[oe] Building a kernel with builtin initramfs

[Paul Sokolovsky]

Hello,

Sometimes, it may be necessary to have a kernel with builtin initramfs.
Initramfs commonly kernel modules, so we have kernel build recursion.
Standard way to break this loop is to split procedure causing recursion
into independent steps, so we'd first build kernel modules, then build
initramfs, then build a kernel image.

The question, is how to express this with bitbake and OE. Skipping
various ideas, here's the one which promise viability:

1. Have a kernel-modules.bb, which will execute bitbake recursively to
build a PREFERRED_PROVIDER_virtual/kernel, and will pass a special flag
variable.

2. Detecting that flag, kernel.bbclass will build/package only modules.

3. Then, have a kernel-initramfs.bb (DEPENDS=kernel-modules) which will
take a variable defining which initramfs image to build, if any, and
execute bitbake recursively with IMAGE_FSTYPES=cpio.gz on that.

4. Make a task in kernel.bbclass depend on kernel-initramfs.bb (build
task of it).


Again, that appears to be something working, at least from 1st look.
However, it introduces new trick - recursive execution of bitbake,
what, as far as I know, never happened so far. Well, for "make" such
usage is commodity, and the fact that it is required 2 times in the
above scenario show that it is useful ;-).


Other ideas?


-- 
Best regards,
 Paul                          mailto:pmiscml at gmail.com