Use -isystem for linux-headers dir

glibc and Linux-provided headers are known to generate macro
redefinition warnings when used together.  For example:
<linux/mman.h> and <sys/mman.h> duplicate some macro definitions.

We normally never see those warnings because GCC suppresses
warnings generated by system headers.  We carry our own copy of
Linux header files, though, and this makes those warnings not be
suppressed when glibc headers are included before Linux headers
(e.g. if <sys/mman.h> is included before <linux/mman.h>).

Use -isystem instead of -I for linux-headers.  This makes the
compiler treat our linux-headers directory the same way it treats
system-provided Linux headers, and suppress warnings generated by
them.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/Makefile.target b/Makefile.target
index 2d43dc586a108aca248a03e56a5ae0b8706abd4e..934a9f7431dc6fb6ef83a9d5587907b24eb33cca 100644 (file)
--- a/Makefile.target
+++ b/Makefile.target
@@ -12,7 +12,7 @@ endif
 
 $(call set-vpath, $(SRC_PATH):$(BUILD_DIR))
 ifdef CONFIG_LINUX
-QEMU_CFLAGS += -I../linux-headers
+QEMU_CFLAGS += -isystem ../linux-headers
 endif
 QEMU_CFLAGS += -iquote .. -iquote $(SRC_PATH)/target/$(TARGET_BASE_ARCH) -DNEED_CPU_H
 

diff --git a/configure b/configure
index 44a70cfa8c4e234988e2e6a238aeaf393e07c707..06fcd070fb3758ed681f616fc816d2621c52238e 100755 (executable)
--- a/configure
+++ b/configure
@@ -900,7 +900,7 @@ Linux)
   linux="yes"
   linux_user="yes"
   kvm="yes"
-  QEMU_INCLUDES="-I\$(SRC_PATH)/linux-headers -I$PWD/linux-headers $QEMU_INCLUDES"
+  QEMU_INCLUDES="-isystem \$(SRC_PATH)/linux-headers -isystem $PWD/linux-headers $QEMU_INCLUDES"
   supported_os="yes"
   libudev="yes"
 ;;