lkml.org 
[lkml]   [2014]   [Jan]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH 2/2] x86, e820 disable ACPI Memory Hotplug if memory mapping is specified by user [v2]
On Sun, Jan 12, 2014 at 6:46 PM, Prarit Bhargava <prarit@redhat.com> wrote:
>
>
> On 01/11/2014 11:35 AM, 7eggert@gmx.de wrote:
>>
>>
>> On Fri, 10 Jan 2014, Prarit Bhargava wrote:
>>
>>> kdump uses memmap=exactmap and mem=X values to configure the memory
>>> mapping for the kdump kernel. If memory is hotadded during the boot of
>>> the kdump kernel it is possible that the page tables for the new memory
>>> cause the kdump kernel to run out of memory.
>>>
>>> Since the user has specified a specific mapping ACPI Memory Hotplug should be
>>> disabled in this case.
>>
>> I'll ask just in case: Is it possible to want memory hotplug in spite of
>> using memmap=exactmap or mem=X?
>
> Good question -- I can't think of a case. When a user specifies "memmap" or
> "mem" IMO they are asking for a very specific memory configuration. Having
> extra memory added above what the user has specified seems to defeat the purpose
> of "memmap" and "mem".

May be yes, may be no.

They are often used for a wrokaround to avoid broken firmware issue.
If we have no way
to explicitly enable hotplug. We will lose a workaround.

Perhaps, there is no matter. Today, memory hotplug is only used on
high-end machine
and their firmware is carefully developped and don't have a serious
issue almostly. Though.


\
 
 \ /
  Last update: 2014-01-13 22:01    [W:0.059 / U:3.296 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site