From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [216.145.245.199] (helo=mx03.dls.net) by linuxtogo.org with esmtp (Exim 4.69) (envelope-from ) id 1LvFmU-0006wp-Ey for openembedded-devel@openembedded.org; Sat, 18 Apr 2009 21:00:50 +0200 Received: from [209.242.7.134] (helo=[192.168.231.111]) by mx03.dls.net with esmtpa (Exim 4.69) (envelope-from ) id 1LvFiT-0000AP-Nh for openembedded-devel@openembedded.org; Sat, 18 Apr 2009 13:56:41 -0500 Message-ID: <49EA225D.2040304@dls.net> Date: Sat, 18 Apr 2009 13:56:29 -0500 From: "Mike (mwester)" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.21) Gecko/20090302 Thunderbird/2.0.0.21 Mnenhy/0.7.6.0 MIME-Version: 1.0 To: openembedded-devel@openembedded.org References: <20090414234609.GA27890@denix.org> <1239752998-7677-1-git-send-email-denis@denix.org> <20090416163353.GG17629@smtp.west.cox.net> <20090418175649.GZ17629@smtp.west.cox.net> In-Reply-To: <20090418175649.GZ17629@smtp.west.cox.net> Subject: Re: [PATCH] udev 124: add cache invalidation logic on kernel change or its bootargs/cmdline X-BeenThere: openembedded-devel@lists.openembedded.org X-Mailman-Version: 2.1.11 Precedence: list Reply-To: openembedded-devel@lists.openembedded.org List-Id: Using the OpenEmbedded metadata to build Distributions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 18 Apr 2009 19:00:50 -0000 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Tom Rini wrote: > On Sat, Apr 18, 2009 at 11:31:38AM +0200, Koen Kooi wrote: >> On 16-04-09 18:33, Tom Rini wrote: >>> On Tue, Apr 14, 2009 at 07:49:58PM -0400, Denys Dmytriyenko wrote: >>> >>>> Signed-off-by: Denys Dmytriyenko >>>> --- >>>> recipes/udev/udev-124/init | 10 +++++++++- >>>> 1 files changed, 9 insertions(+), 1 deletions(-) >>> So, for making it optional, how about adding something to /etc/default >>> to enable / disable dev caching all together? And, I believe >>> /proc/atags would just be cp /proc/atags /tmp/atags || touch /tmp/atags. >> Do we really want atags in there? As the name says, they are ARM TAGs, >> and only when kexec is enabled. Does it buy us anything over >> /proc/cmdline? > > I'll leave that up to mwester as it was his suggestion originally. Executive Summary: I don't really care one way or another. Detail for why this was mentioned in the first place: The discussion that led up the ARM ATAG suggestion involved an exploration of all the possible things that could happen to a device that might cause trouble because of a stale cache. Using /proc/cmdline is good, but the suggestion to use the ATAG list was offered because it captures not just the command line itself, but might also capture other hardware changes. As a specific example, consider the use case where one takes a bootable SD-card image from one om-gta02 device, and plugs it into a different one with a different hardware version (significant on the om-gta0x devices). The use of /proc/cmdline will result in a stale cache; the use of /proc/atags will catch that the revision number in the atag list has changed. Is that sufficient reason to use /proc/atags? I think that's a pretty far-fetched and unusual use-case, and if someone is doing that, they should expect things to break. So I have no real-world concern if just /proc/cmdline is used. Regards, Mike (mwester)