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

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Date:   Tue, 13 Feb 2018 21:16:55 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Kees Cook <keescook@...omium.org>
Cc:     Michal Hocko <mhocko@...nel.org>, Will Drewry <wad@...omium.org>,
        linux-s390 <linux-s390@...r.kernel.org>,
        PowerPC <linuxppc-dev@...ts.ozlabs.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: samples/seccomp/ broken when cross compiling s390, ppc allyesconfig

Kees Cook <keescook@...omium.org> writes:

> On Mon, Feb 12, 2018 at 7:25 PM, Michael Ellerman <mpe@...erman.id.au> wrote:
>> Michal Hocko <mhocko@...nel.org> 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?

cheers