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[RFC,02/16] kvm tools: only enable LTO if supported by GCC

Message ID 1352721450-11340-3-git-send-email-will.deacon@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Will Deacon Nov. 12, 2012, 11:57 a.m. UTC 
Commit 99423f12db2a ("kvm tools: enable LTO") unconditionally enabled
link-time-optimisations when building kvmtool. Unfortunately, passing
-flto to a GCC without support for the option, results in a fatal build
error:

  cc1: error: LTO support has not been enabled in this configuration

This patch adds a check to the kvm tools Makefile so that LTO is only
enabled if the host compiler supports it.

Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 tools/kvm/Makefile |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)
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Patch

diff --git a/tools/kvm/Makefile b/tools/kvm/Makefile
index f12e587..23a7c40 100644
--- a/tools/kvm/Makefile
+++ b/tools/kvm/Makefile
@@ -226,6 +226,11 @@  ifeq ($(call try-cc,$(SOURCE_AIO),$(FLAGS_AIO) -static),y)
 	LIBS_STATOPT	+= -laio
 endif
 
+FLAGS_LTO := -flto
+ifeq ($(call try-cc,$(SOURCE_HELLO),$(FLAGS_LTO)),y)
+	CFLAGS		+= $(FLAGS_LTO)
+endif
+
 ifneq ($(call try-build,$(SOURCE_STATIC),-static,),y)
 $(error No static libc found. Please install glibc-static package.)
 endif
@@ -244,7 +249,7 @@  DEFINES	+= -DKVMTOOLS_VERSION='"$(KVMTOOLS_VERSION)"'
 DEFINES	+= -DBUILD_ARCH='"$(ARCH)"'
 
 KVM_INCLUDE := include
-CFLAGS	+= $(CPPFLAGS) $(DEFINES) -I$(KVM_INCLUDE) -I$(ARCH_INCLUDE) -I$(KINCL_PATH)/include/uapi -I$(KINCL_PATH)/include -I$(KINCL_PATH)/arch/$(ARCH)/include/uapi -I$(KINCL_PATH)/arch/$(ARCH)/include/ -O2 -fno-strict-aliasing -g -flto
+CFLAGS	+= $(CPPFLAGS) $(DEFINES) -I$(KVM_INCLUDE) -I$(ARCH_INCLUDE) -I$(KINCL_PATH)/include/uapi -I$(KINCL_PATH)/include -I$(KINCL_PATH)/arch/$(ARCH)/include/uapi -I$(KINCL_PATH)/arch/$(ARCH)/include/ -O2 -fno-strict-aliasing -g
 
 WARNINGS += -Wall
 WARNINGS += -Wcast-align