linux-kernel - Re: [RFC] x86: mtrr: Constrain WB MTRR to max phys mem prior to cleanup

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]

Date:	Mon, 10 Sep 2012 11:54:56 +0800
From:	"zhenzhong.duan" <zhenzhong.duan@...cle.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Peter Hurley <peter@...leysoftware.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC] x86: mtrr: Constrain WB MTRR to max phys mem prior to cleanup



于 2012-09-08 02:40, H. Peter Anvin 写道:
> On 09/07/2012 10:44 AM, Peter Hurley wrote:
> \>
>> diff --git a/arch/x86/kernel/cpu/mtrr/cleanup.c 
>> b/arch/x86/kernel/cpu/mtrr/cleanup.c
>
> I really don't like it as it introduces yet another user of max_pfn, 
> which should be going away.  Furthermore, the better question is what 
> remaining needs there are for MTRR cleanup; historically the reason 
> was that it prevented the display from being mapped WC via MTRR due to 
> the MTRR conflict resolution rules favoring UC.
For a large memory system, mtrr_cleanup offten fail in most case. Even 
if it succeed, it often occupy all of MTRR entrys.
How was display mapped as WC in above case?
Why did bios give a lot of space then real mem, for hotplug?
>
> However, the right way to fix that is to use the PAT interfaces, which 
> doesn't have this drawback -- then MTRR cleanup becomes entirely 
> superfluous and the problem goes away.
Do you mean disable MTRR totally here?
Regards
zduan
--
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/