From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-f69.google.com (mail-lf0-f69.google.com [209.85.215.69]) by kanga.kvack.org (Postfix) with ESMTP id 2BD116B007E for ; Thu, 28 Apr 2016 12:42:34 -0400 (EDT) Received: by mail-lf0-f69.google.com with SMTP id 68so69134304lfq.2 for ; Thu, 28 Apr 2016 09:42:34 -0700 (PDT) Received: from mail.rt-rk.com (mx2.rt-rk.com. [89.216.37.149]) by mx.google.com with ESMTPS id z21si38258519wmh.56.2016.04.28.09.42.32 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 28 Apr 2016 09:42:32 -0700 (PDT) Received: from localhost (localhost [127.0.0.1]) by mail.rt-rk.com (Postfix) with ESMTP id 7F2461A2399 for ; Thu, 28 Apr 2016 18:42:30 +0200 (CEST) Received: from [10.80.11.84] (rtrkn220.domain.local [10.80.11.84]) by mail.rt-rk.com (Postfix) with ESMTPSA id 6C2271A221F for ; Thu, 28 Apr 2016 18:42:30 +0200 (CEST) From: Bojan Prtvar Subject: memtest help Message-ID: <57223D77.6020502@rt-rk.com> Date: Thu, 28 Apr 2016 18:42:31 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: linux-mm@kvack.org Hello everyone, I need to test all RAM cells on a linux ARM embedded system. My use case is very similar to the one described in [1] expect the fact I also have strong requirements on minimizing the boot time impact. Instead of doing that from the bootloader, I decided to evaluate the linux memtest feature introduced with [2]. My questions are: 1) Does the early_memtest() as called in [3] really covers *all* RAM cells? 2) As memtest happens very early in boot stage, what primitives I can use to measure duration of early_memtest()? Are there any known heuristics? I need to test ~2GB of RAM. This is my major concern. 3) It seems reasonable to expose the number of detected bad cells to user space. I was thinking about sysfs. Are the patches welcomed? [1] http://www.linuxforums.org/forum/newbie/173847-how-do-memory-ram-test-when-linux-running.html [2] http://lkml.iu.edu/hypermail/linux/kernel/1503.1/00566.html [3] http://lxr.free-electrons.com/source/arch/arm/mm/init.c#L291 Thanks, Bojan -- 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/ . Don't email: email@kvack.org