From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id 4EFDC6B0011 for ; Thu, 28 Apr 2011 02:34:19 -0400 (EDT) Message-ID: <4DB90A66.3020805@kpanic.de> Date: Thu, 28 Apr 2011 08:34:14 +0200 From: Stefan Assmann MIME-Version: 1.0 Subject: Re: [RFC PATCH 2/3] support for broken memory modules (BadRAM) References: <1303921007-1769-1-git-send-email-sassmann@kpanic.de> <1303921007-1769-3-git-send-email-sassmann@kpanic.de> <20110427211258.GQ16484@one.firstfloor.org> In-Reply-To: <20110427211258.GQ16484@one.firstfloor.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andi Kleen Cc: linux-mm@kvack.org, tony.luck@intel.com, mingo@elte.hu, hpa@zytor.com, rick@vanrein.org, akpm@linux-foundation.org, lwoodman@redhat.com, riel@redhat.com On 27.04.2011 23:12, Andi Kleen wrote: > On Wed, Apr 27, 2011 at 06:16:46PM +0200, Stefan Assmann wrote: >> BadRAM is a mechanism to exclude memory addresses (pages) from being used by >> the system. The addresses are given to the kernel via kernel command line. >> This is useful for systems with defective RAM modules, especially if the RAM >> modules cannot be replaced. >> >> command line parameter: badram=,[,...] >> >> Patterns for the command line parameter can be obtained by running Memtest86. >> In Memtest86 press "c" for configuration, select "Error Report Mode" and >> finally "BadRAM Patterns" >> >> This has already been done by Rick van Rein a long time ago but it never found >> it's way into the kernel. > > Looks good to me, except for the too verbose printks. Logging > every page this way will be very noisy for larger areas. You're right, logging every page marked would be too verbose. That's why I wrapped that logging into pr_debug. http://www.kernel.org/doc/local/pr_debug.txt This way it shouldn't bother anybody but it still could be useful in the case of debugging. However I kept the printk in the case of early allocated pages. The user should be notified of the attempt to mark a page that's already been allocated by the kernel itself. > > The mask will also only work for very simple memory interleaving > setups, so I suspect it won't work for a lot of modern systems > unless you go more fancy. > > Longer term there should be also likely a better way to specify > these pages than the kernel command line, e.g. the new persistent > store on some systems. I'd be happy to help improving and refining things for more fancy scenarios after this is done. Thanks for the feedback Andi. 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