linux-kernel - Re: [PATCH 1/2] x86: add support for the non-standard protected e820 type

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Message-ID: <CAE9FiQWUKiLLaRSZGCGDZYVuKRgXfCY=7zdx0gp8DM_kH-OBYg@mail.gmail.com>
Date:	Thu, 2 Apr 2015 13:23:22 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	Christoph Hellwig <hch@....de>
Cc:	linux-nvdimm@...1.01.org, linux-fsdevel@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"the arch/x86 maintainers" <x86@...nel.org>,
	Jens Axboe <axboe@...nel.dk>, ross.zwisler@...ux.intel.com,
	Boaz Harrosh <boaz@...xistor.com>
Subject: Re: [PATCH 1/2] x86: add support for the non-standard protected e820 type

On Wed, Apr 1, 2015 at 12:12 AM, Christoph Hellwig <hch@....de> 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.
>
> Based on arlier work from Dave Jiang <dave.jiang@...el.com> and
> Dan Williams <dan.j.williams@...el.com>.
>
...
> @@ -748,7 +758,7 @@ 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, unsigned type)
> +static unsigned long __init e820_end_pfn(unsigned long limit_pfn)
>  {
>         int i;
>         unsigned long last_pfn = 0;
> @@ -759,7 +769,11 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
>                 unsigned long start_pfn;
>                 unsigned long end_pfn;
>
> -               if (ei->type != type)
> +               /*
> +                * Persistent memory is accounted as ram for purposes of
> +                * establishing max_pfn and mem_map.
> +                */
> +               if (ei->type != E820_RAM && ei->type != E820_PRAM)
>                         continue;
>
>                 start_pfn = ei->addr >> PAGE_SHIFT;
> @@ -784,12 +798,12 @@ static unsigned long __init e820_end_pfn(unsigned long limit_pfn, unsigned type)
>  }
>  unsigned long __init e820_end_of_ram_pfn(void)
>  {
> -       return e820_end_pfn(MAX_ARCH_PFN, E820_RAM);
> +       return e820_end_pfn(MAX_ARCH_PFN);
>  }
>
>  unsigned long __init e820_end_of_low_ram_pfn(void)
>  {
> -       return e820_end_pfn(1UL<<(32 - PAGE_SHIFT), E820_RAM);
> +       return e820_end_pfn(1UL<<(32 - PAGE_SHIFT));
>  }

You are using iomap_nocache to access pmem.

Do you still need to account E820_PRAM to get those end_of_ram ?
You should not need that to help to set kernel mapping.

So please drop those not needed changes.

Thanks

Yinghai
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