Commit fc72ae40e303 broke x86-64 build environment.

Commit fc72ae40e303 broke x86-64 build environment.

[Rob Landley]

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.

Why?

Rob

Re: Commit fc72ae40e303 broke x86-64 build environment.

[vcaputo]

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