From: Masahiro Yamada masahiroy@kernel.org
[ Upstream commit 174a1dcc96429efce4ef7eb2f5c4506480da2182 ]
When building with 'make -s', no output to stdout should be printed.
As Arnd Bergmann reported [1], mkimage shows the detailed information of the generated images.
I think this should be suppressed by the 'cmd' macro instead of by individual scripts.
Insert 'exec >/dev/null;' in order to redirect stdout to /dev/null for silent builds.
[Note about this implementation]
'exec >/dev/null;' may look somewhat tricky, but this has a reason.
Appending '>/dev/null' at the end of command line is a common way for redirection, so I first tried this:
cmd = @set -e; $(echo-cmd) $(cmd_$(1)) >/dev/null
... but it would not work if $(cmd_$(1)) itself contains a redirection.
For example, cmd_wrap in scripts/Makefile.asm-generic redirects the output from the 'echo' command into the target file.
It would be expanded into:
echo "#include <asm-generic/$*.h>" > $@ >/dev/null
Then, the target file gets empty because the string will go to /dev/null instead of $@.
Next, I tried this:
cmd = @set -e; $(echo-cmd) { $(cmd_$(1)); } >/dev/null
The form above would be expanded into:
{ echo "#include <asm-generic/$*.h>" > $@; } >/dev/null
This works as expected. However, it would be a syntax error if $(cmd_$(1)) is empty.
When CONFIG_TRIM_UNUSED_KSYMS is disabled, $(call cmd,gen_ksymdeps) in scripts/Makefile.build would be expanded into:
set -e; { ; } >/dev/null
..., which causes an syntax error.
I also tried this:
cmd = @set -e; $(echo-cmd) ( $(cmd_$(1)) ) >/dev/null
... but this causes a syntax error for the same reason.
So, finally I adopted:
cmd = @set -e; $(echo-cmd) exec >/dev/null; $(cmd_$(1))
[1]: https://lore.kernel.org/lkml/20210514135752.2910387-1-arnd@kernel.org/
Signed-off-by: Masahiro Yamada masahiroy@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/Kbuild.include | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 509e0856d653..f0b6dbd3c7fe 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -170,8 +170,13 @@ clean := -f $(srctree)/scripts/Makefile.clean obj 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; + # printing commands -cmd = @set -e; $(echo-cmd) $(cmd_$(1)) +cmd = @set -e; $(echo-cmd) $($(quiet)redirect) $(cmd_$(1))
### # if_changed - execute command if any prerequisite is newer than