[OE-core] [PATCH 0/2] Extensible SDK improvements

[Adrian Freihofer]

On Sat, 2020-03-07 at 12:40 +0000, Richard Purdie wrote:
> On Sat, 2020-03-07 at 12:54 +0100, Adrian Freihofer wrote:
> > Hi Richard,
> > 
> > We have found two already supported ways to copy variables from the
> > bitbake environment local.conf to the eSDK local.conf
> > 
> > If a variable is defined in the local.conf bitbake environment,
> > SDK_LOCAL_CONF_WHITELIST and SDK_LOCAL_CONF_BLACKLIST can be used to
> > add it to the local.conf eSDK file.
> > 
> > If a variable should be statically defined for the eSDK but not for
> > the
> > bitbake environment, sdk-extra.conf is useful.
> > 
> > Now we would like to add a third way to add variables which are
> > dynamically calculated by bitbake but need to be statically added to
> > the eSDK local.conf. For example we would like to support something
> > like that:
> > 
> > def get_version_from_git(d):
> >     version = d.getVar("GIT_VERSION", True)
> >     if version:
> >         return version                    # runs in eSDK
> >     else:
> >         return bb.process.run("git...     # runs in bitbake
> > 
> > GIT_VERSION := "${@get_version_from_git(d)}"
> > 
> > SDK_LOCAL_CONF_EXTRALIST_append = " GIT_VERSION"
> 
> This worries me a bit since it means the eSDK and the "real" build can
> behave differently. I appreciate that can happen even with the other
> variables and means of setting them but this takes it to a new level.
> 
That I understand. The usage of the SDK_LOCAL_CONF_EXTRALIST would be
very specific. Wrong usage would lead to a broken sstate in the eSDK.

> Ultimately I think we're aiming to have normal builds convert into an
> eSDK and vice versa more easily. This seems to pull us further away
> from that :/.
> 
> What is the reasoning for having them behaving differently?

Our goal is to equate the eSDK behavior with the behavior of the real
build, also for the example with the GIT_VERSION, which bitbake and git
will dynamically evaluate at eSDK build time.

Suppose we want to compile the GIT_VERSION (last tag) from poky without
any manual steps into the firmware. bitbake can simply call

$ describe git --tags --dirty
uninative-2,8-74-g56446f4570-dirty

With Bitbake the variable can change. But in eSDK the GIT_VERSION must
be a constant. The above function behaves like a constant if
GIT_VERSION is defined in the local.conf for example. But it has a
dynamic behavior if GIT_VERSION is undefined. The only missing part in
the current Poky, is a way to automatically write the value to the
local.conf of the eSDK. I don't think this would be much different than
the already existing sdk-extra.conf file.

Regards,
Adrian

> Cheers,
> 
> Richard
> 
> 
>