We have pre-compiled host tools tar which contains the tools from staging_dir/host/bin.
In order to reduce/optimize the compile time of build host tools, need to use scripts/ext-tools.sh.
The script takes the --host_build_dir and --host-staging-dir-stamp as input arguments (by default, build_dir/host and staging_dir/host/stamp respectively), along with the --tools argument to use the prebuilt host tools tar and update timestamps.
For the first time build, to use this script we wouldn't have build_dir/host and staging_dir/host/stamp.
We could able to see the host tools are being compiled even after using this script.
Also analysed, tools/Makefile, and could see stampfile being called to compile tool
$(curdir)//compile = $(STAGING_DIR)/.prepared $(STAGING_DIR_HOST)/.prepared
# prerequisites for the individual targets
$(curdir)/ := .config prereq
$(curdir)/install: $(curdir)/compile
tools_enabled = $(foreach tool,$(sort $(tools-y) $(tools-)),$(if $(filter $(tool),$(tools-y)),y,n))
$(eval $(call stampfile,$(curdir),tools,compile,,_$(subst $(space),,$(tools_enabled)),$(STAGING_DIR_HOST)))
$(eval $(call stampfile,$(curdir),tools,check,$(TMP_DIR)/.build,,$(STAGING_DIR_HOST)))
$(eval $(call subdir,$(curdir)))
Do precompiled tools work if fixing the timestamp? or do we need to modify Makefile to use the pre-compiled host tools similar to external toolchain?