Why pass PLATFORM and other parameters to slave.mk in Makefile.work?

[jeromesun14]

Description

It's a question. Code in Makefile.work:

SONIC_BUILD_INSTRUCTION :=  make \
                           -f slave.mk \
                           PLATFORM=$(PLATFORM) \
                           BUILD_NUMBER=$(BUILD_NUMBER) \
                           BUILD_TIMESTAMP=$(BUILD_TIMESTAMP) \
                           ENABLE_DHCP_GRAPH_SERVICE=$(ENABLE_DHCP_GRAPH_SERVICE) \
                           SHUTDOWN_BGP_ON_START=$(SHUTDOWN_BGP_ON_START) \
                           SONIC_ENABLE_PFCWD_ON_START=$(ENABLE_PFCWD_ON_START) \
                           SONIC_ENABLE_SYNCD_RPC=$(ENABLE_SYNCD_RPC) \
                           SONIC_INSTALL_DEBUG_TOOLS=$(INSTALL_DEBUG_TOOLS) \
                           PASSWORD=$(PASSWORD) \
                           USERNAME=$(USERNAME) \
                           SONIC_BUILD_JOBS=$(SONIC_BUILD_JOBS) \
                           KERNEL_PROCURE_METHOD=$(KERNEL_PROCURE_METHOD) \
                           HTTP_PROXY=$(http_proxy) \
                           HTTPS_PROXY=$(https_proxy) \
                           SONIC_ENABLE_SYSTEM_TELEMETRY=$(ENABLE_SYSTEM_TELEMETRY)

Question: Main Makefile or Makefile.work doesn't include rules/config, I think parameters like PASSWORD=$(PASSWORD) makes no sense here.

I think it takes effect because slave.mk include rules/config:

include $(RULES_PATH)/config
include $(RULES_PATH)/functions
include $(RULES_PATH)/*.mk
ifneq ($(CONFIGURED_PLATFORM), undefined)
include $(PLATFORM_PATH)/rules.mk
endif

ifeq ($(USERNAME),)
override USERNAME := $(DEFAULT_USERNAME)
else
$(warning USERNAME given on command line: could be visible to other users)
endif

ifeq ($(PASSWORD),)
override PASSWORD := $(DEFAULT_PASSWORD)
else
$(warning PASSWORD given on command line: could be visible to other users)
endif

ifeq ($(SONIC_DEBUGGING_ON),y)
DEB_BUILD_OPTIONS_GENERIC := "nostrip"
endif

ifeq ($(SONIC_PROFILING_ON),y)
DEB_BUILD_OPTIONS_GENERIC := "nostrip noopt"
endif

ifeq ($(SONIC_BUILD_JOBS),)
override SONIC_BUILD_JOBS := $(SONIC_CONFIG_BUILD_JOBS)
endif

ifeq ($(KERNEL_PROCURE_METHOD),)
override KERNEL_PROCURE_METHOD := $(DEFAULT_KERNEL_PROCURE_METHOD)
endif

MAKEFLAGS += -j $(SONIC_BUILD_JOBS)
export SONIC_CONFIG_MAKE_JOBS

[yxieca]

@sunnogo ,

These parameters were there and passed into slave.mk so that we could override the default config.

e.g. the default config could set PASSWORD='foo', and you can issue "make PASSWORD=bar" to set the password to 'bar' instead.

Please let me know if you have further questions.

Cheers,
Ying

[jeromesun14]

@yxieca Thanks! It's a dynamic way compare to static way in rules/config. I didn't compile by this way before, and I will have a try if I need to enable a new feature next time.