bitbake.conf: more deterministic xz compression (threads)
xz archives can be non-deterministic / non-reproducible:
a) archives are created differently in single- vs
multi-threaded modes
b) xz will scale down the compression level so as to
be try to work within any memory limit given to
it when operating in single-threaded mode
This means that due to bitbake's default of using as many
threads as there are cores in the system, files compressed
with xz will be different if built on a multi-core system
compared to single-core systems. They will also potentially
be different if built on single-core systems with different
amounts of physical memory, due to bitbake's default of
limiting xz's memory consumption.
Force multi-threaded operation by default, even on single-core
systems, so as to ensure archives are created in the same
way in all cases.
Signed-off-by: André Draszik <git@andred.net> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
