Re: [pull-oe-uboot 1/2] u-boot: remove UBOOT_MACHINE and COMPATIBLE_MACHINES

[Darren Hart <dvhart@linux.intel.com>]

On 05/26/2011 09:18 AM, Phil Blundell wrote:
> On Thu, 2011-05-26 at 15:37 +0100, Richard Purdie wrote:
>> u-boot in OE-Core would need something like COMPATIBLE_MACHINE = ""
>> which makes this harder.
> 
> Yes, true.  I don't think that's a major problem, though, you just need
> a regex that won't match anything.  Something like:
> 
> COMPATIBLE_MACHINE = "(?!^)"
> 
> would probably do what you want, though it does have the admitted
> downside of looking rather like line noise.  
> 
> If this is going to be a common problem then it might be worth hacking
> base.bbclass about a bit to provide a more convenient way to do it.  The
> UBOOT_MACHINE thing is fine as a solution for u-boot since that variable
> needs to exist anyway, but I wouldn't have been keen on introducing it
> just to control the recipe acceptability.
> 
>> Its usually seem to work out easier to just do:
>>
>> COMPATIBLE_MACHINE_mymachine = "mymachine"
>>
>> which avoids several potential issues.
> 
> Yeah, that would work fine too: you could even save a bit of typing by
> just using "" as the rvalue since an empty C_M will (somewhat
> counterintuitively) permit everything.

Really?... <looks into base.bbclass and data_smart.py> Huh, you are
correct. I wouldn't have expected that.

>  I got the impression from
> Darren's original phraseology of "resorting to machine-specific
> overrides" that he didn't like it much, though.

Right, it just starts to look rather ugly in the recipe, especially for
BSPs supporting more than just a couple of machines. I also think that
having to use machine overrides is an indicator that the mechanism is
not working for the purpose it was designed for.

-- 
Darren Hart
Intel Open Source Technology Center
Yocto Project - Linux Kernel