[OE-core] Submission of 'emit-buildvars' class?

[Enrico Scholz]

Alexander Kanavin <alex.kanavin at gmail.com> writes:

>> we are using for some time an 'emit-buildvars' class which exports
>> bitbake variables into makefile fragments.  This class is used for for
>> developing of kernel, u-boot and other low level software and for
>> generic packaging.
>
> I don't quite understand how this is useful? Can you provide specific
> usage scenarios please?

I ma doing perhaps 70% of my development for kernel, u-boot and barebox.
Building them with the actual toolchain requires only a

| make -f ../Makefile.kernel tftp

Result is available after a few seconds on the TFTP server; when using a
specialized variant ('kbuild-file=...'), even faster so that it can be
used in Emacs flymake mode.


Ditto for other programs (testsuites or so); you write your recipe with
all the 'DEPENDS', execute the 'emit_buildvars' task and build your
application with

| make -f ../Makefile.common R=my-app

When you see that something is missing in DEPENDS, add it, reexecute
'emit_buildvars' and it will be in the per-package sysroot.  Excluding
the build time of the dependency, this won't take more than 30 seconds.


Or, it is trivial to run unfsd in the enviornment of the image recipe
and to build kernel modules with

| make -f ../Makefile.kernel modules modules-install

These modules will be installed there and can be used immediately on the
target system:

| # rmmod foo-module
| # modprobe foo-module


I do not know, how this can be done with plain OE.  As said, SDKs are too
heavy weighted, 'devshell' too slow and can not be scripted, 'externalsrc'
is broken, slow and can not be scripted.


Enrico