lkml.org 
[lkml]   [2015]   [Apr]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [Linux-nvdimm] another pmem variant
From
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


\
 
 \ /
  Last update: 2015-04-13 18:41    [W:0.099 / U:1.244 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site