Re: [RFC PATCH] u-boot: remove UBOOT_MACHINE and COMPATIBLE_MACHINES

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Tue, 2011-05-17 at 16:37 -0700, Darren Hart wrote:
> 
> On 05/17/2011 04:15 PM, Richard Purdie wrote:
> > On Tue, 2011-05-17 at 16:00 -0700, Darren Hart wrote:
> >> oe-core does not define any machines, so it does not make sense to
> >> add machine specific information in the oe-core u-boot recipe and
> >> infrastructure.
> >>
> >> Since every machine wishing to use the u-boot recipe would need to add itself to
> >> COMPATIBLE_MACHINES, typically via a bbappend recipe, the mechanism loses any
> >> utility it may have had and unecessarily complicates using the u-boot recipe. By
> >> removing it, we simplify the task of adding support for new machines.
> > 
> > NAK.
> > 
> > This break usability of things like "bitbake world" since all of a
> > sudden it will try and build u-boot in cases where it makes no sense
> > (qemu* machines for example).
> 
> OK, I thought there might be something like that surrounding
> COMPATIBLE_MACHINE, thus the RFC.
> 
> > 
> > I know it sounds strange but we do want this recipe enabled on a case by
> > case basis (and we have the beagleboard as a reference platform using it
> > which is handy). This means the default of no supported machine is
> > correct even if it looks odd.
> > 
> > Having the recipe deselect itself (raise a skip parsing event) if
> > UBOOT_MACHINE isn't set instead of using COMPATIBLE_MACHINE would be
> > acceptable though.
> 
> That sounds promising. I'd like to avoid having to create a
> u-boot_git.bbappend everytime you want to use u-boot. Is there an
> example you can think of that does this? greping for "deselect" and
> "skip pars" didn't yield any results.

grepping base.bbclass for COMPATIBLE_MACHINE might be more productive :)

The key piece is:

need_machine = bb.data.getVar('COMPATIBLE_MACHINE', d, 1)
if need_machine:
    import re
        this_machine = bb.data.getVar('MACHINE', d, 1)
        if this_machine and not re.match(need_machine, this_machine):
                raise bb.parse.SkipPackage("incompatible with machine %s" % this_machine)

which I think shows what I'm talking about clearly. And yes, ideally
this would have been called SkipRecipe but its from the days when we
were much more confused about terminology ;-).

Cheers,

Richard