Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Fri, 13 Mar 2020 19:06:58 +0100
From:   Borislav Petkov <bp@alien8.de>
To:     Arvind Sankar <nivedita@alum.mit.edu>
Cc:     Hans de Goede <hdegoede@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        "H . Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/2] x86/purgatory: Make sure we fail the build if
 purgatory.ro has missing symbols
Message-ID: <20200313180658.GE8142@zn.tnic>
References: <20200311214601.18141-1-hdegoede@redhat.com>
 <20200311214601.18141-3-hdegoede@redhat.com>
 <20200312001006.GA170175@rani.riverdale.lan>
 <3d58e77d-41e5-7927-fe84-4c058015e469@redhat.com>
 <20200312114225.GB15619@zn.tnic>
 <899f366e-385d-bafa-9051-4e93dc9ba321@redhat.com>
 <20200312125032.GC15619@zn.tnic>
 <20200313044235.GA1159234@rani.riverdale.lan>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20200313044235.GA1159234@rani.riverdale.lan>
User-Agent: Mutt/1.10.1 (2018-07-13)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Fri, Mar 13, 2020 at 12:42:36AM -0400, Arvind Sankar wrote:
>  The real problem is that there exist CFLAGS that should be used for
> all source files in the kernel, and there are CFLAGS (eg tracing,
> stack check etc) that should only be used for the kernel proper. For
> special compilations, such as boot stubs, vdso's, purgatory we should
> have the generic CFLAGS but not the kernel-proper CFLAGS. The issue
> currently is that these special compilations need to filter out all
> the flags added for kernel-proper, and this is a moving target as
> more tracing/sanity flags get added. Neither the solution of simply
> re-initializing CFLAGS (which will miss generic CFLAGS) nor trying to
> filter out CFLAGS (which will miss new kernel-proper CFLAGS) works
> very well. I think ideally splitting these into independent variables,
> i.e. BASE_FLAGS that can be used for everything, and KERNEL_FLAGS
> only to be used for the kernel proper is likely eventually the better
> solution, rather than conflating both into KBUILD_CFLAGS.

Hohumm, this has come up a bunch of times in the past in conjunction
with boot/{,compressed/} Makefiles too. I'd be open towards reworking
this properly but I'm afraid it would cause a lot of churn and breakage
and it is hard to say how ugly it would become before someone actually
tries it. ;-\

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette