This makes the disk usage footprint of building the kernel smaller in 3
ways:
1) There is no separate kernel source derivation
2) Rather than using the entire build tree, only the output of make
modules_prepare is kept in the $dev output (plus the module symbol
versioning file generated during the build)
3) Only the subset of the source tree known to be needed for external
builds is kept in $dev
Note that while 2) is supported by official kernel documentation, I
couldn't find any source describing what we need to keep for 3). I've
started with the bare minimum (the main Makefile is called by the
Makefile generated by make modules_prepare) and we can/should add more
as needed for kernelPackages.
Signed-off-by: Shea Levy <shea@shealevy.com>
2c38df1c5b