linux-kernel - Re: [PATCH 3/3] x86: add support for the non-standard protected e820 type

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Date:	Wed, 25 Mar 2015 14:23:38 -0600
From:	Ross Zwisler <ross.zwisler@...ux.intel.com>
To:	Christoph Hellwig <hch@....de>
Cc:	linux-nvdimm@...1.01.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, x86@...nel.org, boaz@...xistor.com,
	axboe@...nel.dk
Subject: Re: [PATCH 3/3] x86: add support for the non-standard protected
 e820 type

On Wed, 2015-03-25 at 17:04 +0100, Christoph Hellwig wrote:
> Various recent bioses support NVDIMMs or ADR using a non-standard
> e820 memory type, and Intel supplied reference Linux code using this
> type to various vendors.
> 
> Wire this e820 table type up to export platform devices for the pmem
> driver so that we can use it in Linux, and also provide a memmap=
> argument to manually tag memory as protected, which can be used
> if the bios doesn't use the standard nonstandard interface, or
> we just want to test the pmem driver with regular memory.
> 
> Based on an earlier patch from Dave Jiang <dave.jiang@...el.com>
> Signed-off-by: Christoph Hellwig <hch@....de>

<snip>

> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index b7d31ca..93a27e4 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1430,6 +1430,19 @@ config ILLEGAL_POINTER_VALUE
>  
>  source "mm/Kconfig"
>  
> +config X86_PMEM_LEGACY
> +	bool "Support non-stanard NVDIMMs and ADR protected memory"
> +	help
> +	  Treat memory marked using the non-stard e820 type of 12 as used
> +	  by the Intel Sandy Bridge-EP reference BIOS as protected memory.
> +	  The kernel will the offer these regions to the pmem driver so
> +	  they can be used for persistent storage.
> +
> +	  If you say N the kernel will treat the ADR region like an e820
> +	  reserved region.
> +
> +	  Say Y if unsure

Would it make sense to have this default to "y", or is that too strong?


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