Re: [tip:x86/pmem] x86/mm: Add support for the non-standard protected e820 type

From: Andy Lutomirski
Date: Thu Apr 02 2015 - 15:51:34 EST


On Thu, Apr 2, 2015 at 12:13 PM, Ingo Molnar <mingo@xxxxxxxxxx> wrote:
>
> * Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>
>> On Thu, Apr 2, 2015 at 5:31 AM, tip-bot for Christoph Hellwig
>> <tipbot@xxxxxxxxx> wrote:
>> > Commit-ID: ec776ef6bbe1734c29cd6bd05219cd93b2731bd4
>> > Gitweb: http://git.kernel.org/tip/ec776ef6bbe1734c29cd6bd05219cd93b2731bd4
>> > Author: Christoph Hellwig <hch@xxxxxx>
>> > AuthorDate: Wed, 1 Apr 2015 09:12:18 +0200
>> > Committer: Ingo Molnar <mingo@xxxxxxxxxx>
>> > CommitDate: Wed, 1 Apr 2015 17:02:43 +0200
>> >
>> > x86/mm: Add support for the non-standard protected e820 type
>> >
>> > 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.
>>
>> This scares me a bit. Do we know that the upcoming ACPI 6.0
>> enumeration mechanism *won't* use e820 type 12? [...]
>
> So I know nothing about it, but I'd be surprised if e820 was touched
> at all, as e820 isn't really well suited to enumerate more complex
> resources, and it appears pmem wants to grow into complex directions?

I hope so, but I have no idea what the ACPI committee's schemes are.

We could require pmem.enable_legacy_e820=Y to load the driver for now
if we're concerned about it.

--Andy

>
> Thanks,
>
> Ingo



--
Andy Lutomirski
AMA Capital Management, LLC
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