Re: [bitbake-devel] Trouble capturing layer revision as variable in recipe

["Richard Purdie" <richard.purdie@linuxfoundation.org>]

On Wed, 2021-08-18 at 19:21 +0000, Chris Laplante via lists.openembedded.org wrote:
> Hello all,
>  
> We are on Yocto ‘zeus’.
>  
> Our u-boot recipe generates a versions.txt file containing the git commit of 
> the U-Boot source tree. It was pointed out that since recipes can patch the 
> source, just the source commit ID isn’t quite enough. So we wanted to also 
> include the git commit of the layer housing the recipe. Call this layer 
> “meta-our-layer”.
>  
> This is the implementation we tried:
>  
> def get_layer_path(d, name):
>     layer_list = (d.getVar("BBLAYERS") or "").split()
>     return [os.path.abspath(l) for l in layer_list if l.endswith(name)][0]
>  
> def get_meta_our_layer_commit(d):
>     import subprocess
>     output = subprocess.check_output(["git", "rev-parse", "HEAD"], universal_newlines=True,
> cwd=d.getVar("OUR_LAYER_PATH"))
>     return output.strip()
>  
> OUR_LAYER_PATH := "${@get_layer_path(d, "meta-our-layer")}"
>  
> OUR_LAYER_COMMIT = "${@get_meta_our_layer_commit(d)}"
> OUR_LAYER_COMMIT[vardepvalue] = "${@get_meta_our_layer_commit(d)}"
>  
> do_deploy_append() {
>     echo “meta-our-layer:${OUR_LAYER_COMMIT}” >> ${DEPLOYDIR}/versions.txt
> }
>  
>  
> However there are two problems:
>    1. Making an empty commit to meta-our-layer doesn’t cause the recipe to be 
> re-run. What’s weird is that when I use ‘bitbake u-boot –e’, I can see that 
> the value of  OUR_LAYER_COMMIT is indeed changing. And with bitbake-dumpsig
>  I can see that OUR_LAYER_COMMIT is in the task deps for do_deploy.
>    2. If I build ‘u-boot’, then make an empty commit to meta-our-layer, and 
> then run “bitbake-whatchanged u-boot”, I get a “The metadata is not deterministic
>  and this needs to be fixed.” error.
>  
> Am I misunderstanding the purpose of vardepvalue? I thought it could be used to 
> here to help bitbake ‘see’ through values that otherwise change unexpectedly.

I suspect you need to have bitbake always reparse the recipe too. Maybe
BB_DONT_CACHE = "1" ?

Cheers,

Richard