linux-kernel - Re: [PATCH v2 00/12] treewide: break dependencies on x86's RM header

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Message-ID: <20191127144703.GA18530@linux.intel.com>
Date:   Wed, 27 Nov 2019 06:47:03 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Tony Luck <tony.luck@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Nadav Amit <nadav.amit@...il.com>,
        "VMware, Inc." <pv-drivers@...are.com>,
        Arnd Bergmann <arnd@...db.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Hans de Goede <hdegoede@...hat.com>,
        Cezary Rojewski <cezary.rojewski@...el.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>,
        Liam Girdwood <liam.r.girdwood@...ux.intel.com>,
        Jie Yang <yang.jie@...ux.intel.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>, linux-ia64@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-acpi@...r.kernel.org, alsa-devel@...a-project.org
Subject: Re: [PATCH v2 00/12] treewide: break dependencies on x86's RM header

On Wed, Nov 27, 2019 at 08:20:57AM +0100, Ingo Molnar wrote:
> 
> * Sean Christopherson <sean.j.christopherson@...el.com> wrote:
> 
> > x86's asm/realmode.h, which defines low level structures, variables and
> > helpers used to bring up APs during SMP boot, ends up getting included in
> > practically every nook and cranny of the kernel because the address used
> > by ACPI for resuming from S3 also happens to be stored in the real mode
> > header, and ACPI bleeds the dependency into its widely included headers.
> > 
> > As a result, modifying realmode.h for even the most trivial change to the
> > boot code triggers a full kernel rebuild, which is frustrating to say the
> > least as it some of the most difficult code to get exactly right *and* is
> > also some of the most functionally isolated code in the kernel.
> > 
> > To break the kernel's widespread dependency on realmode.h, add a wrapper
> > in the aforementioned ACPI S3 code to access the real mode header instead
> > of derefencing the header directly in asm/acpi.h and thereby exposing it
> > to the world via linux/acpi.h.
> > 
> > v2:
> >   - Rebased on tip/x86/cleanups, commit b74374fef924 ("x86/setup: Enhance
> >     the comments").
> >   - Use acpi_get_wakeup_address() as new function name. [Boris and Pavel]
> >   - Capture acpi_get_wakeup_address() in a local address. [Pavel]
> >   - Collect acks.  I didn't add Rafael's acks on patches 11 and 12 due to
> >     the above changes.
> >   - Explicitly call out the removal of <asm/realmode.h> from <asm/acpi.h>
> >     in patch 12. [Ingo]
> >   - Remove superfluous Fixes: tags. [Ard]
> 
> You didn't include every patch from v1 though, such us my fix to Quark:
> 
>   [PATCH] x86/platform/intel/quark: Explicitly include linux/io.h for virt_to_phys()
> 
> I've applied that one too and your updated patches, and it's now all 
> pushed out into tip:WIP.core/headers.

Sorry, it wasn't clear to me whether or not to include that one.  Next
time I'll ask.