[yocto] Bitbake problems recognizing the latest version of a repo

[Paul Eggleton]

Hi Jakob,

On Thursday, 29 March 2018 12:41:33 AM NZST Jakob Hasse wrote:
> Right now it's still a mystery for me when bitbake builds the latest 
> version of a repository and why. I make changes in my code and whether I 
> commit them or not, sometimes bitbake builds a package with the recent 
> version, sometimes with an old version.
> So my strategy is doing mock changes (adding whitespaces, "enhencing" 
> documentation) and adding signed commits as well as forcing a PR in the 
> recipe and re-running bitbake until it works somehow (I heard the 
> bitbake prefers the signed commits somehow could not verify this yet).
> 
> Hence, I would like to know what I have to do to build only the latest 
> version of a repository...
> 1. When it's local on my computer (with EXTERNALSRC_BUILD_pn-<package> = 
> "/home/some/local/location/" in local.conf),

If you are using the externalsrc class (specifically with EXTERNALSRC set, 
since EXTERNALSRC_BUILD only controls where the build is actually run) then 
you should find that any change to files within the source tree should trigger 
do_compile to rerun next time you build the recipe. If that does not happen 
then that's a bug which we should explore further.

> 2. When I build from a github or any remote repository.

In this case you need to be pulling the latest revision:

SRCREV = "${AUTOREV}"

If you need to specify a branch other than master, use ;branch=branchname in 
SRC_URI.

In order to force it to rebuild the latest version every time however, you 
will likely also need something like this:

PV = "1.0+git${SRCPV}"

The "1.0" bit can be anything you like - usually it would be whatever the 
latest release version was prior to the commit. A couple of further notes: 

1) The result of the above will be that every time you run a build, even if 
the recipe in question is not being built, bitbake will need to query the 
remote repository in order to determine the latest available version.

2) If you want to ensure that PV never appears to go backwards (which is 
important if you are using package management to perform upgrades within the 
target image) then you will need to enable the PR server - see the manual for 
information on how to do this.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre