linux-kernel - Re: [PATCH] ARM: pxa: Move iotable mapping inside vmalloc region

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Message-ID: <alpine.LFD.2.10.1311241824380.9667@knanqh.ubzr>
Date:	Sun, 24 Nov 2013 18:26:45 -0500 (EST)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>
cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	eric.y.miao@...il.com, haojian.zhuang@...il.com
Subject: Re: [PATCH] ARM: pxa: Move iotable mapping inside vmalloc region

On Sun, 24 Nov 2013, Ezequiel Garcia wrote:

> In order to remove the following ugly message:
> 
>   BUG: mapping for 0x00000000 at 0xff000000 out of vmalloc space
> 
> the iotable mappings should be re-located inside the vmalloc
> region. Such move was introduced at commit:
> 
> commit 0536bdf33faff4d940ac094c77998cfac368cfff
> Author: Nicolas Pitre <nicolas.pitre@...aro.org>
> Date:   Thu Aug 25 00:35:59 2011 -0400
> 
>     ARM: move iotable mappings within the vmalloc region
> 
> While at it, let's add some nicer defines to make the code
> more readable.
> 
> Cc: Nicolas Pitre <nicolas.pitre@...aro.org>
> Signed-off-by: Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>
> ---
>  arch/arm/mach-pxa/generic.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mach-pxa/generic.c b/arch/arm/mach-pxa/generic.c
> index 4225417..7c01095 100644
> --- a/arch/arm/mach-pxa/generic.c
> +++ b/arch/arm/mach-pxa/generic.c
> @@ -24,6 +24,7 @@
>  #include <mach/hardware.h>
>  #include <asm/mach/map.h>
>  #include <asm/mach-types.h>
> +#include <asm/pgtable.h>
>  
>  #include <mach/reset.h>
>  #include <mach/smemc.h>
> @@ -77,6 +78,11 @@ EXPORT_SYMBOL(get_clk_frequency_khz);
>   * Note: virtual 0xfffe0000-0xffffffff is reserved for the vector table
>   *       and cache flush area.
>   */
> +
> +#define UNCACHED_PHY	0x00000000
> +#define UNCACHED_SIZE	SZ_1M
> +#define UNCACHED_VIRT	(VMALLOC_END - UNCACHED_SIZE)
> +
>  static struct map_desc common_io_desc[] __initdata = {
>    	{	/* Devs */
>  		.virtual	=  0xf2000000,
> @@ -84,9 +90,9 @@ static struct map_desc common_io_desc[] __initdata = {
>  		.length		= 0x02000000,
>  		.type		= MT_DEVICE
>  	}, {	/* UNCACHED_PHYS_0 */
> -		.virtual	= 0xff000000,
> -		.pfn		= __phys_to_pfn(0x00000000),
> -		.length		= 0x00100000,
> +		.virtual	= UNCACHED_VIRT,
> +		.pfn		= __phys_to_pfn(UNCACHED_PHY),
> +		.length		= UNCACHED_SIZE,
>  		.type		= MT_DEVICE
>  	}
>  };

You might wish to change the virtual address for this mapping, but 
nowhere in your patch you are changing users of that virtual mapping.


Nicolas
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