linux-kernel - Re: [PATCH 2/2] x86, e820 disable ACPI Memory Hotplug if memory mapping is specified by user [v2]

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Message-ID: <52D48A9D.7000003@zytor.com>
Date:	Mon, 13 Jan 2014 16:53:49 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Toshi Kani <toshi.kani@...com>, Prarit Bhargava <prarit@...hat.com>
CC:	KOSAKI Motohiro <kosaki.motohiro@...il.com>,
	Bodo Eggert <7eggert@....de>,
	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	the arch/x86 maintainers <x86@...nel.org>,
	Len Brown <lenb@...nel.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Linn Crosetto <linn@...com>, Pekka Enberg <penberg@...nel.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tang Chen <tangchen@...fujitsu.com>,
	Wen Congyang <wency@...fujitsu.com>,
	Vivek Goyal <vgoyal@...hat.com>, dyoung@...hat.com,
	linux-acpi@...r.kernel.org,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 2/2] x86, e820 disable ACPI Memory Hotplug if memory mapping
 is specified by user [v2]

On 01/13/2014 04:33 PM, Toshi Kani wrote:
> 
> I do not think it makes sense.  You needed memmap=exactmap as a
> workaround because the kernel did not boot with the firmware's memory
> info.  So, it's broken, and you requested the kernel to ignore the
> firmware info.
> 
> Why do you think memory hotplug needs to be supported under such
> condition, which has to use the broken firmware info?
> 

Even more than memory hotplug: what do we do with NUMA?  Since we have
already told the kernel "the firmware is bogus" it would seem that any
NUMA optimizations would be a bit ... cantankerous at best, no?

	-hpa


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