change caused "-e" to
> be passed to make for the first time.
>
> Unfortunately passing "-e" subtly changes the behaviour of libcap's
> Make.Rules under recursive make when prefix="" (which it is for us since
> we're using meta-micro.) Here's a snippet of Make.rules:
>
> ifdef prefix
> exec_prefix=$(prefix)
> lib_prefix=$(exec_prefix)
> inc_prefix=$(lib_prefix)
> man_prefix=$(prefix)/share
> else
> prefix=/usr
> exec_prefix=
> lib_prefix=$(exec_prefix)
> inc_prefix=$(prefix)
> man_prefix=$(prefix)/share
> endif
>
> Without "-e" the prefix comes from the command line in both the parent and
> submakes. This takes precedence over any attempt to reassign it with a
> simple "=" operation so the headers are correctly installed in (empty
> string)/include.
>
> With "-e" the prefix still comes from the command line in the parent make
> but from the environment in the submake. The attempt to assign it fails in
> the parent make as before, but not in the submake so the headers are
> installed incorrectly in /usr/include.
>
> In all four cases the "ifdef prefix" else clause is executed.
>
> The quick-and-easy fix for this is simply to pass prefix="${prefix}/" but
> it's really just working around the problem.
>
> Alternatively we could go back to assigning EXTRA_OEMAKE rather than
> appending to it.
>
> What would be the preferred course of action?
>

Given our use of make -e (with MAKEFLAGS= to try to prevent it from flowing
into submakes) was always a hack to try to let things "just work", I think
wherever possible we should stop relying on it, and explicitly pass
everything the way that particular make-based buildsystem expects,
personally. Better to be explicit than to rely on implicit "magic".
Further, that behavior encourages recipe maintainers to not even read the
buildsystem of the project they're creating a recipe for, which often leads
to problems down the road..
-- 
Christopher Larson
clarson at kergoth dot com
Founder - BitBake, OpenEmbedded, OpenZaurus
Maintainer - Tslib
Senior Software Engineer, Mentor Graphics
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openembedded.org/pipermail/openembedded-core/attachments/20150430/89a26376/attachment-0002.html>