Date: Sat, 13 Jan 2018 21:31:29 -0800
From: vcaputo@pengaru.com
To: Rob Landley <rob@landley.net>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Commit fc72ae40e303 broke x86-64 build environment.
Message-ID: <20180114053129.f72gfyphp2a6tmb6@shells.gnugeneration.com>
References: <5481b34b-9bf2-4709-8a2f-5cfe4bbcef2c@landley.net>
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On Sat, Jan 13, 2018 at 11:13:13PM -0600, Rob Landley wrote:
> You've made the ORC unwinder part of allnoconfig, which means trying to
> build "make ARCH=x86_64 allnoconfig" requires installing a new package
> (libelf-dev) or else the build breaks.
> 
> What's worse, if I go into menuconfig and switch it back to frame
> pointer, the build STILL breaks:
> 
> $ make -j 8
> Makefile:932: *** "Cannot generate ORC metadata for
> CONFIG_UNWINDER_ORC=y, please install libelf-dev, libelf-devel or
> elfutils-libelf-devel".  Stop.
> $ grep UNWIND .config
> # CONFIG_UNWINDER_ORC is not set
> CONFIG_UNWINDER_FRAME_POINTER=y
> # CONFIG_UNWINDER_GUESS is not set
> 
> As far as I can tell, x86-64 doesn't build anymore without libelf-dev.
> It's a new hard requirement for the build.
> 

FYI this has already been brought up on lkml:
https://patchwork.kernel.org/patch/10137237/

IIRC you can get things working by deleting include/config/auto.conf
when you've switched back to CONFIG_UNWINDER_FRAME_POINTER.

I don't believe anything other than making CONFIG_UNWINDER_ORC the
default was intentional.  The frustration is just a consequence of some
build system bug.

Regards,
Vito Caputo