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Date: Thu, 26 Mar 2015 09:02:20 -0700
Message-ID: <CAPcyv4h3QWnhTvxrpcWy6QGLcfQH97uOhPHYuQgVjC9tViqO1w@mail.gmail.com>
Subject: Re: [Linux-nvdimm] [PATCH 2/3] x86: add a is_e820_ram() helper
From: Dan Williams <dan.j.williams@intel.com>
To: Boaz Harrosh <boaz@plexistor.com>
Cc: Christoph Hellwig <hch@lst.de>, Ingo Molnar <mingo@kernel.org>,
        Jens Axboe <axboe@kernel.dk>, linux-nvdimm <linux-nvdimm@ml01.01.org>,
        X86 ML <x86@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>
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On Thu, Mar 26, 2015 at 8:49 AM, Boaz Harrosh <boaz@plexistor.com> wrote:
> On 03/26/2015 11:34 AM, Christoph Hellwig wrote:
>> +/*
>> + * This is a non-standardized way to represent ADR or NVDIMM regions that
>> + * persist over a reboot.  The kernel will ignore their special capabilities
>> + * unless the CONFIG_X86_PMEM_LEGACY option is set.
>> + *
>> + * Note that older platforms also used 6 for the same type of memory,
>> + * but newer versions switched to 12 as 6 was assigned differently.  Some
>> + * time they will learn..
>> + */
>> +#define E820_PRAM    12
>
> Why the PRAM Name. For one 2/3 of this patch say PMEM the Kconfig
> to enable is _PMEM_, the driver stack that gets loaded is pmem,
> so PRAM is unexpected.
>
> Also I do believe PRAM is not the correct name. Yes NvDIMMs are RAM,
> but there are other not RAM technologies that can be supported exactly
> the same way.
> MEM is a more general name meaning "on the memory bus". I think.
>
> I would love the consistency.

One of nice side of effects of having a "PRAM" name is that we can
later add a UEFI "PMEM" type where the distinction is thsy "PRAM" is
included in the system memory map by default and "PMEM" is analogous
to "IOMEM".  Just a thought...