Building an SDK on a machine with 8GB RAM resulted in excessive swapping
due to the xz compressor using ~20GB of memory. This is because xz is
being called with "-T 0 -9".
To allow tuning the compression versus memory usage, introduce a variable
named SDK_XZ_OPTIONS that defaults to a more sane default:
SDK_XZ_OPTIONS ?= "${XZ_DEFAULTS} ${SDK_XZ_COMPRESSION_LEVEL}"
The use of XZ_DEFAULTS fixes the excessive memory usage.
The SDK_XZ_COMPRESSION_LEVEL variable allows overriding the speed vs
compression. In an office or development environment the extra time
spent on compressing a few percent more is just not worth it.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
