Re: [PATCH v2 1/6] perf build: Conditionally add feature check flags for libtrace{event,fs}

[Namhyung Kim <namhyung@kernel.org>]

Hello,

On Wed, Jul 03, 2024 at 02:35:54PM +0200, Guilherme Amadio wrote:
> Hello,
> 
> On Tue, Jul 02, 2024 at 04:33:27PM -0700, Namhyung Kim wrote:
> > Hello,
> > 
> > On Fri, Jun 28, 2024 at 10:34:27PM +0200, Guilherme Amadio wrote:
> > > This avoids reported warnings when the packages are not installed.
> > > 
> > > Fixes: 0f0e1f44569061e3dc590cd0b8cb74d8fd53706b
> > > Signed-off-by: Guilherme Amadio <amadio@gentoo.org>
> > 
> > Thanks for working on this.
> > 
> > > ---
> > >  tools/perf/Makefile.config | 28 +++++++++++++++-------------
> > >  1 file changed, 15 insertions(+), 13 deletions(-)
> > > 
> > > diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
> > > index 5271a4c1d2b3..5387babb8f04 100644
> > > --- a/tools/perf/Makefile.config
> > > +++ b/tools/perf/Makefile.config
> > > @@ -182,13 +182,21 @@ endif
> > >  FEATURE_CHECK_CFLAGS-libzstd := $(LIBZSTD_CFLAGS)
> > >  FEATURE_CHECK_LDFLAGS-libzstd := $(LIBZSTD_LDFLAGS)
> > >  
> > > -# for linking with debug library, run like:
> > > -# make DEBUG=1 PKG_CONFIG_PATH=/opt/libtraceevent/(lib|lib64)/pkgconfig
> > > -FEATURE_CHECK_CFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --cflags libtraceevent)
> > > -FEATURE_CHECK_LDFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --libs libtraceevent)
> > > -
> > > -FEATURE_CHECK_CFLAGS-libtracefs := $(shell $(PKG_CONFIG) --cflags libtracefs)
> > > -FEATURE_CHECK_LDFLAGS-libtracefs := $(shell $(PKG_CONFIG) --libs libtracefs)
> > > +ifneq ($(NO_LIBTRACEEVENT),1)
> > > +  ifeq ($(call get-executable,$(PKG_CONFIG)),)
> > > +  dummy := $(error Error: $(PKG_CONFIG) needed by libtraceevent is missing on this system, please install it)
> > 
> > I know you just copied the code, but IIRC we wanted to remove this dummy
> > assignment before.
> 
> Sure, I will change this. I think we can also remove the "dummy :=" part and
> just do $(error Error: ...), like it's done in other places.
> 
> > > +  endif
> > > +endif
> > > +ifeq ($(shell $(PKG_CONFIG) --exists libtraceevent 2>&1 1>/dev/null; echo $$?),0)
> > > +  # for linking with debug library, run like:
> > > +  # make DEBUG=1 PKG_CONFIG_PATH=/opt/libtraceevent/(lib|lib64)/pkgconfig
> > > +  FEATURE_CHECK_CFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --cflags libtraceevent)
> > > +  FEATURE_CHECK_LDFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --libs libtraceevent)
> > > +endif
> > > +ifeq ($(shell $(PKG_CONFIG) --exists libtracefs 2>&1 1>/dev/null; echo $$?),0)
> > > +  FEATURE_CHECK_CFLAGS-libtracefs := $(shell $(PKG_CONFIG) --cflags libtracefs)
> > > +  FEATURE_CHECK_LDFLAGS-libtracefs := $(shell $(PKG_CONFIG) --libs libtracefs)
> > 
> > I'm curious if we can redirect stderr to /dev/null to surpress the
> > output when pkg-config is not installed.  Then we don't need to check
> > the `ifeq`.
> 
> I was wondering that myself when I added the check, if you prefer to redirect
> stderr to /dev/null, I will do it that way then when I submit v3.

Due to the timing of the merge window, I'll apply this patch (1/6 only)
with the following modification.  Please take a look and update v3.

Thanks,
Namhyung

---
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 5387babb8f04..a4829b6532d8 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -184,19 +184,17 @@ FEATURE_CHECK_LDFLAGS-libzstd := $(LIBZSTD_LDFLAGS)
 
 ifneq ($(NO_LIBTRACEEVENT),1)
   ifeq ($(call get-executable,$(PKG_CONFIG)),)
-  dummy := $(error Error: $(PKG_CONFIG) needed by libtraceevent is missing on this system, please install it)
+    $(error Error: $(PKG_CONFIG) needed by libtraceevent is missing on this system, please install it)
   endif
 endif
-ifeq ($(shell $(PKG_CONFIG) --exists libtraceevent 2>&1 1>/dev/null; echo $$?),0)
-  # for linking with debug library, run like:
-  # make DEBUG=1 PKG_CONFIG_PATH=/opt/libtraceevent/(lib|lib64)/pkgconfig
-  FEATURE_CHECK_CFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --cflags libtraceevent)
-  FEATURE_CHECK_LDFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --libs libtraceevent)
-endif
-ifeq ($(shell $(PKG_CONFIG) --exists libtracefs 2>&1 1>/dev/null; echo $$?),0)
-  FEATURE_CHECK_CFLAGS-libtracefs := $(shell $(PKG_CONFIG) --cflags libtracefs)
-  FEATURE_CHECK_LDFLAGS-libtracefs := $(shell $(PKG_CONFIG) --libs libtracefs)
-endif
+
+# for linking with debug library, run like:
+# make DEBUG=1 PKG_CONFIG_PATH=/opt/libtraceevent/(lib|lib64)/pkgconfig
+FEATURE_CHECK_CFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --cflags libtraceevent 2>/dev/null)
+FEATURE_CHECK_LDFLAGS-libtraceevent := $(shell $(PKG_CONFIG) --libs libtraceevent 2>/dev/null)
+
+FEATURE_CHECK_CFLAGS-libtracefs := $(shell $(PKG_CONFIG) --cflags libtracefs 2>/dev/null)
+FEATURE_CHECK_LDFLAGS-libtracefs := $(shell $(PKG_CONFIG) --libs libtracefs 2>/dev/null)
 
 FEATURE_CHECK_CFLAGS-bpf = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(SRCARCH)/include/uapi -I$(srctree)/tools/include/uapi
 # include ARCH specific config