[PATCH v2 1/6] perf: build: Setup PKG_CONFIG_LIBDIR for cross compilation

[Leo Yan]

On recent Linux distros like Ubuntu Noble and Debian Bookworm, the
'pkg-config-aarch64-linux-gnu' package is missing. As a result, the
aarch64-linux-gnu-pkg-config command is not available, which causes
build failures.

When a build passes the environment variables PKG_CONFIG_LIBDIR or
PKG_CONFIG_PATH, like a user uses make command or a build system
(like Yocto, Buildroot, etc) prepares the variables and passes to the
Perf's Makefile, the commit keeps these variables for package
configuration. Otherwise, this commit sets the PKG_CONFIG_LIBDIR
variable to use the Multiarch libs for the cross compilation.

Signed-off-by: Leo Yan <leo.yan@xxxxxxx>
---
 tools/build/feature/Makefile | 26 +++++++++++++++++++++++++-
 tools/perf/Makefile.perf     | 26 +++++++++++++++++++++++++-
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index ed54cef450f5..084f803093c3 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -82,7 +82,31 @@ FILES=                                          \
 
 FILES := $(addprefix $(OUTPUT),$(FILES))
 
-PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
+# Some distros provide the command $(CROSS_COMPILE)pkg-config for
+# searching packges installed with Multiarch. Use it for cross
+# compilation if it is existed.
+ifneq (, $(shell which $(CROSS_COMPILE)pkg-config))
+  PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
+else
+  PKG_CONFIG ?= pkg-config
+
+  # PKG_CONFIG_PATH or PKG_CONFIG_LIBDIR is required for the cross
+  # compilation. If both is not set, try to set the lib paths installed
+  # by multiarch.
+  ifdef CROSS_COMPILE
+    ifeq ($(PKG_CONFIG_LIBDIR)$(PKG_CONFIG_PATH),)
+      CROSS_ARCH = $(shell $(CC) -dumpmachine)
+      PKG_CONFIG_LIBDIR := /usr/local/$(CROSS_ARCH)/lib/pkgconfig/
+      PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/local/share/pkgconfig/
+      PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/local/lib/$(CROSS_ARCH)/pkgconfig/
+      PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/lib/$(CROSS_ARCH)/pkgconfig/
+      PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/share/pkgconfig/
+      export PKG_CONFIG_LIBDIR
+      $(warning Missing PKG_CONFIG_LIBDIR and PKG_CONFIG_PATH for cross compilation,)
+      $(warning set PKG_CONFIG_LIBDIR=$(PKG_CONFIG_LIBDIR) for building with Multiarch libs.)
+    endif
+  endif
+endif
 
 all: $(FILES)
 
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 5c35c0d89306..2c9e89415e48 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -193,7 +193,31 @@ HOSTLD  ?= ld
 HOSTAR  ?= ar
 CLANG   ?= clang
 
-PKG_CONFIG = $(CROSS_COMPILE)pkg-config
+# Some distros provide the command $(CROSS_COMPILE)pkg-config for
+# searching packges installed with Multiarch. Use it for cross
+# compilation if it is existed.
+ifneq (, $(shell which $(CROSS_COMPILE)pkg-config))
+  PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config
+else
+  PKG_CONFIG ?= pkg-config
+
+  # PKG_CONFIG_PATH or PKG_CONFIG_LIBDIR is required for the cross
+  # compilation. If both is not set, try to set the lib paths installed
+  # by multiarch.
+  ifdef CROSS_COMPILE
+    ifeq ($(PKG_CONFIG_LIBDIR)$(PKG_CONFIG_PATH),)
+      CROSS_ARCH = $(shell $(CC) -dumpmachine)
+      PKG_CONFIG_LIBDIR := /usr/local/$(CROSS_ARCH)/lib/pkgconfig/
+      PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/local/share/pkgconfig/
+      PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/local/lib/$(CROSS_ARCH)/pkgconfig/
+      PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/lib/$(CROSS_ARCH)/pkgconfig/
+      PKG_CONFIG_LIBDIR := $(PKG_CONFIG_LIBDIR):/usr/share/pkgconfig/
+      export PKG_CONFIG_LIBDIR
+      $(warning Missing PKG_CONFIG_LIBDIR and PKG_CONFIG_PATH for cross compilation,)
+      $(warning set PKG_CONFIG_LIBDIR to $(PKG_CONFIG_LIBDIR) for using libs with Multiarch.)
+    endif
+  endif
+endif
 
 RM      = rm -f
 LN      = ln -f
-- 
2.34.1