Re: samples don't build on v4.18

On Tue, Aug 14, 2018 at 06:22:21PM -0700, Joel Fernandes wrote:

Forgot to add the patch author, doing so now. thanks

On Tue, Aug 14, 2018 at 6:20 PM, Joel Fernandes [off-list ref] wrote:

quoted

Hi,
When building BPF samples on v4.18, I get the following errors:

$ cd samples/bpf/
$ make

Auto-detecting system features:
...                        libelf: [ OFF ]
...                           bpf: [ OFF ]

No libelf found
Makefile:213: recipe for target 'elfdep' failed
-----------

I bissected it down to commit 5f9380572b4bb24f60cd492b1

Author: Jakub Kicinski [off-list ref]
Date:   Thu May 10 10:24:39 2018 -0700

    samples: bpf: compile and link against full libbpf
---------

Checking out a kernel before this commit makes the samples build. Also I do
have libelf on my system.

Any thoughts on this issue?

There is some weirdness going on with my kernel tree. If I do a fresh clone
of v4.18 and build samples, everything works.

However if I take my existing checkout, do a:
git clean -f -d
make mrproper

Then I try to build the samples, I get the "No libelf found".

Obviously the existing checked out kernel tree is in some weird state that I
am not yet able to fix. But atleast if I blow the whole tree and clone again,
I'm able to build...

Is this related to the intermittent "No libelf found" issues that were
recently discussed?

- Joel