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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <1389661746.1792.254.camel@misato.fc.hp.com>
Date:	Mon, 13 Jan 2014 18:09:06 -0700
From:	Toshi Kani <toshi.kani@...com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Prarit Bhargava <prarit@...hat.com>,
	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 Mon, 2014-01-13 at 16:53 -0800, H. Peter Anvin wrote:
> 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?

Agreed that NUMA info can be bogus in this case, but is probably not
critical.

In majority of the cases, memmap=exactmap is used for kdump and the
firmware info is sane.  So, I think we should keep NUMA enabled since it
could be useful when multiple CPUs are enabled for kdump.

Thanks,
-Toshi


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/