Re: samples/seccomp/ broken when cross compiling s390, ppc allyesconfig

[Michal Hocko]

On Tue 13-02-18 13:27:30, Kees Cook wrote:
> On Tue, Feb 13, 2018 at 2:32 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> > On Tue 13-02-18 21:16:55, Michael Ellerman wrote:
> >> Kees Cook <keescook@xxxxxxxxxxxx> writes:
> >>
> >> > On Mon, Feb 12, 2018 at 7:25 PM, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
> >> >> Michal Hocko <mhocko@xxxxxxxxxx> writes:
> >> >>> Hi,
> >> >>> my build test machinery chokes on samples/seccomp when cross compiling
> >> >>> s390 and ppc64 allyesconfig. This has been the case for quite some
> >> >>> time already but I never found time to look at the problem and report
> >> >>> it. It seems this is not new issue and similar thing happend for
> >> >>> MIPS e9107f88c985 ("samples/seccomp/Makefile: do not build tests if
> >> >>> cross-compiling for MIPS").
> >> >>>
> >> >>> The build logs are attached.
> >> >>>
> >> >>> What is the best way around this? Should we simply skip compilation on
> >> >>> cross compile or is actually anybody relying on that? Or should I simply
> >> >>> disable it for s390 and ppc?
> >> >>
> >> >> The whole thing seems very confused. It's not building for the target,
> >> >> it's building for the host, ie. the Makefile sets hostprogs-m and
> >> >> HOSTCFLAGS etc.
> >> >>
> >> >> So it can't possibly work with cross compiling as it's currently
> >> >> written.
> >> >>
> >> >> Either the Makefile needs some serious work to properly support cross
> >> >> compiling or it should just be disabled when cross compiling.
> >> >
> >> > Hrm, yeah, the goal was to entirely disable cross compiling, but I
> >> > guess we didn't hit it with a hard enough hammer. :)
> >>
> >> Do you know why it is written that way? Why doesn't it just try to cross
> >> compile like normal code?
> >
> > No idea, sorry. All I know about this code is that it breaks my build
> > testing.
> 
> IIRC, one of the problems is with build ordering problems: the kernel
> headers used by the samples aren't available when cross compiling.
> 
> I'm happy to kill it entirely with Michal's patch, though. Feel free
> to carry in your tree!
> 
> Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>

OK, so let's try to nuke it. How should I route this patch?