linux-yocto-custom: Clarify usage and clear COMPATIBLE_MACHINE
There has been some confusion over proper use of the linux-yocto-custom
recipe. It is not intended to build as is from meta-skeleton. It should
be modified via a bbappend file to provide a Linux kernel config at the
very least.
Update the commentary to make this requirement more explicit. Add some
additional detail about how to create a bbappend file and how and when
to modify the various variables.
Clear COMPATIBLE_MACHINE so bitbake will not attempt to build the recipe
unless the user explicitly adds there machine to the variable, which
should encourage them to read the recipe comments before attempting to
build it.
Signed-off-by: Darren Hart <dvhart@linux.intel.com> CC: Bruce Ashfield <bruce.ashfield@windriver.com> CC: Tom Zanussi <tom.zanussi@intel.com> Signed-off-by: Darren Hart <dvhart@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
