[oe] get OE git hash tag in executable

[Paul Eggleton]

On Saturday 28 January 2012 13:42:32 Frans Meulenbroeks wrote:
> In order to allow backtracking of the sources for a binary build with OE, I
> would like to (automatically) add the hash of the top level commit (and
> maybe also the branch) of the oe git tree my recipe lives in).
> E.g. in main.c I would like to have a var say:
> const char * const buildfrom = "oe branch 2011.03-maintence hash
> 1234567890"; or something like that.
> 
> What would be the best way to get that info into my program?
> (my best guess at the moment is to use a macro and compile with
> -DOE_IDENT="....." or so and say  char *buildfrom = OE_IDENT; but not
> really sure what the best way is to fill OE_IDENT and pass it to the
> recipe.)

Interesting question! Putting the information in a define specified on the 
compiler command line would be one way; another way would be to have the 
recipe write to/append to/subsitute into a header file that you can #include in 
the source. You would also probably want to include ${DATE} in the recipe's PV 
or use some other mechanism to ensure it gets rebuilt every time you build an 
image.

I guess you are still using OE-Classic, but in OE-Core we now have a function 
in base.bbclass called get_layers_branch_rev that will return the git 
branch/revision information for all enabled layers. It was split out from the 
code in the same bbclass that displays this information when BitBake starts, 
so I guess you could just make a copy of it into your recipe for OE-Classic.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre