Re: [PATCH] qemu.inc: Use '=' for IMAGE_FSTYPES

[Tom Rini <tom.rini@gmail.com>]

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 <trini@ti.com>
> > ---
> >  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...

-- 
Tom