When download kernel source directly without using setupworkspace.sh script, the sources$JETPACK_VERSION directory is absent for apply_patches_ext.sh, and instead should be ./Linux_for_tegra/source/public, which is supplied via the source_dir parameter ($1)
Added default value for $SRCS, which is not set in build_all.sh if source dir parameter is missing
Signed-off-by: Junze Wu junze.wu@intel.com