From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id 478F46B0253 for ; Fri, 29 Apr 2016 05:22:19 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id e190so216761386pfe.3 for ; Fri, 29 Apr 2016 02:22:19 -0700 (PDT) Received: from foss.arm.com (foss.arm.com. [217.140.101.70]) by mx.google.com with ESMTP id ul1si21444299pab.19.2016.04.29.02.22.18 for ; Fri, 29 Apr 2016 02:22:18 -0700 (PDT) Subject: Re: memtest help References: <57223D77.6020502@rt-rk.com> From: Vladimir Murzin Message-ID: <572327BE.7030606@arm.com> Date: Fri, 29 Apr 2016 10:22:06 +0100 MIME-Version: 1.0 In-Reply-To: <57223D77.6020502@rt-rk.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Bojan Prtvar , linux-mm@kvack.org On 28/04/16 17:42, Bojan Prtvar wrote: > 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? No. > > 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. Stopwatch? > > 3) > It seems reasonable to expose the number of detected bad cells to user > space. I was thinking about sysfs. Are the patches welcomed? > $ dmesg | grep "bad mem" Cheers Vladimir > [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 > > -- 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