From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vms173021pub.verizon.net ([206.46.173.21]) by linuxtogo.org with esmtp (Exim 4.72) (envelope-from ) id 1SCFms-0005MC-Gw for openembedded-core@lists.openembedded.org; Mon, 26 Mar 2012 21:41:06 +0200 Received: from gandalf.denix.org ([unknown] [71.178.225.66]) by vms173021.mailsrvcs.net (Sun Java(tm) System Messaging Server 7u2-7.02 32bit (built Apr 16 2009)) with ESMTPA id <0M1I002SVBL2JQO0@vms173021.mailsrvcs.net> for openembedded-core@lists.openembedded.org; Mon, 26 Mar 2012 14:31:50 -0500 (CDT) Received: by gandalf.denix.org (Postfix, from userid 1000) id E18FA201CB; Mon, 26 Mar 2012 15:31:49 -0400 (EDT) Date: Mon, 26 Mar 2012 15:31:49 -0400 From: Denys Dmytriyenko To: Patches and discussions about the oe-core layer Message-id: <20120326193149.GA3368@denix.org> References: <1332524132-24689-1-git-send-email-trini@ti.com> <1332753313.28414.91.camel@ted> <20120326162531.GD21518@bill-the-cat> <1332780976.28414.130.camel@ted> <20120326171359.GE21518@bill-the-cat> MIME-version: 1.0 In-reply-to: <20120326171359.GE21518@bill-the-cat> User-Agent: Mutt/1.5.20 (2009-06-14) Subject: Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES X-BeenThere: openembedded-core@lists.openembedded.org X-Mailman-Version: 2.1.11 Precedence: list Reply-To: Patches and discussions about the oe-core layer List-Id: Patches and discussions about the oe-core layer List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 26 Mar 2012 19:41:06 -0000 Content-type: text/plain; charset=us-ascii Content-disposition: inline On Mon, Mar 26, 2012 at 10:13:59AM -0700, Tom Rini wrote: > On Mon, Mar 26, 2012 at 05:56:16PM +0100, Richard Purdie wrote: > > On Mon, 2012-03-26 at 09:25 -0700, Tom Rini wrote: > > > On Mon, Mar 26, 2012 at 10:15:13AM +0100, Richard Purdie wrote: > > > > On Fri, 2012-03-23 at 10:35 -0700, Tom Rini wrote: > > > > > As per > > > > > http://lists.linuxtogo.org/pipermail/openembedded-core/2012-March/019772.html > > > > > a machine conf file should use '=' to set IMAGE_FSTYPES. > > > > > > > > > > Signed-off-by: Tom Rini > > > > > --- > > > > > meta/conf/machine/include/qemu.inc | 2 +- > > > > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > > > > > As someone pointed out, what I mentioned in that email sadly doesn't > > > > work although it would be nice if they did. I suspect this is why we're > > > > using += since: > > > > > > We aren't using += today. We (openembedded-core) use ?=. meta-intel > > > uses += and meta-ti is mixed (and I don't have meta-fsl-* handy). > > > > > > > > - The machine needs to say 'I need or support the following formats' > > > > > > > > so the machine ensures those formats exist at a minimum: > > > > > > > > IMAGE_FSTYPES += "xxxx" > > > > > > > > > - The distro needs to say 'I always want format X' > > > > > > > > so the distro can do: > > > > > > > > IMAGE_FSTYPES += " yyy" > > > > > > > > > - The user needs to say 'I know best, give me only format X' > > > > > > > > This one is the problem case so the user has to use overrides: > > > > > > > > IMAGE_FSTYPES_override = "X" > > > > > > > > (where override can be MACHINE or forcevariable) > > > > > > > > > - The user needs to say 'I know best, give me what you support + X' > > > > > > > > IMAGE_FSTYPES += " X" > > > > > > > > > > > > Whilst I think that is less than ideal since it forces use of overrides > > > > in local.conf to override, changing the += in machine conf files doesn't > > > > gain us much, it just breaks += in local.conf. > > > > > > > > I'm open to other feedback though... > > > > > > Well, I suggested ??= / ?= and posted some results from bitbake -e... > > > > Ok. += plays out as above. I realise its not what is in qemu.inc, it is > > used in meta-intel though which I looked at after qemu.inc and I guess > > has confused me. > > > > With ?= in machine.conf: > > > > The user defined IMAGE_FSTYPES would override the machine ones. Distro > > can still append to it. The downside is a user append would not work out > > as expected. > > > > So the question is which is the more user expected behaviour? > > > > =+ makes overwriting IMAGE_FSTYPES hard > > > > ?= makes appending IMAGE_FSTYPES hard > > > > I suspect a user is more likely to want to append than overwrite. > > Getting an append to work with ?= is extremely non-obvious, even worse > > syntax than the =+ overwriting case with overrides. > > > > So bottom line, I'm tempted to recommend we use =+. > > I think for the upcoming release, =+ is good enough and we can talk > about adding further variables after if it's still too complicated. So, > now where's the repo that documenting these examples should go in? So, did we come full circle on this? :) Started here: https://lists.yoctoproject.org/pipermail/meta-ti/2012-March/000779.html I'm fine changing it for meta-ti, if we agree on a unified solution. Having an EXTRA/MACHINE var for that in the future might simplify things... -- Denys