From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw0-f47.google.com ([209.85.213.47]) by linuxtogo.org with esmtp (Exim 4.72) (envelope-from ) id 1SCDdH-0003GA-1e for openembedded-core@lists.openembedded.org; Mon, 26 Mar 2012 19:23:03 +0200 Received: by yhjj56 with SMTP id j56so3976641yhj.6 for ; Mon, 26 Mar 2012 10:14:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=date:from:to:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:organization :user-agent; bh=XZQ7oUt7cVNeNVsUTr+VgLirl73q/mGaamcKO4Tshwo=; b=a2jiZKpWmC66I310ipmH0EWuTTtyV1rJVdt8ZxSZZ/7Nguj2XJEbFvX2oGCwza/1Uc hrd6kmxV7nfPK/U89MuDDT7B+D+fjL1ENgDOv3JSv382A+Ef0fc1+2NJY/Z7FSdRjJia 9RBGUnTWhx1WjsA+bLYaoZ788epMXvDURYEImkWOQfv4pqJL9se4xrICMl8Eyrx+hx24 AMo2DplLPXUvkeEjyCr9gHeTohr0kt+/eK+2vtPVvh5M7hQCTbAxY9OpFLe6JjChVVV8 JADcBslXH+AvuNssMzUceaGQDHEN3lBAG2+Xb2k4mXvdXwyY0zI3YpYsyN/3pwF6vBh7 0qFw== Received: by 10.60.3.9 with SMTP id 9mr27679746oey.49.1332782042518; Mon, 26 Mar 2012 10:14:02 -0700 (PDT) Received: from bill-the-cat (ip68-230-54-74.ph.ph.cox.net. [68.230.54.74]) by mx.google.com with ESMTPS id v9sm16915235obo.9.2012.03.26.10.14.00 (version=TLSv1/SSLv3 cipher=OTHER); Mon, 26 Mar 2012 10:14:01 -0700 (PDT) Date: Mon, 26 Mar 2012 10:13:59 -0700 From: Tom Rini To: Patches and discussions about the oe-core layer Message-ID: <20120326171359.GE21518@bill-the-cat> 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> MIME-Version: 1.0 In-Reply-To: <1332780976.28414.130.camel@ted> Organization: Texas Instruments 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 17:23:03 -0000 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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? -- Tom