[PATCH 2/5] kbuild: print short log in addition to the whole command with V=1

[Masahiro Yamada <masahiroy@kernel.org>]

"make V=1" prints the whole command instead of the short log, but I
think it is nicer to print both so that you can easily spot the build
rule of your interest.

This commit changes V=1 to print the short log (the line starts with
'#'), followed by the full log.

In parallel builds, the short/full logs from the same build rule may
be interspersed. To avoid it, please add -Otarget along with the -j<N>
option. Kbuild will never set -Otarget by default because Make would
buffer the logs and lose the escape sequences. (Modern compilers print
warnings and errors in color, but only when they write to a terminal.)

This is also a preparation for supporting V=12 because V=2 appends the
reason for rebuilding to the short log.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 Makefile               | 18 +++++++-----------
 scripts/Kbuild.include | 26 +++++++++++++-------------
 2 files changed, 20 insertions(+), 24 deletions(-)

diff --git a/Makefile b/Makefile
index e8ce3e2b30d6..ce98dfd8359a 100644
--- a/Makefile
+++ b/Makefile
@@ -56,22 +56,18 @@ unexport GREP_OPTIONS
 # Beautify output
 # ---------------------------------------------------------------------------
 #
-# Normally, we echo the whole command before executing it. By making
-# that echo $($(quiet)$(cmd)), we now have the possibility to set
-# $(quiet) to choose other forms of output instead, e.g.
+# Most of build commands in Kbuild start with "cmd_". You can optionally define
+# "quiet_cmd_*". If defined, the short log is printed. Otherwise, no log from
+# that command is printed by default.
 #
-#         quiet_cmd_cc_o_c = Compiling $(RELDIR)/$@
-#         cmd_cc_o_c       = $(CC) $(c_flags) -c -o $@ $<
-#
-# If $(quiet) is empty, the whole command will be printed.
-# If it is set to "quiet_", only the short version will be printed.
-# If it is set to "silent_", nothing will be printed at all, since
-# the variable $(silent_cmd_cc_o_c) doesn't exist.
+# e.g.)
+#    quiet_cmd_depmod = DEPMOD  $(MODLIB)
+#          cmd_depmod = $(srctree)/scripts/depmod.sh $(DEPMOD) $(KERNELRELEASE)
 #
 # A simple variant is to prefix commands with $(Q) - that's useful
 # for commands that shall be hidden in non-verbose mode.
 #
-#	$(Q)ln $@ :<
+#    $(Q)$(MAKE) $(build)=scripts/basic
 #
 # If KBUILD_VERBOSE equals 0 then the above command will be hidden.
 # If KBUILD_VERBOSE equals 1 then the above command is displayed.
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 2f7356b2990b..faae3c7986b0 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -125,15 +125,15 @@ dtbinst := -f $(srctree)/scripts/Makefile.dtbinst obj
 # $(Q)$(MAKE) $(clean)=dir
 clean := -f $(srctree)/scripts/Makefile.clean obj
 
-# echo command.
-# Short version is used, if $(quiet) equals `quiet_', otherwise full one.
-echo-cmd = $(if $($(quiet)cmd_$(1)),\
-	echo '  $(call escsq,$($(quiet)cmd_$(1)))$(echo-why)';)
-
-# sink stdout for 'make -s'
-       redirect :=
- quiet_redirect :=
-silent_redirect := exec >/dev/null;
+# pring log
+#
+# If quiet is "silent_", print nothing and sink stdout
+# If quiet is "quiet_", print short log
+# If quiet is empty, print short log and whole command
+silent_log_print = exec >/dev/null;
+ quiet_log_print = $(if $(quiet_cmd_$1), echo '  $(call escsq,$(quiet_cmd_$1)$(why))';)
+       log_print = echo '$(pound) $(call escsq,$(or $(quiet_cmd_$1),cmd_$1 $@))'; \
+                   echo '  $(call escsq,$(cmd_$1))';
 
 # Delete the target on interruption
 #
@@ -156,8 +156,8 @@ delete-on-interrupt = \
 		$(foreach sig, HUP INT QUIT TERM PIPE, \
 			trap 'rm -f $@; trap - $(sig); kill -s $(sig) $$$$' $(sig);))
 
-# printing commands
-cmd = @set -e; $(echo-cmd) $($(quiet)redirect) $(delete-on-interrupt) $(cmd_$(1))
+# print and execute commands
+cmd = @$(if $(cmd_$(1)),set -e; $($(quiet)log_print) $(delete-on-interrupt) $(cmd_$(1)),:)
 
 ###
 # if_changed      - execute command if any prerequisite is newer than
@@ -234,7 +234,7 @@ if_changed_rule = $(if $(if-changed-cond),$(rule_$(1)),@:)
 # (6) No dir/.target.cmd file and target not listed in $(targets)
 #     This is a good hint that there is a bug in the kbuild file
 ifeq ($(KBUILD_VERBOSE),2)
-why =                                                                        \
+_why =                                                                        \
     $(if $(filter $@, $(PHONY)),- due to target is PHONY,                    \
         $(if $(wildcard $@),                                                 \
             $(if $(newer-prereqs),- due to: $(newer-prereqs),                \
@@ -251,7 +251,7 @@ why =                                                                        \
          )                                                                   \
      )
 
-echo-why = $(call escsq, $(strip $(why)))
+why = $(space)$(strip $(_why))
 endif
 
 ###############################################################################
-- 
2.34.1