linux-kernel - Re: [PATCH 27/42] x86: restore end_of_ram to E820

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Date:	Wed, 8 Jul 2015 18:44:09 +0100
From:	Matt Fleming <matt@...eblueprint.co.uk>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Kees Cook <keescook@...omium.org>,
	"H. Peter Anvin" <hpa@...or.com>, Baoquan He <bhe@...hat.com>,
	linux-kernel@...r.kernel.org, Christoph Hellwig <hch@....de>,
	Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH 27/42] x86: restore end_of_ram to E820_RAM

On Tue, 07 Jul, at 01:20:13PM, Yinghai Lu wrote:
> We don't need to create mapping for E820_PRAM.
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---
>  arch/x86/kernel/e820.c | 12 ++++--------
>  1 file changed, 4 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
> index a102564..46ec08d 100644
> --- a/arch/x86/kernel/e820.c
> +++ b/arch/x86/kernel/e820.c
> @@ -753,7 +753,7 @@ u64 __init early_reserve_e820(u64 size, u64 align)
>  /*
>   * Find the highest page frame number we have available
>   */
> -static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
> +static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
>  {
>  	int i;
>  	unsigned long last_pfn = 0;
> @@ -764,11 +764,7 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
>  		unsigned long start_pfn;
>  		unsigned long end_pfn;
>  
> -		/*
> -		 * Persistent memory is accounted as ram for purposes of
> -		 * establishing max_pfn and mem_map.
> -		 */
> -		if (ei->type != E820_RAM && ei->type != E820_PRAM)
> +		if (ei->type != type)
>  			continue;
>  
>  		start_pfn = ei->addr >> PAGE_SHIFT;
> @@ -793,12 +789,12 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
>  }
>  unsigned long __init e820_end_of_ram_pfn(void)
>  {
> -	return e820_end_pfn(MAX_ARCH_PFN);
> +	return e820_end_pfn(MAX_ARCH_PFN, E820_RAM);
>  }
>  
>  unsigned long __init e820_end_of_low_ram_pfn(void)
>  {
> -	return e820_end_pfn(1UL << (32-PAGE_SHIFT));
> +	return e820_end_pfn(1UL<<(32 - PAGE_SHIFT), E820_RAM);
>  }
>  
>  static void early_panic(char *msg)

Could you explain why you no longer want to allow pesistent memory to be
used in figuring out max_pfn? This partially reverts commit ec776ef6bbe1
("x86/mm: Add support for the non-standard protected e820 type").

-- 
Matt Fleming, Intel Open Source Technology Center
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