[yocto] Where does the bitbake get the variable "TOPDIR"

[Eren Türkay]

On Tue, Dec 18, 2012 at 08:28:32PM +0800, Biao wrote:
> >http://hambedded.org/blog/2012/11/24/from-bitbake-hello-world-to-an-image/
> I will try to give some feedback after finishing the reading.
> But for now, there are some silly questions:
> 1. There is a base_do_fetch() {}, I did not find the explanation of the keyword of 'base' in the manual, do i miss something?

I don't know the internals of bitbake on that level but as far as I
understand, bitbake uses the name of the bbclass file as a prefix in the
function names for the sake of abstraction. So, as in autotools.bbclass,
the tasks defined in base.bbclass gets prefixes with "base_" keyword.
Probably, it's related with mapping the function names when 'inherit'
keyword is used.

I'm not clear on this topic either. A hand from an experienced bitbake
guru would be really helpful here. The type of abstraction in bitbake
should be explained in detail as well as how EXPORT_FUNCTION works.

Any volunteers?

> 2. There is 'bb.note' and 'bbnote' in the code example, is it a type-mistake or something else?

No, this is not a mistake. You can use python as well as shell functions
in bitbake recipes and classes. See 'python' keyword in function
definitons where bb.note is used. That's why python function "bb.note()"
is used to print log information. Without python keyword, the bitbake
function is treated as shell.

Regards,
Eren

-- 
    . 73! DE TA1AET
      http://linkedin.com/in/erenturkay
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