Message-ID: <54E2FEF2.8060701@plexistor.com>
Date: Tue, 17 Feb 2015 10:42:26 +0200
From: Boaz Harrosh <boaz@plexistor.com>
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To: Matthew Wilcox <willy@linux.intel.com>
CC: Ingo Molnar <mingo@redhat.com>,
        Ross Zwisler <ross.zwisler@linux.intel.com>, x86@kernel.org,
        linux-kernel <linux-kernel@vger.kernel.org>,
        "Roger C. Pao" <rcpao.enmotus@gmail.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-nvdimm <linux-nvdimm@ml01.01.org>,
        "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [Linux-nvdimm] [PATCH 0/2] e820: Fix handling of NvDIMM chips
References: <54E1CF5B.9020905@plexistor.com> <20150216220302.GF3364@wil.cx>
In-Reply-To: <20150216220302.GF3364@wil.cx>
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On 02/17/2015 12:03 AM, Matthew Wilcox wrote:
> On Mon, Feb 16, 2015 at 01:07:07PM +0200, Boaz Harrosh wrote:
>> In any way this is a problem for the new type-12 NvDIMM memory chips that
>> are circulating around. (It is estimated that there are already 100ds of
>> thousands NvDIMM chips in active use)
> 
> Hang on.  NV-DIMM chips don't know anyhing about E820 tables.  They don't
> have anything in them that says "I am type 12!".  How they are reported
> is up to the BIOS.  Just because your BIOS vendor has chosen to report
> tham as type 12 doesn't mean that any other BIOS vedor is going to have
> done the same thing.
> 
> Fortunately, the BIOS people have all got together and decided what
> they're going to do, and it's not type 12.  Unfortunately, I think
> I'm bound by various agreements to not say what they are going to do
> until they do.  But putting this temporary workaround in the kernel to
> accomodate one BIOS vendor's unreleased experimental code seems like
> entirely the wrong idea.
> 

I had a feeling I'm entering an holy war ;-).

I hope you are OK with my first patch. That an unknown type need not
be reported busy, and behave same as "reserved"?

Then if we agree about PATCH-1, which is the actual fix.
Then the 2nd patch (hence the RFC btw) is nothing more than
a name.

I have an old BIOS that knows nothing of NvDIMM, actually a few
of them they all report 12.
The fact of the matter is that all the people I've talked with,
reported that different vendor chips, all came up type-12.
Perhaps type-12 just means "Unknown to current BIOS"

What is the name you suggest "type-12" "unknown-12".
Do you understand why they all come out 12 ?

Thanks
Boaz

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