From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id 09109900194 for ; Thu, 23 Jun 2011 11:38:01 -0400 (EDT) Message-ID: <4E035DD1.1030603@kpanic.de> Date: Thu, 23 Jun 2011 17:37:53 +0200 From: Stefan Assmann MIME-Version: 1.0 Subject: Re: [PATCH v2 0/3] support for broken memory modules (BadRAM) References: <1308741534-6846-1-git-send-email-sassmann@kpanic.de> <20110623133950.GB28333@srcf.ucam.org> <4E0348E0.7050808@kpanic.de> <20110623141222.GA30003@srcf.ucam.org> In-Reply-To: <20110623141222.GA30003@srcf.ucam.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Garrett Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, tony.luck@intel.com, andi@firstfloor.org, mingo@elte.hu, hpa@zytor.com, rick@vanrein.org, rdunlap@xenotime.net On 23.06.2011 16:12, Matthew Garrett wrote: > On Thu, Jun 23, 2011 at 04:08:32PM +0200, Stefan Assmann wrote: >> On 23.06.2011 15:39, Matthew Garrett wrote: >>> Would it be more reasonable to do this in the bootloader? You'd ideally >>> want this to be done as early as possible in order to avoid awkward >>> situations like your ramdisk ending up in the bad RAM area. >> >> Not sure what exactly you are suggesting here. The kernel somehow needs >> to know what memory areas to avoid so we supply this information via >> kernel command line. >> What the bootloader could do is to allow the kernel/initrd to be loaded >> at an alternative address. That's briefly mentioned in the BadRAM >> Documentation as well. Is that what you mean or am I missing something? > > For EFI booting we just hand an e820 map to the kernel. It ought to be > easy enough to add support for that to the 16-bit entry point as well. > Then the bootloader just needs to construct an e820 map of its own. I > think grub2 actually already has some support for this. The advantage of > this approach is that the knowledge of bad memory only has to exist in > one place (ie, the bootloader) - the kernel can remain blisfully > unaware. > According to Rick's reply in this thread a damaged row in a DIMM can easily cause a few thousand entries in the e820 table because it doesn't handle patterns. So the question I'm asking is, is it acceptable to have an e820 table with thousands maybe ten-thousands of entries? I really have no idea of the implications, maybe somebody else can comment on that. Stefan -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org