[bitbake-devel] [yocto] Ordering of anonymous Python functions and task signature calculations

[richard.purdie at linuxfoundation.org]

On Thu, 2018-07-26 at 09:22 -0500, Matt Hoosier wrote:
> On Wed, Jul 25, 2018 at 4:58 PM Richard Purdie
> <richard.purdie at linuxfoundation.org> wrote:
> Your advice about BB_DONT_CACHE does cause reparsing to get
> triggered. I can see that in logs.
>  
> > and that the
> > task dependency exists. You have the dependency above and that is
> > the
> > easier piece to fix.
> 
> But this part I'm not seeing. The variable's value is always
> recalculated (sometimes more than once during a Bitbake run, but
> that's okay because it's idempotent), but the task only re-executes
> if the payload of the .bb file itself has changed. The blurb I wrote
> above:
> 
>   do_install[vardepsalwaysdirty] = " EXTERNALLY_INFLUENCED_VARIABLE "
> 
> is just some nonsense syntax I wrote there to illustrate my point. I
> don't think there's any var flag called "vardepsalwaysdirty". Did you
> have this line in mind when you were saying that I'd already gotten
> the task made dependent on the variable? Or were you just noting that
> the syntactic use of the variable inside of the task should engage
> the normal hash-based task-dependency calculation logic?
>  
> > If the recipe is reparsed, the anon python reruns and the task hash
> > recalculated.
> 
> Is there anything extra I need to do to cause the reparsed variable's
> hash to cascade to the task?

I think I understand what you're asking now. The key thing is:

conf/bitbake.conf:AUTOREV[vardepvalue] = "${SRCPV}"
conf/bitbake.conf:SRCPV[vardepvalue] = "${SRCPV}"

which makes SRCREV/AUTOREV work.

For your specific example you'd want:

EXTERNALLY_INFLUENCED_VARIABLE[vardepvalue] = "${EXTERNALLY_INFLUENCED_VARIABLE}"

which will add the value of the variable to the task hash.

Cheers,

Richard