From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754783Ab1LDQeY (ORCPT ); Sun, 4 Dec 2011 11:34:24 -0500 Received: from mail-out.m-online.net ([212.18.0.9]:45108 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754592Ab1LDQeW (ORCPT ); Sun, 4 Dec 2011 11:34:22 -0500 X-Auth-Info: qxuuTXRibQEAwknkPTccy4dvkabIhf0LtsAIb/bGmzU= To: Wolfram Sang cc: Heiko Schocher , Vitaly Bordug , devicetree-discuss@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org From: Wolfgang Denk Subject: Re: [PATCH] drivers, char: add U-Boot bootcount driver MIME-Version: 1.0 Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 8bit In-reply-to: <20111204114741.GA5788@pengutronix.de> References: <1322991921-21096-1-git-send-email-hs@denx.de> <20111204114741.GA5788@pengutronix.de> Comments: In-reply-to Wolfram Sang message dated "Sun, 04 Dec 2011 12:47:41 +0100." Date: Sun, 04 Dec 2011 17:34:17 +0100 Message-Id: <20111204163417.1AD6625EA22@gemini.denx.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dear Wolfram, in message <20111204114741.GA5788@pengutronix.de> you wrote: > > > Description: OSDL CGL specifies that carrier grade Linux > > shall provide support for detecting a repeating reboot cycle > > due to recurring failures. This detection should happen in > > user space before system services are started. > > So, technically, a flag would be enough, not necessarily a counter? Although a > counter probably has more advantages... The real-life applications we have seen so far all required a counter. They all required to switch to a recovery mode or other alternative boot sequence after N failed boot attempts, with N > 1 in all cases. > > reg = <0x23060 0x20>; > > I assume that non-volatile memory would qualify as a boot-counter, so those > could be tied to I2C busses etc? reg would not fit then. Actually all kind of non-volatile storage can be used - it depends on specific hardware roperties. Some SoCs have registers that are guaranteed not to change theier value during a reset; on other systems we have storage or NVRAM in RTCs or similar, or we can use SRAM, or I2C or SPI attached EEPROM, or even storage on SDCard, USB or other storage devices. This binding covers the memory type only. Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de "There is nothing new under the sun, but there are lots of old things we don't know yet." - Ambrose Bierce