linux-kernel - Re: [PATCH] x86, acpi: Remove out-of-date comment of __acpi_map

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Date:	Tue, 23 Jul 2013 11:22:14 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Zhang Yanfei <zhangyanfei.yes@...il.com>
Cc:	len.brown@...el.com, pavel@....cz, rjw@...k.pl,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86, acpi: Remove out-of-date comment of __acpi_map_table


* Zhang Yanfei <zhangyanfei.yes@...il.com> wrote:

> From: Zhang Yanfei <zhangyanfei@...fujitsu.com>
> 
> The implementation of function __acpi_map_table() has been changed
> long time ago, and now it directly invokes early_ioremap() to setup
> the temporarily acpi table mappings. So remove its out-of-date
> comment.
> 
> Signed-off-by: Zhang Yanfei <zhangyanfei@...fujitsu.com>
> ---
>  arch/x86/kernel/acpi/boot.c |   13 +------------
>  1 files changed, 1 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index d81a972..bac8b5b 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -140,18 +140,6 @@ static u32 irq_to_gsi(int irq)
>  	return gsi;
>  }
>  
> -/*
> - * Temporarily use the virtual area starting from FIX_IO_APIC_BASE_END,
> - * to map the target physical address. The problem is that set_fixmap()
> - * provides a single page, and it is possible that the page is not
> - * sufficient.
> - * By using this area, we can map up to MAX_IO_APICS pages temporarily,
> - * i.e. until the next __va_range() call.
> - *
> - * Important Safety Note:  The fixed I/O APIC page numbers are *subtracted*
> - * from the fixed base.  That's why we start at FIX_IO_APIC_BASE_END and
> - * count idx down while incrementing the phys address.
> - */
>  char *__init __acpi_map_table(unsigned long phys, unsigned long size)

Good catch. Removing documentation makes me sad, so how about replacing it 
with a simple comment:

	/*
	 * This is just a simple wrapper around early_ioremap(),
	 * with sanity checks for phys == 0 and size == 0:
	 */

?

Thanks,

	Ingo
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