linux-kernel - Re: [PATCH 12/12] x86/ACPI/sleep: Move acpi_wakeup

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Date:   Wed, 20 Nov 2019 12:00:48 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, 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 <ardb@...nel.org>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Nadav Amit <namit@...are.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 12/12] x86/ACPI/sleep: Move acpi_wakeup_address() definition into sleep.c

On Tuesday, November 19, 2019 1:21:21 AM CET Sean Christopherson wrote:
> Move the definition of acpi_wakeup_address() into sleep.c to break
> linux/acpi.h's dependency (by way of asm/acpi.h) on asm/realmode.h.
> Everyone and their mother includes linux/acpi.h, i.e. modifying
> realmode.h results in a full kernel rebuild, which makes the already
> inscrutable real mode boot code even more difficult to understand and is
> positively rage inducing when trying to make changes to x86's boot flow.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

> ---
>  arch/x86/include/asm/acpi.h  |  6 +-----
>  arch/x86/kernel/acpi/sleep.c | 11 +++++++++++
>  2 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/include/asm/acpi.h b/arch/x86/include/asm/acpi.h
> index 57788ec6fa82..0cae3f773d44 100644
> --- a/arch/x86/include/asm/acpi.h
> +++ b/arch/x86/include/asm/acpi.h
> @@ -13,7 +13,6 @@
>  #include <asm/processor.h>
>  #include <asm/mmu.h>
>  #include <asm/mpspec.h>
> -#include <asm/realmode.h>
>  #include <asm/x86_init.h>
>  
>  #ifdef CONFIG_ACPI_APEI
> @@ -62,10 +61,7 @@ static inline void acpi_disable_pci(void)
>  extern int (*acpi_suspend_lowlevel)(void);
>  
>  /* Physical address to resume after wakeup */
> -static inline unsigned long acpi_wakeup_address(void)
> -{
> -	return ((unsigned long)(real_mode_header->wakeup_start));
> -}
> +unsigned long acpi_wakeup_address(void);
>  
>  /*
>   * Check if the CPU can handle C2 and deeper
> diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> index ca13851f0570..44d3fb1a1de3 100644
> --- a/arch/x86/kernel/acpi/sleep.c
> +++ b/arch/x86/kernel/acpi/sleep.c
> @@ -26,6 +26,17 @@ unsigned long acpi_realmode_flags;
>  static char temp_stack[4096];
>  #endif
>  
> +/**
> + * acpi_wakeup_address - provide physical address for S3 wakeup
> + *
> + * Returns the physical address where the kernel should be resumed after the
> + * system awakes from S3, e.g. for programming into the firmware waking vector.
> + */
> +unsigned long acpi_wakeup_address(void)
> +{
> +	return ((unsigned long)(real_mode_header->wakeup_start));
> +}
> +
>  /**
>   * x86_acpi_enter_sleep_state - enter sleep state
>   * @state: Sleep state to enter.
>