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From: Dan Williams <dan.j.williams@intel.com>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: Christoph Hellwig <hch@lst.de>,
	linux-nvdimm <linux-nvdimm@ml01.01.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	X86 ML <x86@kernel.org>, Jens Axboe <axboe@kernel.dk>
Subject: Re: [Linux-nvdimm] another pmem variant
Date: Mon, 13 Apr 2015 09:02:54 -0700	[thread overview]
Message-ID: <CAPcyv4iezZbqjH_ASPnOw4-j2XuGwBPXJbM8DVz7seX5oMdp8g@mail.gmail.com> (raw)
In-Reply-To: <20150413090133.GA4928@kroah.com>

On Mon, Apr 13, 2015 at 2:01 AM, Greg KH <gregkh@linuxfoundation.org> wrote:
> On Wed, Mar 25, 2015 at 10:00:26AM -0700, Dan Williams wrote:
>> On Wed, Mar 25, 2015 at 9:44 AM, Christoph Hellwig <hch@lst.de> wrote:
>> > On Wed, Mar 25, 2015 at 09:33:52AM -0700, Dan Williams wrote:
>> >> This is mostly ok and does not collide too much with the upcoming ACPI
>> >> mechanism for this stuff.  I do worry that the new
>> >> "memmap=nn[KMG]!ss[KMG]" kernel command line option will only be
>> >> relevant for at most one kernel cycle given the imminent publication
>> >> of the spec that unblocks our release.
>> >
>> > I don't think we can just get rid of it as legacy systems won't be
>> > upgraded to the new discovery mechanism.  Or do you mean you plan to
>> > introduce a better override on the command line?  In that case speak
>> > up now!
>>
>> The kernel command line would simply be the standard/existing memmap=
>> to reserve a memory range.  Then, when the platform device loads, it
>> does a request_firmware() to inject a binary table that further carves
>> memory into ranges to which the pmem driver attaches.  No need for the
>> legacy system BIOS to be upgraded to the "new way".
>
> Um, what parses that "binary table"?  The kernel better not be doing
> that, as that's not what the firmware interface is for.  The firmware
> interface is for "pass through" only directly to hardware.

I had been using it as a generic/device-model-integrated way to do
what amounts to ACPI table injection [1].  But, now that the new
memmap= command line is upstream, most of the benefits of this
approach are moot and no longer outweigh the downsides [2].  Consider
it tabled.


[1]: https://01.org/linux-acpi/documentation/overriding-dsdt
[2]: http://marc.info/?l=linux-netdev&m=135793331325647&w=2

  reply	other threads:[~2015-04-13 16:02 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-25 16:04 another pmem variant Christoph Hellwig
2015-03-25 16:04 ` [PATCH 1/3] pmem: Initial version of persistent memory driver Christoph Hellwig
2015-03-25 20:19   ` Paul Bolle
2015-03-25 20:26     ` Ross Zwisler
2015-03-26  8:04       ` Christoph Hellwig
2015-03-25 20:21   ` Ross Zwisler
2015-03-26  8:06     ` Christoph Hellwig
2015-05-04 16:43       ` Ross Zwisler
2015-05-04 16:43         ` Ross Zwisler
2015-05-07  7:26         ` Christoph Hellwig
2015-05-07  8:35           ` Boaz Harrosh
2015-03-25 16:04 ` [PATCH 2/3] x86: add a is_e820_ram() helper Christoph Hellwig
2015-03-26  2:15   ` [Linux-nvdimm] " Dan Williams
2015-03-26  8:01     ` Christoph Hellwig
2015-03-26 13:57       ` Dan Williams
2015-03-26 14:32         ` Christoph Hellwig
2015-03-25 16:04 ` [PATCH 3/3] x86: add support for the non-standard protected e820 type Christoph Hellwig
2015-03-25 19:47   ` Elliott, Robert (Server Storage)
2015-03-26  8:02     ` Christoph Hellwig
2015-03-25 20:23   ` Ross Zwisler
2015-03-25 20:29     ` [Linux-nvdimm] " Dan Williams
2015-03-25 20:25   ` Ross Zwisler
2015-03-26  8:03     ` Christoph Hellwig
2015-03-25 20:35   ` [Linux-nvdimm] " Dan Williams
2015-03-25 16:33 ` [Linux-nvdimm] another pmem variant Dan Williams
2015-03-25 16:44   ` Christoph Hellwig
2015-03-25 17:00     ` Dan Williams
2015-03-25 17:04       ` Christoph Hellwig
2015-03-25 17:18         ` Dan Williams
2015-04-13  9:01       ` Greg KH
2015-04-13 16:02         ` Dan Williams [this message]
2015-03-25 18:09 ` Brooks, Adam J
2015-03-25 18:09   ` Brooks, Adam J
2015-03-25 18:46   ` Christoph Hellwig
2015-03-25 21:02 ` Ross Zwisler

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