From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A4D54C433FE for ; Wed, 16 Feb 2022 19:57:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238394AbiBPT51 (ORCPT ); Wed, 16 Feb 2022 14:57:27 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:41798 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233169AbiBPT5Z (ORCPT ); Wed, 16 Feb 2022 14:57:25 -0500 Received: from elvis.franken.de (elvis.franken.de [193.175.24.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id B7335222DE6; Wed, 16 Feb 2022 11:57:12 -0800 (PST) Received: from uucp (helo=alpha) by elvis.franken.de with local-bsmtp (Exim 3.36 #1) id 1nKQQI-00055x-01; Wed, 16 Feb 2022 20:57:10 +0100 Received: by alpha.franken.de (Postfix, from userid 1000) id 84055C250A; Wed, 16 Feb 2022 20:54:23 +0100 (CET) Date: Wed, 16 Feb 2022 20:54:23 +0100 From: Thomas Bogendoerfer To: Chuanhong Guo Cc: linux-mips@vger.kernel.org, Rui Salvaterra , Ilya Lipnitskiy , linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] MIPS: ralink: mt7621: do memory detection on KSEG1 Message-ID: <20220216195423.GA17551@alpha.franken.de> References: <20220211001345.3429572-1-gch981213@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220211001345.3429572-1-gch981213@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 11, 2022 at 08:13:44AM +0800, Chuanhong Guo wrote: > It's reported that current memory detection code occasionally detects > larger memory under some bootloaders. > Current memory detection code tests whether address space wraps around > on KSEG0, which is unreliable because it's cached. > > Rewrite memory size detection to perform the same test on KSEG1 instead. > While at it, this patch also does the following two things: > 1. use a fixed pattern instead of a random function pointer as the magic > value. > 2. add an additional memory write and a second comparison as part of the > test to prevent possible smaller memory detection result due to > leftover values in memory. > > Fixes: 139c949f7f0a MIPS: ("ralink: mt7621: add memory detection support") > Reported-by: Rui Salvaterra > Signed-off-by: Chuanhong Guo > --- > arch/mips/ralink/mt7621.c | 36 +++++++++++++++++++++++------------- > 1 file changed, 23 insertions(+), 13 deletions(-) applied to mips-fixes. Thomas. -- Crap can work. Given enough thrust pigs will fly, but it's not necessarily a good idea. [ RFC1925, 2.3 ]