[poky] Customizing kernels

[Tom Rini]

On 07/27/2011 01:08 PM, Gary Thomas wrote:
> On 2011-07-27 13:58, Tom Rini wrote:
>> On 07/27/2011 10:25 AM, Gary Thomas wrote:
>>> To run a customized kernel configuration, I've been doing this:
>>>    % bitbake virtual/kernel
>>>    % bitbake virtual/kernel -c menuconfig
>>>    % bitbake virtual/kernel -c compile -f
>>>    % bitbake virtual/kernel
>>>
>>> Is there some way that the kernel recipes (probably kernel.bbclass)
>>> could mark the compile state as invalid so that the '-c compile -f'
>>> step is no longer needed (implied)?
>>
>> What's the reason around the first bitbake?  I know with pstage you
>> needed to do that for an empty TMPDIR to populate out everything else,
>> but sstate shouldn't have that weakness.  It should just be:
>> $ bitbake virtual/kernel -c menuconfig
>> $ bitbake virtual/kernel
> 
>>
>> And get populating from sstate correct.
>>
> 
> The first step was just to get started, e.g. from scratch (no sstate, etc)

In that case, you can just to -c menuconfig and then build, but...

> The situation I'm really talking about is when you've already built the
> whole thing (presumably a full image, etc) and then want to change some
> kernel option, e.g. add a non-module driver and not rebuild the kernel
> from scratch, just recompile the required bits.  In this case, if you
> just run the two steps you quote, nothing happens during the second
> step because bitbake thinks that the whole recipe is complete.  Once
> you run '-c compile -f', it will rerun the compile and that invalidates
> the steps that follow in the recipe so they all run as well.

Yes, this is annoying.  The problem stems from menuconfig being
optional.  You could do instead:
bitbake -f -c configure virtual/kernel
bitbake -c menuconfig virtual/kernel
bitbake virtual/kernel

But indeed, that's not much better, it's just re-ordering things.  I
don't know off hand if there's a way to mark a task as invalid from
another task, which is what's needed here (especially when we move the
menuconfig bits to where busybox/etc can use them).

-- 
Tom Rini
Mentor Graphics Corporation